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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

New 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

New 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.
 

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