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Cambo Actus Actar Lens Mount
- Thread starter ericstaud
- Start date
Alkibiades
Well-known member
yes, most of them exept the rebuild 35 mm shift lenses ( Laowa, Symyang).
rdeloe
Well-known member
You and I are on the same page Eric. I also use an Arca-Swiss F-Universalis and have wondered whether it would be possible to transfer an Actar-35 (rehoused Contax 35mm) onto a board for my F-Universalis. I've never held an Actar in my hand so take this with a grain of salt, but I have to think they've screwed the lens to the board (simplest, strongest solution) or they're using a locking ring (which seems unnecessarily complicated because a threaded mount would be required, and that's an extra expense).
I've re-housed and remounted lots of lenses for use on my F-Universalis. If you have the mechanical skill, or you have access to a decent machinist, it can be quite straightforward. For example, I removed the shift mechanism on my Leica PC Super-Angulon and put on a new bayonet mount so I can use it on an Arca-Swiss board I built for that mount. I did the same with the Samyang 24mm tilt-shift lens (which I'm quite confident is the one that Cambo uses for their Actar-24). The Mamiya G lenses I use are re-mounted too.
The main reason I didn't try remounting the Actar-35 is that the unmodified lens uses a floating element design to correct poor performance at close distances. There are different ways of doing this, but all of them are changing the spacing between lens elements depending on focus distance. I know from careful testing using my lenses with floating element designs (Pentax-A 645 35/3.5, Leica PC Super-Angulon 28/2.8, Samyang 24/3.5) that optical performance is unacceptable when you bypass the floating element system, which is what Cambo is doing when it rehouses lenses like the Contax 645 35/3.5 and focuses them by rail. For best performance, I have to position these lenses on my F-Universalis at their precise flange distance, and focus using the lens' helicoid.
I've re-housed and remounted lots of lenses for use on my F-Universalis. If you have the mechanical skill, or you have access to a decent machinist, it can be quite straightforward. For example, I removed the shift mechanism on my Leica PC Super-Angulon and put on a new bayonet mount so I can use it on an Arca-Swiss board I built for that mount. I did the same with the Samyang 24mm tilt-shift lens (which I'm quite confident is the one that Cambo uses for their Actar-24). The Mamiya G lenses I use are re-mounted too.
The main reason I didn't try remounting the Actar-35 is that the unmodified lens uses a floating element design to correct poor performance at close distances. There are different ways of doing this, but all of them are changing the spacing between lens elements depending on focus distance. I know from careful testing using my lenses with floating element designs (Pentax-A 645 35/3.5, Leica PC Super-Angulon 28/2.8, Samyang 24/3.5) that optical performance is unacceptable when you bypass the floating element system, which is what Cambo is doing when it rehouses lenses like the Contax 645 35/3.5 and focuses them by rail. For best performance, I have to position these lenses on my F-Universalis at their precise flange distance, and focus using the lens' helicoid.
Thanks, Rob. I'm only using my Arca for occasional product photography, so I'm not highly motivated to adapt a bunch of lenses, but it sounds really interesting. What you're saying about the floating elements makes a lot of sense.
One solution for using Actus on Arca would be to glue the Actus, lens board and all, to an Arca board with a big enough hole ;-)
rdeloe
Well-known member
Many is the lens I've taped to lens boards to try them out!
I prefer putting a mount on a board and then attaching lenses that use that mount to the board, but in some cases it's simpler to just screw the lens to board using the screws and holes that hold the native mount to the lens.
Once you get going on that path, you discover all kinds of short cuts. For example, a lens with an M42 mount can be locked to a Copal 1 lens board. If you don't have an M42 locking ring, an inexpensive M42 to Canon EF adapter makes a handy locking ring. There are a lot of enlarger and industrial lenses that work well as taking lenses and can be "adapted" easily with that simple solution.
I prefer putting a mount on a board and then attaching lenses that use that mount to the board, but in some cases it's simpler to just screw the lens to board using the screws and holes that hold the native mount to the lens.
