Cambo is showing an Actus modified to accept a digital back. As you can see from the attached photo, the front and rear base are enhanced (reinforced and height is added for clearance of the digital back).
Cambo is showing an Actus modified to accept a digital back. As you can see from the attached photo, the front and rear base are enhanced (reinforced and height is added for clearance of the digital back).
Crap. Okay I want back in now. Lol
That maybe the best movement tech cam yet
Okay this is the sleeper of Photokinia 2014
Photography is all about experimentation and without it you will never learn art.
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I guess they really had to consider the effect it would have on future tech camera sales (WRS). If you are just starting out, with out lenses, this is a perfect solution.
You get movements, shift and swing/tilt. You can still mount the Schneider and Rodenstock lenses, but in a much less expensive mount, i.e Copol 0. No more need to spend the extra dollars for the Cambo T/S mount.
Knobs all look much larger also.
Your lenses actually hold more value, since you can sell them to anyone (all they need to do is add the mount for their camera, and not remove a Cambo mount)
Digital issues such as crosstalk will be the same dependent on the back/tech lens selected. But the cost of entry is I am assuming much less.
So it should be easy to really see just how future proof the Otus lens really is - for those of us that need a push
What will be cool is when somebody puts an Otus with an 250, 260 , or 280 back and measures the resolution in the center of the frame.
That would be intersesting and then compare it to the Sigma, Canon, and Nikon lenses. Maybe even Schneider and Rodenstock.
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But only for the newer CMOS back with true live view? I guess you can use ground glass, but it will be quite clumsy changing the back in and out.
Last edited by yatlee; 16th September 2014 at 17:32.
It is really neat that folks are rethinking the monorail camera. Great platform, but it seemed to fall out of favor. I think the real key is reducing the size--the Linhof CS679 was a great idea, but large and heavy. This looks really neat.
If I were Guy, I don't know how I could resist.
I'm already asking to test it. Lol
What usually is the criticism of these type of cameras (it's quite similar to Linhof Techno) is that it's not rigid and precise enough, that you get parallelism issues. The other criticism is ground glass focusing, but with live view coming up there are alternatives.
For a "low" cost entry to MF tech digital make sure to look at the CFV-50c which just now gets live view directly in the back through a firmware upgrade. At $15k is much cheaper than the Leaf and Phase One backs.
Anyway back to the camera; indeed a rigid pancake camera design can be more precise, but you get expensive mounts and generally more limited movements. For practical image making with f/11 and smaller apertures there's also a limit to how precise you need the camera to be. If you shoot infinity-focused grand views at f/8 or less I'd choose a pancake camera, but if you shoot with f/11 there's no need to go overkill - a lightweight camera rich in movements will do fine and give you more compositional flexibility. Learn to love some diffraction blur, it smoothes out aliasing artifacts
This Cambo Actus with digital back is really interesting. The main question to me is -- what wide angle lenses are you going to use with your CFV-50c / Credo 50 / IQ250? From say 50mm and up - Schneider Digitar and Rodenstocks will be fine, but below crosstalk will really become an issue if you want to be able to use the movements.
Don't forget the IQ150
I feel the whole issue of crosstalk is being conveniently overlooked by dealers. It's a real issue and if you buy the Actus or the Univeralis, from Arca, movements IMO would be a real key. On the smaller Sony 36MP sensor, the effect of crosstalk, (loss of color saturation) is pretty significant by 12mm of shift.
Each person has to see it and it's effects to understand just how important a factor it is.
I guess if you choose to use the 35mm lenses, or other 645 lenses, that the Cambo can support, this issue won't be as big a deal since the lens will much further away from the sensor (as the lenses were designed for a mirror box).
Similar results (very good) that Gerald has been getting with the Canon TS-E lenses on the Hcam and the IQ250.
Edit, I am assuming only the Nikon PC-E will work, as they have a manual aperture ring, the Canon's need a Hcam type setup to stop down the aperture ring.
Yes Canon lenses need a smart mount with electronics, and if you have a digital back also a focal plane shutter unit, which counts for Nikon lenses too.
I'm guessing that there will be no focal plane shutter unit for this one either, so you need leaf shutter lenses, or go with the DSLR/135 mirrorless version.
why would you need the camera movements if you are using the canon TS lenses? just to add the other axes?
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That is a pretty insulting thing to say Paul. It goes past implication, and actually infers that dealers have been withholding information on "crosstalk" issues when we sell a lens for use with a movement-based/technical camera. You're saying we're not addressing this with our clients? Paul, we don't sell a technical lens without discussing the limitations with our clients.
I have emails from 3 years ago discussing this with you.
I feel like the phenomenon of "Crosstalk" is slightly overblown. Creating a catchy name to an existing issue. And it is an issue - but just because a lens interacting with a CCD or CMOS sensor experiences "crosstalk" doesn't mean that combination is useless. It's certainly less useful than most would like, because it limits the amount of shift you can employ. And it's more extensive with the latest CMOS sensors compared to the previous and current CCD sensors.
This is not new. It now has a catchy name. And it is something that Capture Integration discusses with every client who is purchasing tech camera/lenses. In detail.
