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Questions for Cambo Actus owners

larkis

New member
I'm looking at getting one of the Actus units for using with my sony and soon the GFX 100s but would like to know a few things from anyone who owns one:

1) Does the setup effect sharpness/resolving power since the lens is further away and the image circle is increased.
2) Are chromatic aberrations/fringing a problem when tilt/shift is involved ?
3) Are there any other major issues to consider that are not usually talked about ?

I want to use the Actus camera as a replacement for my 4x5 for shooting landscapes.

Thank you in advance.
 

orftoden

Member
I shoot an Arca Swiss m-line 2 with the 100s, so while it's not an actus, it's close enough for me to provide some insight.

1) No. Resolving power is a function of the lens used. If you pair the actus with good glass, it will deliver. However, I have found that extra attention must be made to absolutely nail the focus or your IQ will suffer. Similarly, with MF, you will need to stop down no higher than say f/8 to f/11 before diffraction impacts sharpness. This isn't a huge issue, because front tilt will allow you to overcome this particular obstacle.
2) CA on the lenses I have used is not as bad as I was expecting. The only lens I have noticed a real issue is the Schneider 28mm digitar. However, it can be removed easily in post. Sometimes this means clicking the remove CA button. Other times you can remove it using an ICC profile. I would say it is something to consider, but if you're willing to work around CA, it's not a huge issue.
3) Like with using a 4x5, this combo will slow your work down tremendously. Also, it's probably not a good option if you find yourself shooting in bad weather. It is not the lightest setup and 100% requires a tripod at all times. However, for shooting landscapes, all of these drawbacks are worth having the ability to shift and tilt.
 
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rdeloe

Active member
A major issue, especially if you use a GFX 100S, is the availability of suitable lenses with shorter focal lengths. Review the information provided by Cambo. They cross-reference lenses with sensors. In a nutshell, you're going to be limited to wide angle lenses from medium format systems (e.g., Pentax, Hasselblad, Mamiya). The widest practical option that isn't a fisheye and that isn't very rare and very expensive is the SMC Pentax-A 645 35mm f/3.5, or the later DA version. From 55-60mm and longer, things open up considerably.

Note, there are a few recent and live threads that explore wider options on the 100S.
 

vjbelle

Well-known member
I have two Cambo Actus setups. A DB+ which is dedicated to my Phase and the other, a GFX version, which I can use with my Phase, GFX 100s and Sony 7RM4. With regards to your first question you have nothing to be concerned about. The FFD is lens dependent and is a constant across all digital backs/cameras you would attach to the Cambo. Sharpness and resolving power is not affected. The 100s is no further away than any other back or camera that would be attached to the Cambo. CA and Fringing is also very lens dependent and will not be effected by the Cambo any more or less than another system.

As Rob pointed out there are serious roadblocks regarding wide solutions. I can shoot my Schneider 60Xl but am limited to 6mm of movements in one direction at a time because of the physical interaction between the bellows mount and the rear element of the Schneider lens. That, so far, is the widest I can get and reach infinity. This is not an issue for me since I mostly shoot in the 60mm to 100mm range (35mm equivalent). I also have my Phase 4150 for those rare times I would need movements in the wide range.

You will have to be very careful with regards to parallelism of the standards. You can rely on the visual markings on the front standard for swing and tilt but even those settings will get you close but not dead on. You can't even remotely be cavalier regarding this as your image will/can show focus variations from left to right/ top to bottom.

Regards,

Victor B.
 
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larkis

New member
A major issue, especially if you use a GFX 100S, is the availability of suitable lenses with shorter focal lengths. Review the information provided by Cambo. They cross-reference lenses with sensors. In a nutshell, you're going to be limited to wide angle lenses from medium format systems (e.g., Pentax, Hasselblad, Mamiya). The widest practical option that isn't a fisheye and that isn't very rare and very expensive is the SMC Pentax-A 645 35mm f/3.5, or the later DA version. From 55-60mm and longer, things open up considerably.

Note, there are a few recent and live threads that explore wider options on the 100S.
I happen to have the (updated) 35mm f3.5 Pentax lens, but also have the 25mm f4 Pentax 645 lens (the one with the inset filter). While it's rather large, do you think that one could work ? I usually don't shoot wider than 35mm. My favourite lens on the 4x5 when I was using it a lot was a 210mm Nikkor and a 135mm Shneider.

What would a Sony GM 24mm turn into ?
 

rdeloe

Active member
I happen to have the (updated) 35mm f3.5 Pentax lens, but also have the 25mm f4 Pentax 645 lens (the one with the inset filter). While it's rather large, do you think that one could work ? I usually don't shoot wider than 35mm. My favourite lens on the 4x5 when I was using it a lot was a 210mm Nikkor and a 135mm Shneider.

What would a Sony GM 24mm turn into ?
It's that 25mm Pentax 645 lens I had in mind when I said "widest practical option" ;). I've never tried the 25mm. There are two versions: the DA one that only covers 33mm x 44mm, and the older D-FA, which covers 645. You'd want the D-FA to allow movements. Alas, neither has an aperture ring. You can buy an adapter that allows controlling the aperture (it's the one Ed mentioned -- e.g., from Fotodiox). However, that device is meant to mount the lens to a GFX camera, not to a Cambo Actus. I believe the Actus Pentax 645 mount board is for the "normal" Pentax lenses that have aperture.