Once you get going on that path, you discover all kinds of short cuts. For example, a lens with an M42 mount can be locked to a Copal 1 lens board. If you don't have an M42 locking ring, an inexpensive M42 to Canon EF adapter makes a handy locking ring. There are a lot of enlarger and industrial lenses that work well as taking lenses and can be "adapted" easily with that simple solution.
Alkibiades
Well-known member
As I wrote you can remount all these lenses ( exept the 35 mm wide angle rebranded Laowa, Symjang...) and put them on arca swiss lensboards.
But I simply would not do that, why?
becouse you get much better lenses and much cheaper lenses that you can use on your Arca.
When you shoot products so you can get Apo Digarons or Apo Sironar Digital lenses for good prices and they are ways better.
when you want to spend less so go for some analoge lenses, they are also very good.
Really cheap and even better than the actars ( that I simply asian copy of rodenstock-schneider lenses) are older Componon-S lenses.
They are very good when stopped 2 apertures down.
areallygrumpyoldsod
New member
The lens is in 3 parts -- the cambo plate; the front element and the rear element.
The Rear Element unscrews relatively easily.
The front element does not (and I am not willing to force mine) and if one tries the outer shell of the lens rotates before the lens comes unscrewed from the plate.
I doubt Cambo has designed their lense to work easily across systems AND I would recommend you look at how you could fit the cambo plate to your Universalis rather than disassemble the lens.
Attachments
rdeloe
Well-known member
This is incredibly helpful info! Thanks for sharing.
If I'm understanding you correctly, as the fourth picture shows, the plate is attached to the front part of the lens. Do you think it's threaded together, or are you seeing any evidence of screws?
Which lens is that in your pictures?
rdeloe
Well-known member
For people who use medium format backs, your advice makes sense. But Cambo is going after people who are using mirrorless cameras. At the wide end, there are few options. For GFX users, for example, the widest good lens is the Pentax-A 645 35mm f/3.5. None of the wide Rodenstock and Schneider lenses will work. Cambo has been smart to put together some options that make the Actus viable for people using mirrorless cameras. Unfortunately, some of those options are based on lenses that aren't very good in their native format, and from what I can see all of the wide ones they've rehoused were floating element designs, and they've bypassed that design, which weakens their Actars at close distances.
Alkibiades
Well-known member
You are absolutly right, but the guy ask here not for wide angle lenses but lenses for studio- product photography. So lenses from 60 mm-180 mm, where options in the middle are the best for it: 100-120 mm.
rdeloe
Well-known member
We did discover he was interested in product photography eventually. But the thread started out with a broader focus. Anyone reading this later will benefit from the more complete story.
Steve Hendrix
Well-known member
The lack of optimal wide angle lens options is not an issue exclusive to Cambo. Outside of Rodenstock/Schneider view camera lenses, elite level wide angle lenses are virtually non existent for any view camera paired with a mirrorless body. Legacy medium format lenses may have the image circle, but on the wide end, they are at best, barely competent. Newer lens designs require some sort of electronic interface to control the aperture and thus far the only solution has been created for Canon lenses, which have left photographers desiring better quality optics on the wide angle side of things. Fuji is addressing this to some degree with some tilt/shift options that in our short time with seem like they'll easily surpass the quality of the Canon lenses , though these do not fully resolve the view camera conundrum.
It's unfortunate, but I don't see anyone on the optical side solving the issue, because no one is going to be making elite wide angle lenses with manual control of aperture that can achieve infinity focus with mirrorless cameras mounted on a view camera
For the lenses that utilize floating elements, in cases where that design has been altered by Cambo, reasons exist for that, and if the results are not quite as expansively effective as the lens produces in its native state, the lenses still are very usable. I think it might be a good idea for you to contact Cambo and perhaps get some more background on this topic.
Steve Hendrix/CI
areallygrumpyoldsod
New member
No Screws - so it is probably threaded onto the plate. BUT trying to turn the front element just rotates the outer shell and not the inner lens element.
rdeloe
Well-known member
I always appreciate it when you chime in on these topics Steve. Thanks.
A few thoughts on my perspective....
In order to be able to offer wide angle lenses that can be focused by rail, Cambo gave away close focus performance. That's a completely reasonable design decision if most customers are using the lenses at distances where the floating element system doesn't kick in strongly. That probably covers a lot, or even most, of the landscape scale and architectural folks. I would notice a lot more because I'm often at magnifications where the close focus elements will be important, even with wide angle lenses.