As a company that takes a LOT of pride in our integrity, I'm offended by your statement Paul.
Offended or not, it's pretty obvious that there's been a huge disconnect between lens designers, sensor designers, digital back designers and dealers.
The SK28 is a mystery from a lens design perspective. Designed just a few years ago it only works with Kodak sensors, and even there it pushes it more to the limit. Clearly the lens designers did not even check how digital sensors work, or hoped for some new technology to arrive in the future sooner than it has.
Then there's been myths of what color cast is at all. I've heard things like because MF sensors are so incredibly sensitive they record the color of the coatings from the lenses. For a layman it may not sound too unlikely, the magenta color of the coatings kind of look like what you see on the LCC shot. I don't really know from where the myth comes originally but I can imagine an ill-informed dealer tried to answer a customer question.
Such myths would never appear if there's been connection between lens designers, sensor designers, back manufacturers and dealers. But instead it seems like everyone has half-hearted tried to figure it out on their own with limited success.
Crosstalk is not just a catchy name, it's the correct technical term of what is happening, and the problem is has become worse for each new sensor generation, and is now peaking with the Sony CMOS sensors. Crosstalk differs from regular color cast (which is afaik caused by pixel vignetting variations due to unevenness of the pixels) in that it cannot be restored with the normal LCC process, therefore it's very important.
Before 2014 I have not ever seen a dealer mention crosstalk a single time. Then the IQ250 was released and tech cam tests showed real odd LCC failures, so I started reading technical papers on sensor design and found out the crosstalk metric and then all fell in place, these strange LCC failures were of course crosstalk. Learning more about the particular sensor designs and looking at microscope images of the sensors it became obvious this was a large problem. I even designed a crosstalk cancellation algorithm that could reverse crosstalk in some cases, but unfortunately not in as huge amounts as we see on the CMOS sensors.
It's also obvious to me that Phase One have never informed the dealers about what crosstalk is and why it cannot be corrected with LCC, and which problems that lead to. You have to excuse me but I don't believe that dealers "have known all along", nothing in all I've read and heard indicate that, and if they did know they have not been honest in the information to the customers. That people know about crosstalk now is through the information campaign I've had on this forum and LuLa.
These systems are not $500 cameras, it's $50k systems. I think customers can expect that designers, manufacturers and dealers are fully aware of technical limitations of this kind. This has not been the case, things have just been slapped together and hoping for the best. Then I think the least you can expect is to get criticism.
For similar reasons like the SK28 this Cambo Actus is partially a design mystery. It's clearly designed for CMOS sensors, but there are no good wide angle solutions available. Sure you could use it for 50mm and up, and not shift the wides. But the attraction of such a small compact camera is of course to use it outdoors and shoot landscape and architecture, and what is that without wide angle lenses? My assumption is that just like lens designers at Schneider Kreuznach that made the Digitar 28, the designers at Cambo designed this camera without fully understanding the crosstalk issue.
Last edited by torger; 17th September 2014 at 11:41.
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If crosstalk is overblown or not is a matter of taste. If I'd claim that you must have zero percent crosstalk for the lens/sensor combination to work alright then I'd exaggerate, unless I was talking about reproduction photography. 10% crosstalk usually have no visible effect on a picture. But with these CMOS sensors it's not these kind of levels were talking about, it can be 50+% even with normal amounts of shift, and vary depending on orientation of the sensor and other effects that may not seem logical.
Thus rather than do 1 or 2 casual tests without really knowing what's happening, what should be done is to contact lens designers and sensor designers, get the proper data and figure out how large image circle is when you can guarantee say no more than 10% crosstalk regardless of sensor orientation, so you can get guaranteed image performance. This is what I think a pro customer buying gear at this level could demand.
If find it a bit offending that dealers market the exactness of color and fine tonality of these backs, but think that crosstalk that severely degrades this performance metric shouldn't be taken more seriously than it is.
It seems like dealers hope for that the customer won't notice the degradation in color reproduction, and many perhaps will not -- you can be a great photographer while not having great color vision. If you buy a system at this level marketed for having supreme color and tonality then I think you should be allowed to expect that dealers take that seriously, even for wide angle lenses.
To be very clear -- if I had been designer at Cambo I would not release the Cambo Actus at this point, and if I hade been an MF dealer I would not market the product. Without proper wide angle support, which I don't see that it has, I think the use of it is too limited concerning that it is designed as a portable camera otherwise particularly suitable for wide angle shooting. I as a MF dealer would understand that customers interested in this camera would very likely want to shoot wide angle landscape and architecture with this, and then I would have to disappoint them, and therefore I'd say "this product is not market ready, we need new CMOS technology or new lenses before it's ready".
I don't mind that Cambo designers and MF dealers think otherwise, but I find it problematic that when criticism and questions concerning wide angle support and this "catchy" name crosstalk comes up over and over again causes irritation. You should have seen that coming with this design.
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Sorry you feel that way.
