stephengilbert
Active member
Okay, I have to ask. Can someone give an example of a situation in which the Arca focus precision allows a user to do something that can't be done with an ALPA or Cambo?
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In theory yes. A very fine focus stack for example but in reality this thread is starting to sound like because the Arca has a finer focus system it renders the Alpa/Cambo system inferior. I don't think for the average landscape shooter the differences really matter that much as looking at the standard of work shown on here, both focus methods are proven to work extremely well.
Guy Mancuso
Administrator, Instructor
Agree and it's not what we want our commercial vendors doing. In Another words I had enough. Hope my point comes across very clearly here. Thanks Guy
Don Libby
Well-known member
I've been a very proud Cambo shooter now for several years and have never felt I was using an inferior product thus have stayed away from commenting.
Jack summed it correctly "Agreed in that whatever works best for the individual is what they should choose." Using a tech camera of any manufacture requires precision; some companies are offering slightly better precision than others. I've seen a lot of the added gizmos (my term) that are added to the camera to aid the shooter sometimes to the determent of the art (art of using a tech camera).
Regarding which focus is best I submit that the photographer needs to know his/her equipment which can only be done by full hands on testing by themselves. I personally have never had a lens fail me. I on the other hand have failed the lens by not following a strict workflow pattern.
As many of you know I recently upgraded to a P65. I mention that as before I saw flecks in the sky as I shot landscape. Those flecks have turned out to be birds. This impresses the hell out me for multiple reasons; the quality of the lens and resolution, as well as the resolution of the P65.
The original question that started all this discussion was "...comparison (IQ) between a tech camera setup and a MF DSLR...".
If you were shooting with the same digital back and the only difference was the tech camera with lens vs. a MF DSLR then I'd answer the IQ will be better with the tech camera. I saw this myself shortly after getting the Cambo and before I sold my Phase 645 and all the lenses.
Just my 2¢ here...
Don
Guy - just saw your post after I posted mine...hope I don't offend.
Jack summed it correctly "Agreed in that whatever works best for the individual is what they should choose." Using a tech camera of any manufacture requires precision; some companies are offering slightly better precision than others. I've seen a lot of the added gizmos (my term) that are added to the camera to aid the shooter sometimes to the determent of the art (art of using a tech camera).
Regarding which focus is best I submit that the photographer needs to know his/her equipment which can only be done by full hands on testing by themselves. I personally have never had a lens fail me. I on the other hand have failed the lens by not following a strict workflow pattern.
As many of you know I recently upgraded to a P65. I mention that as before I saw flecks in the sky as I shot landscape. Those flecks have turned out to be birds. This impresses the hell out me for multiple reasons; the quality of the lens and resolution, as well as the resolution of the P65.
The original question that started all this discussion was "...comparison (IQ) between a tech camera setup and a MF DSLR...".
If you were shooting with the same digital back and the only difference was the tech camera with lens vs. a MF DSLR then I'd answer the IQ will be better with the tech camera. I saw this myself shortly after getting the Cambo and before I sold my Phase 645 and all the lenses.
Just my 2¢ here...
Don
Guy - just saw your post after I posted mine...hope I don't offend.
Terry
New member
Stephen, I don't know if this qualifies. When I got my IQ180 I was trying to work out focus on my 43xl. So, I went to the marina where I had lots of things at all different distances and wanted to see what was going on. A few things to note. This was a focus test so I didn't bother correcting all files with an LCC. I also think as others do that you can get good results with all of the systems. The question becomes how easily and what is the best work practice for the person. I just know for me the Arca gives me a lot of precision when focusing. I did the same test at a distance of 3 feet and that means very large movements on the helical for a huge leeway for fine tuning.
Here are the two things in my opinion where I think Arca works well. I don't have enough experience with other systems to make any categorical statements. Here is the original shot.
I took a whole series of shots at 0, 1, 2, 3, 4, 5 on the focus helical. Please note each of those would be a big increment and I have a lot of room to fine tune between these numbers (go back to Jack's post and math). the first two crops on the left look pretty close and they are full number apart. As I came to see what I was getting I then moved in to test in smaller increments like 1,1.4,1.8, 2.2 I just don't have all those files easy to line up right now.
So here are the differences in a screen shot of the overlayed exposures
So, my two take aways from the Arca system is the way it focuses I get good focus without shimming the back and secondly there is a lot of room to fine tune the focus.