On my outfit (not an Actus -- but similar idea: a digital view camera that serves as the "adapter" for a GFX 50R), I use 35mm a lot and consider it quite wide. I've never had a taste for much wider angles of view, always preferring normal, a bit wider than normal, and a bit longer than normal.
 

Audii-Dudii

Active member
You will have to be very careful with regards to parallelism of the standards. You can rely on the visual markings on the front standard for swing and tilt but even those settings will get you close but not dead on. You can't even remotely be cavalier regarding this as your image will/can show focus variations from left to right/ top to bottom.
This has been my experience as well; so much so, in fact, that I ultimately put my Actus aside and rarely use it because I only need rear rise / fall for the majority of my photos and there are other cameras that are a better fit for my purposes.
 

Gerd

Member
The Pentax DF-A 645 25mm is unfortunately completely useless outside of 44x33 (and it wasn't particularly good at the edge).

I tried the exact combination with IQ3 100 Tr. Years ago. I immediately discarded it.

Greetings Gerd
 

GrahamWelland

Subscriber & Workshop Member
I love my Actus which can accommodate both my GFX and MFDB. TBH I pretty much only shoot with my IQ4150 with the Actus and hence have no limits on the lenses available to use with the system vs using the GFX which has more restrictions.

If you want tilt / swing and rear rise / fall then it works well. As Victor mentioned, the trickiest issue is ensuring that the front standard is absolutely square to the back otherwise you’ll get unintended swing which is very noticeable with high resolution backs/cameras. For ultimate focus accuracy I use the upgraded controls from Cambo for finer resolution when moving the rack on the rail. Ditto for tilt.
 

Cambo

Member
" I believe the Actus Pentax 645 mount board is for the "normal" Pentax lenses that have aperture. "
The Pentax 645 lens board for the Actus has its own lever to enable aperture settings when using lenses without aperture ring. And there is the option to shoot wider than the aforementioned 25mm with a GFX-100: The Actar-19.
 

Attachments

I love my Actus which can accommodate both my GFX and MFDB. TBH I pretty much only shoot with my IQ4150 with the Actus and hence have no limits on the lenses available to use with the system vs using the GFX which has more restrictions.

If you want tilt / swing and rear rise / fall then it works well. As Victor mentioned, the trickiest issue is ensuring that the front standard is absolutely square to the back otherwise you’ll get unintended swing which is very noticeable with high resolution backs/cameras. For ultimate focus accuracy I use the upgraded controls from Cambo for finer resolution when moving the rack on the rail. Ditto for tilt.
I have the same issue with my actus -keeping the front standard square to the back. Infact I hardly use the movements available on. The front standard and would be more than happy to have to completely locked up- however with that not being possible there is always a slight creep which affects the focus. What controls do we have to counter this problem? Thank you so much.
 

Audii-Dudii

Active member
I have the same issue with my actus -keeping the front standard square to the back. Infact I hardly use the movements available on. The front standard and would be more than happy to have to completely locked up- however with that not being possible there is always a slight creep which affects the focus. What controls do we have to counter this problem? Thank you so much.
There may be other solutions to keep the front standard square, but this was mine:

 
Thank you Audii-Dudii, so you have replaced the front standard with an L-plate? sorry can I bother you for a bit more detail? Thanks
 

Audii-Dudii

Active member
...so you have replaced the front standard with an L-plate? sorry can I bother you for a bit more detail?
I initially started by shortening the Actus base rail to the length of the sliding carriage assembly and then attaching a piece of .250" thick aluminum angle to the remaining piece of base rail and in turn attaching the Actus lens panel to that via a pair of M6 screws (the second of which screws into the opposite side of the aluminum angle and then only partially through it, hence isn't visible in these photos. I would have remade the angle piece so both of the screws weren't visible, but I was too lazy to bother because almost all of the cutting and shaping was done manually using a hacksaw and files, thus took some time...):



I subsequently added some "speed holes" to both legs of the aluminum angle and trimmed the width of its base leg slightly to reduce its weight and painted it with wrinkle-finish black paint:



And then after I gained some experience laminating multiple thin sheets of carbon fiber into a single, thicker sheet as part of another camera project, I decided to shorten the other aluminum leg and then restored it to its original length by attaching a piece of 5 mm thick carbon fiber sheet, which is how the camera appears in the first photo I posted to this thread.

Be warned that since I was working mostly by hand here, getting the aluminum angle aligned sufficiently parallel to the sensor in both the horizontal and vertical planes to avoid introducing an unwanted tilt or swing (which, of course, was the point of undertaking this modification in the first place!) was done via trial-and-error and took quite a bit of time. But by working carefully, it can be done, as I eventually proved!

Of course, if I had access to a mill, precisely and accurately machining this part from an aluminum billet would be an easy task, not to mention one that could be done in a fraction of the time, but one can only work with the resources available to them, eh?