I can go back and find the emails you refer to, however I am also very sure that the term crosstalk, etc. was ever used. It was told to me then that the issue was the IC and optical quality of the lens that caused the problems. So that if you pushed a 70mm image circle lens much past 5mm on the Rodenstock 28 or if you pushed the Schneider 35mm XL much past 8mm on a 60mp sensor, you start to see a lot of color/saturation loss.
If you told then, that is was due to the angle of incidence due to the light striking the micro lens on the Dalsa sensor and then getting split, I don't remember those conversations.
From testing with 36MP 35mm sensors from Sony, I can clearly see that is is a huge issue for color if the photographer is interested in movements, which I am. The effect is not as harsh on CCD technology but very punishing on CMOS.
If you believe that the dealer community has come out with white papers and discussions explaining what the phenomenon is, so be it. I have not read any so I may have over stated my position. Obviously that should be something that can be provided.
I have asked repeatedly for more information on the issue and to be honest, Torger has been the best resource on the web. He has spent a lot of time making a clear definition of the problem, the cause and what could be done to fix it.
You obviously see it differently and for that we can agree to disagree.
I BELIEVE IF YOU CHECK OUT MY POST HISTORY ON THIS FORUM AND LULA, I always found praise for both CI and DT, and have posted as such. I have always listed your company and DT as a reference for people that are looking for more detailed information. I also don't feel I ever made a negative post in regards to CI. I also did not list any companies in my previous post.
If you want to call me out, fine. I don't see any reason to, but that's your call 100%
Let's be specific though - your response is to our affront at Paul's comment.
And what you say about dealers with regard to that - respectfully - is bulls**t.
Crosstalk might indeed be a technical term for the phenomenon, but you didn't discover it. Capture Integration was discussing lens limitations well before you labeled them as crosstalk. Weird stuff can happen between these lenses and the sensors used with them even when you're not shifting. Want to technically call this particular phenomonon crosstalk? I don't care. We describe the limitation of the lens with a given sensor. Anyone buying these systems needs to know what performance they will get and what limitations there are. That is discussed with every client we interface with.
It's also bulls**t that there has been public silence from dealers. On these and other forums, there has been public content from Capture Integration regarding usability factors with lens and sensor combinations. I think its great you're bringing attention to it - but you often write in absolutes, and while manufacturers are creating solutions that may encounter the issue, the arrows you're slinging at dealers is off the mark.
Manufacturers rarely fully inform dealers of any negatives with their product. I'm sorry, is this something new? I don't think so. That's why dealers have to find out for themselves. No - these are not $500 systems, they're $50,000 systems, and we take that completely to heart. You think we're going to rely on what a manufacturer tells us? What kind of dealers are you working with? Any dealer who sells, but doesn't test Rodenstock and Schneider lenses with movements on sensors for performance and limitations is not a dealer, they're an order taker.
Oh wait, you got me started and I'm not finished yet; what about the P65+ to IQ180 upgrades when people suddenly realized that wait, we really need to use Rodenstock lenses on this to make it work, and even then you get issues? I recently adviced an IQ180 + Rodenstock 32-HR owner to crossgrade to an IQ260, which he did and voila the ripple issues disappeared and he's very happy with the system performance again. I wonder what dealer that recommended him to buy the IQ180 + Rodie 32 combination in the first place, but these things happen.
Why haven't dealers been better at informing users before buying, before upgrading what will happen with lens compatibility in their lens lineup? I contacted a dealer for my interest in CFV-50 a while ago. He recommended that I would choose the new IQ250 instead. He knew I was a tech shooter. The CFV-50 happens to have the most crosstalk-resistent sensor, you can even use it to the edge with the otherwise near-hopeless SK28 (which I by the way had to figure out myself with the help of a forum user), while the IQ250 have the worst.
I think it's pretty much a scandal that dealers don't have better knowledge in this issue, they sell the stuff and suggest upgrades without knowing about compatibility issues.
Capture Integration may be a wonderful exception, so then I understand that you may see discussions about this like offensive, but I'm pretty sure that CI is one of the best informed dealers. Those upgrades and sales did happen, users got disappointed, or in the best case was happy to buy even more gear they didn't plan to do at first. In any case I don't think it's a healthy honest way to sell gear at this level. It's just sloppy.
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I would suggest that it is a good thing that Paul discusses his view. He sees some issues and tells about it. Same goes with Anders Torger. Well, except that Anders has done some deep work in raw conversion and also develops algorithms for suppressing crosstalk.
Another factor is that we may be more sensitive to some factors, personally I don't like aliasing, but you would see little of that shooting at f/16 or even f/11 on some backs. Shooting f/8 on my P45+, it is an issue. My experience, it is worth sharing.
My point is really that "your mileage may vary".
Not sure where to enter here but to be fair CMOS is very new to digital backs and honestly folks I have not been following MF stuff too much lately. But also lets be careful on the finger pointing too and that goes both ways of course. Im not going to sit here and try and work this out but I know everyone involved here and there is a lot of integrity floating between all parties. I will say this since I have been directly involved on some of this reports from OEMs to dealers has been absent on many occasions on any potential issue and it usually comes from dealers and users when these issues do come up. Not sure we can blame anyone sometimes on this stuff. If we remember the 180 on first blush it was dealers that found lens incompatibility, I know I helped with those tests. Anyway not sure where you guys want me to go here but lets do keep it respectful. I known CI for years and DT as well and sure they may miss something but I never known any intentional things. The crosstalk issue is new and I have not heard much about it until maybe a week ago. But again I have not been involved , next week I test the Credo 50 and maybe I will see something relevant or not.