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If one takes a look at the back of a Phase back, one might notice four shiny spots.
Those spots are lapped, meaning they are ground flat and are designed to be what establishes the reference from the sensor plane for distance and parallelism.
Precise cameras that attach that back ought to have four similar spots, also lapped, arranged to contact the corresponding points on the back. If that has been done well, the back and camera are "zeroed in" and sensor will be at a known reference in parallelism to the lens board and at known distance from the helical.
Some vendors provide shims to adjust these points either because they have not lapped them to the necessary degree of precision or because they have found that their is enough variation in their bodies to warrant this.
That is totally ok, but others might not need this adjustment, or might use another mechanism for adjusting the distance such as an arbitrarily numbered scale on the helical.
The ONLY potential advantage to the shimming approach is that it allows for a greater degree of manufacturing variation in the camera body so that it can be brought into tolerance with shims. Of course along with shims comes the variation that various pressures will have on the thickness of a pile of shims given oil coatings, flatness, and so forth.
There are plenty of ways that a body may be built, but castings are generally less precise than bodies that are machined out of bar metal unless they have had thei critical dimension machined.
Bottom line is that I can trust or adjust a body to suit my needs, so the remaining distinguishing characteristics of Tech cameras (besides movements, lets not discuss them at the moment) is the helical or other focusing mechanism and the quality of the lenses themselves.
-bob
Those spots are lapped, meaning they are ground flat and are designed to be what establishes the reference from the sensor plane for distance and parallelism.
Precise cameras that attach that back ought to have four similar spots, also lapped, arranged to contact the corresponding points on the back. If that has been done well, the back and camera are "zeroed in" and sensor will be at a known reference in parallelism to the lens board and at known distance from the helical.
Some vendors provide shims to adjust these points either because they have not lapped them to the necessary degree of precision or because they have found that their is enough variation in their bodies to warrant this.
That is totally ok, but others might not need this adjustment, or might use another mechanism for adjusting the distance such as an arbitrarily numbered scale on the helical.
The ONLY potential advantage to the shimming approach is that it allows for a greater degree of manufacturing variation in the camera body so that it can be brought into tolerance with shims. Of course along with shims comes the variation that various pressures will have on the thickness of a pile of shims given oil coatings, flatness, and so forth.
There are plenty of ways that a body may be built, but castings are generally less precise than bodies that are machined out of bar metal unless they have had thei critical dimension machined.
Bottom line is that I can trust or adjust a body to suit my needs, so the remaining distinguishing characteristics of Tech cameras (besides movements, lets not discuss them at the moment) is the helical or other focusing mechanism and the quality of the lenses themselves.
-bob
Guy Mancuso
Administrator, Instructor
Not at all Don.
Here is my take . Btw I have not bought a tech cam YET but I have used all three systems and some nice gear for sure and in general very precise tools . But let's face it easier to focus no question a MF DSLR pick your brand it's easier than a tech cam period. Now precisely if you look at our olderanual focus lenses from our 35mm days . Any lens compared to any other lens with the same focal length the longer the focus the more precise you can get the focus easier and fine tune better. Nothing changed here with tech cams or even view camera the more travel you have the better nailing the focus. This is just logic. Same rules apply with a tech cam. Think a 85mm canon 1.2 with the long focus compared to a canon 85 1.8 with a shorter throw. The 1.2 you can achieve a more critical focus
Here is my take . Btw I have not bought a tech cam YET but I have used all three systems and some nice gear for sure and in general very precise tools . But let's face it easier to focus no question a MF DSLR pick your brand it's easier than a tech cam period. Now precisely if you look at our olderanual focus lenses from our 35mm days . Any lens compared to any other lens with the same focal length the longer the focus the more precise you can get the focus easier and fine tune better. Nothing changed here with tech cams or even view camera the more travel you have the better nailing the focus. This is just logic. Same rules apply with a tech cam. Think a 85mm canon 1.2 with the long focus compared to a canon 85 1.8 with a shorter throw. The 1.2 you can achieve a more critical focus
Guy Mancuso
Administrator, Instructor
Damn iPhone
Guy,
Let's not confuse precision with accuracy or repeatability.
If i were to take say an arca or an alpa I am much more able to set up a precise and repeatable focusing distance than is possible with the DF or the cambo assuming that the temperature were reasonably constant.