That said, while this approach worked well for me and my purposes (I rarely ever need or use tilt or swing, which is why the inability to lock down the front standard was so frustrating!), I am not necessarily recommending it to others. And if / when I ever decide to sell the Actus, all I need to do to return it to its original form is replace the shortened base rail with an OEM Cambo rail (which cost just over $100 last time I checked, hence the reason I was willing to tackle this project, because I knew I wouldn't permanently destroy its market value as a result.)

Other Actus owners have had some success in this respect by simply tightening the tilt and swing mechanisms, which makes them more difficult to rotate, both voluntarily and involuntarily. I tried this, but ultimately decided to replace the front standard entirely because it also saved something like 13 ounces of weight, which is noticeable after carrying the camera many miles during an outing.
 
Be warned that since I was working mostly by hand here, getting the aluminum angle aligned sufficiently parallel to the sensor in both the horizontal and vertical planes to avoid introducing an unwanted tilt or swing (which, of course, was the point of undertaking this modification in the first place!) was done via trial-and-error and took quite a bit of time. But by working carefully, it can be done, as I eventually proved!

Thank you for such a detailed explanation. I was thinking about the key point here of keeping the new aluminium angle parallel to the sensor. Amazed at your perseverance and versatility. I doubt I will go down that route, however will definitely explore the miil option. I also have a Cambo WRS and was wondering if I could look at fashioning a rear panel that can take a 35mm sensor, like the Sigma FP-L, considering it is a box camera without a grip and could function as a digital back. This way I will get a compact solution with only the movements I desire. I also have the Cambo-WRS to Canon lens adaptor so I can have the TS-E's mounted on this. Thank you once again!
 

Audii-Dudii

Active member
I also have a Cambo WRS and was wondering if I could look at fashioning a rear panel that can take a 35mm sensor, like the Sigma FP-L, considering it is a box camera without a grip and could function as a digital back. This way I will get a compact solution with only the movements I desire.
You mean like this?



Obviously, this can be done (and in many respects, the Sigma FP L is a better choice than the A7R I used) but I ultimately choose to go in a different direction because the WDS was noticeably heavier than I preferred. I refuse to do any "drive-by shooting" so I often end up walking several miles over the course of my outings and after covering six or seven miles, I've found the less a camera weighs, the better!

(If you're curious, I recently posted a photo of my present camera of choice in this thread.)
 
You mean like this?
Obviously, this can be done (and in many respects, the Sigma FP L is a better choice than the A7R I used) but I ultimately choose to go in a different direction because the WDS was noticeably heavier than I preferred. I refuse to do any "drive-by shooting" so I often end up walking several miles over the course of my outings and after covering six or seven miles, I've found the less a camera weighs, the better!
(If you're curious, I recently posted a photo of my present camera of choice in this thread.)
Wow! I really admire your tenacity to work things out and get your desired result. I had a much simpler solution in mind...really not sure if it can work that way. I will definitely check out the other thread. Thanks once again.
 

Audii-Dudii

Active member
Wow! I really admire your tenacity to work things out and get your desired result.
Tinkering with cameras is my other hobby these days ... lol. And although I still don't have access to a mill or a lathe, I do have a small drill press and one each belt and disc sanders, and it often surprises just how much one can accomplish -- with sufficient accuracy and precision -- using just these limited power tools and basic hand tools. For these projects, the primary benefit of using power tools is being able to perform the same task in a small fraction of the time that would be required using only hand tools. Provided one works slowly and carefully, achieving good results is often just a matter of taking the time necessary to do so and not rushing things.

I had a much simpler solution in mind...really not sure if it can work that way.
In my previous response, I should have noted that because of the thickness of the WRS to Canon lens adapter, combined with the Sigma FP L's 20 mm FFD, I don't think you can make them work together (i.e., focus EF lenses at infinity) when connected through a WRS body. The lens adapter obviously works when used with a digital back, which has an FFD much shorter than 20 mm, but in my experience, it will only work for macro photography when used with a mirrorless body.

However, if you're willing to use your EF lenses with preset, fixed apertures (as I do with the Contax N lenses seen in the photos above), you should be able to successfully do so by mounting them on your WRS and adapting its camera mount to accept the Sigma FP L body and position it in the correct location.

In case you're curious, here's a photo of the camera mount setup I fabricated to mount an A7R body on my WDS:



For a few reasons (but mostly because the OEM sliding, spring-loaded clamp would allow the A7R & monitor combo to droop slightly, applying an unwanted rear tilt, due to their weight overpowering the spring pressure), I had to ditch the OEM mounting plate and use this arrangement. On the positive side, IIRC, no permanent modifications wee required to be made to the WDS to implement this camera mounting setup and using the Actus rotating camera mount bracket is much more convenient to use in the field. (Note that I had to fabricate my own camera mount ring from a generic, Chinese-made E-mount reverse ring because the OEM Cambo ring was nearly 1 mm thicker and this prevented the lenses from focusing at infinity.)

Anyway, good luck with your project(s)! :)
 
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