Paul, you call it as you see it, I wouldn't want it any other way. If you have positive things to say about us - and they're true - that's wonderful. In this case - you called us out, and did so in a way that questions our integrity. If our integrity is questioned, I'll respond, that's a little different than "calling you out".
I never stated we had published "white papers". We've certainly shared our fair amount of tests, including files you yourself have viewed. The fact we didn't label it as "crosstalk" seems not as important to me as making sure you understood the limitation, no?
There are potentially more issues than just crosstalk when it comes to sensor/lens combinations. I've seen weird issues that have nothing to do with shifts. As a dealer, our responsibility is to make sure our client knows what to expect with the performance of their product. And that we do, as evidenced by your own admission.
There have been some attempts from manufacturers to publish (see attached), and the term crosstalk is even used. Could they do more to warn? Sure. But I'll come back to it - an order taker is not a dealer.
I agree - let's get off making it about Capture Integration - since we're such a wonderful exception. It just started with us being called out - and I got offended. Let's move on.
I can see the problem if a dealer doesn't sell technical camera equipment. You're right. Any dealer that does sell technical cameras should know about this, regardless of the manufacturer. Even when manufacturers do inform of negatives, they rarely fully inform. So, it really is incumbent upon the dealer to know this. These are $20,000 - $50,000 systems, after all, as you say. How can you sell a system that is designed to work with these technical cameras and not know there's limitations?
There's limitations everywhere - how can you at least not question the results? Manufacturers can inform better - but even if they do - any dealer needs to be able to know for themselves - and if they don't, how can they really legitimately sell this equipment? On our shelf we have practically every cam,era and lens that you could practically mount a digital back on, all the technical cameras and lenses, Contax systems, Hasselblad V systems, Mamiya RZ, 645 systems, etc, etc. Sinar view cameras - etc.
You're right Torger - manufacturers should be cognizant especially of a dealer who doesn't sell any tech camera equipment, though I wonder then why that dealer would not be selling that equipment anyway?
I just needed to get some stuff off my heart so I heated up a bit. Don't worry. I do stand by my views (ie that there's a disconnect in various designs as if designers were unaware of crosstalk issues, and crosstalk is a term dealers should be aware of and use more than they do), but I don't want to start a war. I've said my things and readers can decide for themselves what they think.
Concerning that Cast Effects document (haven't seen it before) it's very interesting and crosstalk is indeed mentioned and explained correctly and in an easy-to-understand way, followed by "Leaf camera back sensors have barriers and do not suffer from crosstalk", the first part may be correct (that barriers exist, not sure if they are there on newer Dalsa's though, in any case much less effective than Kodak's light shields), but the second part that they do not suffer from crosstalk is incorrect, it depends on lens and how much it's shifted. The document is from 2007 though, I don't really remember which backs and lenses that were in the marketplace then, it could have been correct at that time.
The doc also gives more details to normal color cast that I did not know yet, thanks for posting. (I think varying pixel vignetting is still a factor though, not mentioned in this document.)
The document you attached ends with this copyright note:
"© Kodak 2007. Leaf is a trademark of Kodak. All rights reserved. Data subject to change without notice. The Kodak products mentioned in this document are trademarks or service marks of Kodak and may be registered in certain jurisdictions. Other company and brand, product and service names are for identification purposes only and may be trademarks or registered trademarks of their respective holders."
Is it still valid for 2014 Sony Exmor based backs? On page 5 it says: "Leaf camera back sensors have barriers and do not suffer from crosstalk." Is this still valid for Sony Exmor based backs? Anders Torger has checked some SEM images from a Chipworks article on Exmor sensors and his conclusion was that no barrier was visible in the SEM images.
You are 100 percent correct. Original post was on a iPhone and if you read the first statement it's in bad English. It easily could have been taken the way you read it. It was not my intent. For that I apologize. I did not proof it however even before the edit, there are more the 2 Phase One dealers.
I hold to my original statement that on a public forum such as this I see no reason to raise a name unless in praise which I have done many times with CI.
I am only marginally intressed in this, as I am shooting a P45+ on a Hasselblad V and I would say both these are not really critical. The new Sony sensor is exciting, as it offers live view like on DSLRs, at least to my understanding, but the existing backs are a bit to expensive for me and I am not really interested in 1.3X crop factor sensors.
On the other side, live view should be very attractive on technical cameras, especially with tilts. So limitations should be discussed openly as I feel.
I would also add that I always feel that info coming from Steve is among the most reliable we can have.
I appreciate your comments on this. It is also good to know that Kodak sensors have some benefits over later generation Dalsa sensors and present generation Sony sensors.
I don't know if "Kodak" sensors are still made, by TrueSense, or if they are history.