The tech camera shooter might have this very repeatable setting but might have no real idea of the actual distance that it might correspond to. That is one reason that testing and calibration shots are needed.
The DF on the other hand, might give you a fair degree of average accuracy with not a whole lot of precision or repeatability.
Photographers for ages have used DOF to "cover up" this focusing ambiguity.
with COC shrinking from the traditional .003mm to twice pixel pitch (or maybe sqrt(2) times pixel pitch have effectively crushed this tolerence down and sought improved degrees of both precision and accuracy.
-bob
Don Libby
Well-known member
Totally agree Guy. The differences between a MF DSLR and Tech was brought home (again) while Ken & I were shooting almost side by side in the slot canyons. The difficulty of precise focusing on a tech camera (any tech camera) is part of the reason using one is such a slow process. However - the image quality of an image taken with a tech camera done right will blow your socks off.
Here's a sample of a 2-image focal stack from last week. While the end result is somewhat pleasing if I had to do it over again I would have added a 3. Whether 2 or 3 it would have been the same. I use a Leica D5 for precision measuring then transferring the measurements onto the lens I set the focal point accordingly. I've done similar without the aid of a laser by guessing the distance and shooting 4.
Here's a sample of a 2-image focal stack from last week. While the end result is somewhat pleasing if I had to do it over again I would have added a 3. Whether 2 or 3 it would have been the same. I use a Leica D5 for precision measuring then transferring the measurements onto the lens I set the focal point accordingly. I've done similar without the aid of a laser by guessing the distance and shooting 4.
Guy Mancuso
Administrator, Instructor
Bob I kind of said that wrong to be honest and was going to delete it. I just cant get a iPhone to work like I think. LOL
Drinking all day at a pool resort don't help either. LOL
Drinking all day at a pool resort don't help either. LOL
Don Libby
Well-known member
That's okay just so long as you wern't driving and texting ....:ROTFL:
Guy Mancuso
Administrator, Instructor
Two areas for me Stephen: First is minor: allowing me to define a few different "infinity" focus points -- ie; 360 meters or 180 meters, or 90 meters. With the Arca I can hit these pretty precisely at f8, and while not impossible is going to be more difficult with a tradition tech helical. Will the differences be significant in a large print? Certainly not if you don't have the three versions to compare, but maybe yes if you do
. Second and more significant for me, is when you impart tilts to alter PoF. Here minor changes in your focus point can have significant impact on how that PoF renders through the frame. This gets more critical as lenses get shorter. So my net is this: if you use tilt and especially with wide lenses, it can be a positive benefit to have finer control over your exact focus point.
That's all my original point was. I will repeat for the 3rd (4th?) time that all of these systems are of great quality. I've used them all and all are capable of making outstanding images. Moreover I repeat that I believe shooters should use what benefits *their* working methods and styles first and foremost. And for me and *my uses*, I know the best option is the Arca for the reasons outlined earlier (tilt or swing with all lenses and both rise and fall movements at the back).
Hope that clarifies,
PS: And I agree with what Terry, Bob, Guy and Don are saying here -- we are all on the same page
wentbackward
Member
Don't worry we'll all be bored of sharpness and absolutely image quality soon enough and start wondering how we can pull and contort our gear ala Nick Brandts animal portraits, which, despite the innaccuracies of pulling the lens of a Pentax, is some of the most wonderful photography in history.
On a serious note, I was wondering, after I have shimmed the Alpa max for one lens, are all lenses infinity stops really that accurate that the same shimming is fine for all lenses?
On a serious note, I was wondering, after I have shimmed the Alpa max for one lens, are all lenses infinity stops really that accurate that the same shimming is fine for all lenses?
stephengilbert
Active member
"I have shimmed the Alpa max for one lens, are all lenses infinity stops really that accurate that the same shimming is fine for all lenses?"
That's what they say. According to ALPA, the shimming corrects for slight differences in the registry of the backs. But I wouldn't be surprised to hear some claim that the infinity stops can vary as well. :angel:
That's what they say. According to ALPA, the shimming corrects for slight differences in the registry of the backs. But I wouldn't be surprised to hear some claim that the infinity stops can vary as well. :angel:
Christopher
Active member
I just wanted to write a last part here. I personally think that both the Alpa and Arca are amazing products. When I made my decision a while back, I tried both cameras and it was a very close call. I am pretty sure that I could live with both cameras, for me the main point going with the Arca was the better lens shade system and tilt for ALL lenses.