US Representative, Arca-Swiss International
R-Line Technical Cameras, Large Format View Cameras, Ballheads D4, D4m, P1, P0, Z1, Z2, C1 Cube.
Erik: TrueSense (now owned by ON Semiconductor) still have the 50 megapixel kodak for sale, and it's used in the H5D-50, but that's the only current product that has it. All other has Dalsa or Sony sensors. The Kodaks are not state-of-the-art concerning noise performance, but have light shields (barriers) with better crosstalk suppression than the others. Barriers are probably not so easy to manufacture without causing loss in photodiode coverage, which means that it's better to not have them if you don't need them. AFAIK Sony's MF sensor don't have barriers at all, but you still have wiring of course (in horizontal or vertical direction) which work as a barrier to some extent, this wiring is what makes sensor have differen amount of crosstalk depending on orientation.
While Kodak has papers on their light shield design, I haven't really found any data on Dalsa tech. To me it seems that it's the wiring that stops crosstalk, but there are no dedicated barriers. Even on my old 33 megapixel Dalsa I can see visible crosstalk on SK35 and even SK60 at extreme shifts, in horizontal direction, vertical it's much less crosstalk. As Leaf has had Dalsa sensors all the time I guess that the paper was not really correct even in 2007. Few would consider the relatively low crosstalk on the 33 megapixel sensors a problem though in practical photography.
Guy: when you test Credo 50 you won't see any issues except for technical wide angles in shifted positions, or longer lenses with large IC and shifted very far (like the SK60XL). The old IQ250 thread with the library is good documentation of how the artifacts are manifested. What you see is desaturated color, in worse cases color shift and mazing in the demosaicing. As results vary depending on horizontal/vertical orientation and subject color it's not so easily predicted. It may subjectively work out in some scenes while not in others. That's why I think crosstalk should not be taken lightly. If you make one test you may be satisfied with the result due to that particular subject matter was not so sensitive to crosstalk, but over time you discover that you get poor results now and then.
The reason people disagree about this being an issue or not is that it's a large subjective component. How much can you compromise with color reproduction, it's subjective. I'm of the opinion that if you sell a system you should yourself have an established view on acceptable quality, and if a system does not live up to your standard you don't sell it, even if a customer may have lower standards than you have. Personally I think the Sony backs (and A7r) are past the limit of what's acceptable (too limited and unpredictable performance) and therefore one should not suggest using these with tech lenses wider than say 50-60mm, and in this context the Cambo Actus is an illogical product, but apparently many dealers have a different opinion. As long as customers are well-informed I guess it's okay.
Tech camera users are screaming for live view so I understand now when we have live view backs we want to use them on tech cameras. But I think we're in the space of wishful thinking. Live view is wanted so badly we stretch farther than we should concerning compromising our quality standards. The Cambo Actus is a very sexy product, but the technology is not ready. New sensors (back-illuminated or similar technology) or stronger retrofocus lenses are required to get a compatible package with good performance over the whole range. Stronger retrofocus would be a step in the wrong direction for tech cam land, so I hope better sensor technology comes first.
(As a sidenote, I don't like it when people say "lens limitations" because it's nothing wrong with the lenses -- use a film back and see, there's nothing wrong, no cast no nothing -- the whole term "lens color cast" puts focus on the lenses when it's actually "sensor limitations". What tech camera customers should want from the manufacturers is better sensors rather than "better" lenses. It's unfortunately easier to make lenses that compensate for sensor limitations than make sensors without these limitations though. Oh well, it's probably not too hard to make Kodak-style light shields but those that manufacture sensors optimize for other applications than tech wide optics.)
Last edited by torger; 18th September 2014 at 00:16.
Andres - I sincerely appreciate your input on this topic - as many do. As I agreed, you are correct, there is not enough widespread information being shared on the topic, and you've helped tremendously for many to better understand the issue.
I also understand your feelings about being technically correct in describing conditions. If we, as a dealer, use the phrase "this lens is limited" we mean it only in the most direct usefulness to the client. In the majority of cases, an existing sensor is already present, and lenses are being considered. In that case, most are sticking with their sensor, and so the focus is on the performance of a given lens with an already existing sensor. We understand that the sensor design is the core culprit, although your comment about film backs working perfectly fine still points to some culpability on the part of lens manufacturers, who are aware that their lenses are being used for digital capture, some of these lenses in a substantial majority of instances. Regardless - as a result of this, we typically describe the performance of individual lenses with one specific sensor to our clients because they usually have one sensor (and have already). They will have multiple lenses, and the lenses will react differently.
From the "solving the problem" perspective at the design end of things, it may be more important to you or manufacturers to think in terms of who or what is responsible. From the usage standpoint of these existing tools, at least in terms of recommending products, at the dealer level we feel it is more important to focus on the performance of the variable components, rather than the cause of the issue from one component that is already in their possession. There's nothing wrong with focusing on that, but our focus is more on what happens with that combination. We find that serves the person who is considering that lens best. It's slightly semantic, but we feel it helps our clients understand what lenses to choose for best results, depending on which sensor they have. "Which digital back are you shooting with" is typically the first question asked when someone asks for information on lenses to be used with tech cameras.
In terms of the subjectivity of color reproduction, or even quality in general, you're absolutely right - it is subjective. We evaluate and assess the performance of the products we sell at least as hard and generally with a harder eye than our clients do. We have extremely conservative views on what is acceptable and what is not. That doesn't mean we won't sell these products, we communicate the restrictions and describe the positive performance potential - and then it is determined if this product(s) is a fit for that particular user. Digital backs have been sold with ISO ranges from 50 - 800 for years. Have we ever recommended to anyone that ISO 800 is usable? Never. Check my post history and you'll see that I commonly refer to legacy digital backs as ISO 50-200 usable range products. When it comes to crosstalk effects and other anomalies with shifting lenses and digital backs, or even straight up lens performance without shifts, we're extremely critical with our assessments. And our clients use these products in many different ways. Ultra wide creates more challenges. Moderate wide may produce perfectly acceptable results. That is part of the conversation as well. These products can work for you, but it depends on what you are using, how you are using it, and what you are trying to accomplish. That's all part of the conversation. So - we don't see that selling these products is a matter of living up to our standards - in general they all exceed our standards, but all products have performance restrictions - it is important for users to understand the restrictions, if for no other reason than choices at the high end are not as abundant as choices at the low end.
All this has to be discussed in detail with a prospective purchaser of these systems. I realize you may be referring to dealers in general and not Capture Integration, but that only underscores how complex these products are in their use and their expected and actual results. Dealers should be better informed by manufacturers, dealers should be more concerned about initiating their own knowledge base regardless, but also, this is not easy or without a requirement of significant resources and commitment to sell these systems, and that certainly limits the availability of good dealers as much as anything. It is nothing like selling a simple Canon (or even Pentax) system.
Sorry for the long winded post. :-)
Your post is quite helpful, and thank you for taking the time to write it.
There are two different perspectives being offered here: Anders is looking at it (if he'll forgive me for summarizing) as a systems issue, and expecting (as one might) that the linkages of all the parts should be addressed somewhere in the development of all the pieces. Certainly for a $30-50k group of parts, his expectations are reasonable. Its not like a $1k box of computer parts to be assembled.
And yet… this hasn't happened fully. In some cases, manufacturers have closed their systems and tried to control what happens in their domain, something both admirable (they are taking responsibility) and not (it runs against our desires for open systems).
In the days of film, this was a line delightfully blurred: some manufacturers took high levels of interest in complete system precision, to get their customers a reliable solution, regardless of the number of bits and parts. One can only help but be amazed looking at Leica, Hassy, and Rollei, even Nikon and others, for the extensive range of their systems. And the savvy photographer showed his skill knowing how to tweak the systems, mix and match, and get working solutions where others might not.
In this new era, the interface between all these parts falls differently, and its not always clear on whose shoulders. Some fall on the back and camera maker (not always the same) but too often, the responsibility for the interface falls on the consumer. This is more the case in tech cameras, with lenses from one maker, bodies from another, and backs from a third. In some cases, good dealers (C1, DT) step up to the plate and work hard to hold the pieces together. They offer this as the value-added part of their services, and it is extremely worthwhile.
Anders has not had the experience of those dealers (one recalls the difficulties with his digital back), but there are many here in the US who have benefited. One can understand how the supporting dealer might object to being grouped with the general complaint of "bits and pieces" not fully coordinated - they are working to address this problem. They are part of the solution, not the problem.
Its not an easy situation. One is reminded of Doug Peterson's chart of cameras and lens compatibilities, and how much criticism he got for combinations that were not included. It gives one pause - there are more variables than players working to resolve them.
The focus on crosstalk is (IMHO) quite welcome, and it may be that Anders has tumbled onto a something overlooked or not well described. It certainly seems to be a beneficial insight, and goes a long way to explain in simple terms what some of us have experienced. However, we should not overlook all the other bits and pieces that are part of the puzzle, and that some dealers (and others) are helping us to figure out how to work them all together.
In short, two perspectives. Hopefully calmly discussed. Also sorry for long-winded….
My observations has been though that the information how sensor+lens play together and what-is-what (difference between recoverable casts and irrecoverable casts) is not very wide-spread, not among photographers and even not among designers. I hold up SK28 as one evidence of that -- the optical designers at Schneider cannot have tested that on 6um Dalsa although the leading products on the market were already using it, and I think the Cambo Actus is another evidence of the same, I find it unlikely that Cambo would have designed this camera in this way if they were aware of the wide angle limitations. This disconnect between sensor, lens and camera body designsers is a mystery to me.
It's easy for me to say as a layman on the side, but I do it anyway; I think that if I had been a dealer I would not market the Cambo Actus, because it can't hold what the design promises. For the same reason some dealers have pulled the SK28 from the shelf. Sure you can use it with longer lenses and not shift the wides and/or shoot B&W but it's a strange package. But as long as you inform your customers with the limitations so they can make an educated decision it's of course okay.