This does not make the Alpa a worse camera, it is still a fantastic system especially if one wants a tech and a walking around camera.
That's all and I think I'm done in this thread.
This does not make the Alpa a worse camera, it is still a fantastic system especially if one wants a tech and a walking around camera.
That's all and I think I'm done in this thread.
P
Porpoise
Guest
It's not about the accuracy of the tool but how you use it.
The Arca moves 2.5mm on one turn, divided by 172 marks. best we can do is probably half a mark which should move the lens .0073mm. For the Alpa this seems to be .017mm per half degree turn. Let's just assume the rest of the system doesn't degrade this precision.
The following results are again for a 40mm lens at f/4. If we try to focus at 10m and have to live with the "inaccuracy" of the Alpa, we might be focusing anywhere between 9.51m and 10.55m. As I explained in a previous post, we should look at the range of maximum resolution. These would be 8.46-10.85m or 9.28-12.23m. This range increases rapidly at larger distances and 77m is hyperfocal for f/4 meaning maximum resolution from 38.5 and beyond. Focusing for 10pm at f/11 gives 7.37-15.56m. No need to worry about .5m more or less.
Setting a 10m distance on the Alpa seems accurate enough for max resolution at 10m and we get some nice DoF front and back. Plenty of room for focus stacking too. At this distance your IQ180 can resolve objects of 1.3mm, while good eye vision resolves 4.0mm. So I am already taking pictures of details I can't possible see without binoculars.
If you for some reason would like more control over the range of maximum resolution, please remember: a difference of 10 degrees Celsius (18 Fahrenheit) will cause 40mm bronze to expand/shrink .007mm. So whether you are using an Arca or an Alpa, do not forget to adjust for temperature unless your lens has any kind of temperature compensation which I doubt.
Jack, focusing on 360m at f/8 gives you maximum resolution from 34.7pm and beyond. Focusing at 90m makes maximum resolution start at 26.9m. You should see no difference between the focus settings for any objects beyond 34.7m. Lens movement should be .0133mm. That is .9 mark on the Arca and .4 degrees on the Alpa. It might be easier to just warm up the lens 19 degrees. ;-)
I for one believe the lovely rosewood handle on the Alpa is more important than the possible difference in accuracy. Accuracy is plenty on both camera's.
Hans (still no geek)
The Arca moves 2.5mm on one turn, divided by 172 marks. best we can do is probably half a mark which should move the lens .0073mm. For the Alpa this seems to be .017mm per half degree turn. Let's just assume the rest of the system doesn't degrade this precision.
The following results are again for a 40mm lens at f/4. If we try to focus at 10m and have to live with the "inaccuracy" of the Alpa, we might be focusing anywhere between 9.51m and 10.55m. As I explained in a previous post, we should look at the range of maximum resolution. These would be 8.46-10.85m or 9.28-12.23m. This range increases rapidly at larger distances and 77m is hyperfocal for f/4 meaning maximum resolution from 38.5 and beyond. Focusing for 10pm at f/11 gives 7.37-15.56m. No need to worry about .5m more or less.
Setting a 10m distance on the Alpa seems accurate enough for max resolution at 10m and we get some nice DoF front and back. Plenty of room for focus stacking too. At this distance your IQ180 can resolve objects of 1.3mm, while good eye vision resolves 4.0mm. So I am already taking pictures of details I can't possible see without binoculars.
If you for some reason would like more control over the range of maximum resolution, please remember: a difference of 10 degrees Celsius (18 Fahrenheit) will cause 40mm bronze to expand/shrink .007mm. So whether you are using an Arca or an Alpa, do not forget to adjust for temperature unless your lens has any kind of temperature compensation which I doubt.
Jack, focusing on 360m at f/8 gives you maximum resolution from 34.7pm and beyond. Focusing at 90m makes maximum resolution start at 26.9m. You should see no difference between the focus settings for any objects beyond 34.7m. Lens movement should be .0133mm. That is .9 mark on the Arca and .4 degrees on the Alpa. It might be easier to just warm up the lens 19 degrees. ;-)
I for one believe the lovely rosewood handle on the Alpa is more important than the possible difference in accuracy. Accuracy is plenty on both camera's.
Hans (still no geek)