My skepiticism towards this camera is however based on this. Anyway, I think the best thing that could happen in tech cam land is that a tech-wide friendly CMOS digital back appears, which would make the Cambo Actus to a great concept combined with lightweight (and in comparison affordable) Schneider wides you get a small light view camera with flexible movements and very easy to use thanks to live view. Until then, I think it's a severely crippled concept.
Anders - we hope for the same things! Closer collaboration between the various manufacturing elements would be helpful - perhaps the P1/Alpa relationship contributes to that.
Regarding the Actus - this is a good example of how a subjective viewpoint can produce a limited perspective. Just this morning, I had a call from a good client (Nye) who asked about the Actus. As we discussed it, we touched on the restrictions that the sensor would place on the lenses (I said that just for you, Anders, so you'd know I attached the appropriate responsibility!)
I told him this product - at least at this time - is not an ideal scenic shooting solution for use with his Sony A7R. As we discussed where the lines were drawn on the use, he specified that he doesn't shoot wide landscapes anyway, he shoots with medium and longer lenses. So - his interest remains. It's a good lesson that products don't always fit into the expected box. And actually, his desired use of the camera could be exactly what Cambo had in mind when producing it - realizing the limitations, perhaps. And if sensor design takes a positive step forward with regard to the issue of crosstalk, Cambo has already a good design in place to take advantage of that.
Would it be a reasonable request to ask for a recommendation list of focal lengths for the actus, perhaps explaining with a few words the ins and outs of wider lenses as well?
You guys need to consider that there are people around who are new to the tech camera world but potential prospects.
I would have fallen straight into a trap with the actus and wide angles if it were not for this discussion here.
Thanks for that.
I'd like to see such a list as well. Although I personally know the digital tech lens lines quite well, I don't know much of what's available in the Mamiya RZ and other adaptable lens lines.
From analysis I've done on raw files I've got the general recommendation I would give for a Sony CMOS MF sensor (CFV-50c, H5D-50c, Credo 50, IQ150, IQ250) is to not exceed about 30 degrees (60 degree cone) to avoid getting too much of the irrecoverable crosstalk. For horizontal orientation you may be able to stretch it a few more degrees. This does not mean than below 30 degrees there is zero crosstalk, just that there is an "acceptable level" of crosstalk below this angle, ie generally not possible to see any artifacts even if you search for them. Naturally this is based on my judgement, a different person could judge otherwise.
For symmetric lenses you should be able to approximate with simple trigonometry, <image circle diameter> = 2 x <focal length> x tan(<acceptable crosstalk angle>).
A few examples, SK28 = 32mm image circle (smaller than the sensor), SK35 = 2 x 35 x tan(30) = 40mm, SK43 = 2 x 43 x tan(30) = 50mm, SK60 70mm, SK72 85mm.
That is you need to get up to almost 80mm focal length before you have a full 90mm image circle with stable performance, in practice it's a bit less though as you won't shift to hard vignetting and the sensor corners can reach a bit farther than 30 degrees thanks to offset microlenses. The SK72 should be 100% usable, while you really can't use the full 110mm image circle of the SK60, but you might not like the sharpness falloff out there anyway. Depending on your taste and the scene you're shooting you can also stretch it further into the crosstalk zone, the image circle examples above is probably more conservative than many dealers would recommend from their testing. Of course, it's also a matter of taste how much image circle you need to be satisfied with the available movement range.
The 44x33mm sensor has 55mm diagonal, for center shots you can undercut a bit thanks to offset microlenses and better crosstalk suppression in short side direction, the 43mm work just fine in center (despite the 50mm image circle in the calculation above) and maybe even the 35mm but I doubt that (I have no test shots for that lens so I cannot sanity check that).
Note that there's no gradual degradation like vignetting, when you shift beyond a certain limit you can get a quite sudden breakdown, more so than on the CCD sensors. I think this is due to the offset microlenses (actually offset photodiodes), but I'm not sure.
Not all lenses are symmetric though. When it comes to retrofocus lenses it may not be so easy to figure out at what angle they deliver the the light, it's unfortunate that it's not available in the data sheets. If you have the lens you can measure it using a laser pointer, a piece of paper and careful perpendicular setup. I don't really know what the data on the Rodenstock Digarons are, but I do know that the Rodenstock 32mm is more retrofocus design than the Rodenstock 40mm, so it may not be as simple that the longer focal length increases usable image circle.
A good test to see if you get irrecoverable casts is to shoot two LCC shots, one with red filter and one normal neutral white. Apply the white LCC on the red, if it's not flat red with even saturation and color then you're having irrecoverable color cast (ie crosstalk). The advantage with this type of test rather than a real shot is that it's less risk that you happen to shoot a scene where crosstalk doesn't notice much and then over-estimate the image circle and get disappointment later on when you shoot another scene. A real scene shot is good to see how far you may be able to stretch it without noticing too much, while the artificial shots are good to document the actual performance so you know in which range you can trust the system regardless of the scene contents.
Last edited by torger; 19th September 2014 at 02:59.
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It's very much to our benefit, and within our capability, to make sure the full solution is the best one for you.
A comprehensive list of every possible sensor, lens, movement, and focus distance is simply not practical. Even a 28XL and IQ250 (which normally would be a complete non starter for several reasons) would work beautifully on this system - IF you were using it for macro table-top special effects (this is an extremely obscure use-case only being used to illustrate the broader point that there are several variables). But we (DT), and other tech-camera oriented dealers like CI, work every week with clients to test specific combinations, provide rentals which count toward purchase, provide studio space and equipment for those who want to do their own testing but can't arrange insurance for a rental, and have extensive overall experience to help provide very good guidance if none of the above is practical (e.g. the combination is not possible to get without purchase because it is too obscure or one-off).
One published test set you can parse yourself is here. That is specific to a handful of lenses we could gather the same day we had an early IQ250, and is relevant largely to infinity focus distances. We have done other testing in-house and had clients share results from many other kinds of combinations.
this post from when I worked at CI in 2011). I considered such a technical conversation way too technical for practical discussions; I had used instead terms like "color cast which is not fully recoverable". Somehow by giving it a name (despite the name being very technical sounding) more people understood the underlying issue, which is what matters. In some ways it served as branding for the issue to raise awareness of it so instead of saying "color cast which is not fully recoverable leading to a loss of color fidelity" you can just say "cross talk". For that we must all give Torger credit.
Still, I prefer, wherever possible to avoid overly complicated/technical conversations and focus on practical testing and metrics (e.g. up to 10mm of movement with X back and Y lens, or "significantly less movement than X+Y combination) and on providing the opportunity for personal evaluation.
From my point of view, yes the issue had been discussed previously but from some reason from those past discussions I always came away thinking it was the lens and or image circle causing the issue. Instead as I have learned from reading and my own testing, it's more due to the sensor involved and the degree of micro lenses on the sensor that cause the light splitting when the light hits the sensor at an angle due to movements. As shown the 50MP kodak in the Hasselblad and 39MP Kodak in the P45+ show very little if any problem with this but do show light falloff as expected.
The 60 and 80MP Dalsa chips have a bigger issue but with most lenses it seems recoverable. There are known exceptions to this with the 80MP Dalsa. Considering everything the Dalsa chips do a very good job but just can't be called on for much of a push from base ISO.
The 50 MP Sony gives a wonderful push in ISO but is much more effected by the color fall off with wides with even small movements. Which is unfortunate as due the 1:3 crop in many shooting situations pushes the photographer to a wider lens. It would for me.
It's my first post here.
I'm glad I found this thread.
It looks like Cambo is not alone in this matter.
Take a look this video at 15th sec.
Horseman Axella - YouTube
Hey, here is a quick link to an interesting paper on this topic showing the issue of micro lenses design and colour issues.
PS found by google
This thread has taken an interesting turn, it almost seems like the dealers and mfg are getting blamed for not informing buyers about the crosstalk phenomenon which could not be further from the truth. I recall a P1 tech note on this issue dating back to before the P65+.
I personally was informed about it by Steve at C1 before I upgraded to the P65+ and Dave G made a personal call telling me the issue would be exaggerated if I purchased the 180.
Hardly seemed swept under the rug to me. The benefits of the tech cams outweighed the headaches dealing with it.
Now that is my experience, others may vary but the issue and reasons for it has been publicly discussed for sure.
Ed Cooley Fine Art Photography
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I also have chime in here. When I went into the tech camera CI - Chris and Dave were very clear - that since I had a 180 back, the size and angles of the pixels on sensor, I would need Rodenstock Lenses as they were retrofocus, although heavier and more expensive to buy and to add Tilt shift (Cambo) was also an added expense.
Neither Dave or Chris (or Sam) would have sold me any SK lenses to pair with the 180 under 60mm. Also when I bought the 180 back with the DF Chris pointed out to me if I decided to go into tech, it would cost me more for lenses than if I bought 140 or 160 back. This is a fact.
When I bought the 28mm LS for the DF, Steve made phone call to me in China to remind me again, to make sure I knew I was buying a great 30mm lense, but as 28mm - well the corners will not be as sharp as the rest of the frame.
Also Rod Kulkas of Arca Swiss is 100% honest, 100% knowledgeable. Has given only the best of advice.
None of the above EVER me feel like I had stupid questions and always went out of their way to not just tell me things but explain the whys and wherefores.
Seems to me that either the dealers in Europe are either not knowledgeable or are more like order fillers. Although Paula of Linhof in England and Robert White have been very open in the few dealing I have had with them.
The limitations and the expertise of pairing lenses to senors is very logical to me. When I bought my Rodenstocks, it was very clear that if a 100 megapixel sensor comes out then there was no guaranteeing they perform as well as they do paired to the 80 MP back.
Personally I would never make this kind of investment without an honest dealer. Just like I would never buy a Ferrari from a used car lot.
With my experiences I find it an injustice that Steve from CI has to defend his Company.
I can not speak for Phase, as I have very little dealing with them directly in Denmark (although the few dealings have been positive). Cambo, and Arca Swiss, and even with the local Phase and Canon offices, this is as good as it gets.
Personally I am proud to consider the people I have named above as friends. They helped me make the right decisions, and also taught me things. Just as I have learnt from the posts on GetDPI forum
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