A few thoughts on my perspective....
The wide end is tough for people using mirrorless bodies on digital view cameras. I'm grateful that Pentax did as well as it did with the Pentax-A 645 35/3.5. It's a focal length I use a lot, and it performs well. As a general conclusion, we'll have to agree to disagree on "at best, barely competent". At f/8 and f/11, a good copy of the Pentax-A 645 35/3.5 is easily as good as f/8 and f/11 on my GF 35-70 on a GFX 100S sensor. Mind you I'm not an architectural photographer; for those folks, who regularly need a lot more shift than I use, "barely competent" is a fair assessment.
I wish you were wrong, but I don't think you are. In the face of the market, plus computational photography and generative AI, I think that for the most part, we already have the lenses that will exist in this space. Thank goodness Fuji was willing to take a gamble and put out some top notch tilt-shift lenses.
It's like the old gag "(1) Good. (2) Fast. (3) Cheap. Pick two".
In order to be able to offer wide angle lenses that can be focused by rail, Cambo gave away close focus performance. That's a completely reasonable design decision if most customers are using the lenses at distances where the floating element system doesn't kick in strongly. That probably covers a lot, or even most, of the landscape scale and architectural folks. I would notice a lot more because I'm often at magnifications where the close focus elements will be important, even with wide angle lenses.
MGrayson
Subscriber and Workshop Member
There's always the Rodenstock 105mm floating element macro. From 4:1 to 1:4, it is supposedly unsurpassed. (I probably learned about this lens from a link you posted, so I'm fairly sure you're aware of it. This is more for everyone else!)
Matt
Steve Hendrix
Well-known member
Hi Rob - yes, when I say barely competent, I mean that in several ways. One, that being a view camera, the use case would at least commonly involve shifts, perhaps substantial ones. And edge to edge performance is often desired (well, when is it not) or even critical for their use. But also, I have had numerous clients mention the Pentax 35mm and have some who happily use it, but I meant as a genre, overall, the selections for edge to edge shifted performance are mediocre (compared to what could be optimal).
Also, a client purchased a view camera system from me recently and I mentioned that Pentax lens, they purchased it from a used source, and they sent it to me to test with their new system (I offered to do this). The lens was very disappointing at the edges. Un-shifted, it was ok. He decided to return it. Perhaps this wasn't a great copy. But that again points to the challenge of an optimal solution for this category, old, legacy lenses whose performance will be a mystery (could be good, could be bad). There are other lenses in this category that might be somewhere in that performance vicinity (Hasselblad, Mamiya), but I've not seen any real heroes there either (for what photographers really want).
For the Cambo and the lenses they've set the floating element for, they did feel they needed to make a design decision. In my experience, the quandary and intents of manufacturers are often unknown and assumed, often negatively without knowledge or due consideration of the reasons for their decision. As someone who has worked both sides of the aisle (the manufacturer side and the end user side, dealer), I value both perspectives, but often the manufacturer perspective is either unknown or assumed (they don't do a good job of sharing for various reasons, some legitimate). But whenever I do discuss confounding decisions with them, I frequently (but not always!) come away with an understanding that puts the brakes on my impulse to blast them.
Steve Hendrix/CI
rdeloe
Well-known member
Like you, I always try to put appropriate qualifiers around what I say because there are a lot of variables. I would never recommend a Pentax-A 645 35/3.5 to someone who needs edge-to-edge excellent performance. It's not available with that lens, and the moustache distortion is a frustration.
It's an excellent performer for my situation because I use tilt and swing much more than shift. I don't use the lens for flat stitched panoramas, and I don't rely on 10mm shifts. I mostly use shift for composition adjustment and fine tuning, and straight lines are rarely a central feature in what I do.
But sometimes I do need lots of rise along with tilt, and it gets the job done. In this composition, I needed that house to look natural (~10mm of rise fixed that), and I need front-to-back sharpness. The leaves at the top of the tree at left are a tiny bit soft because they're just outside the wedge of acceptable sharpness, but the people who are going to be studying this image at a workshop in a couple days are not going to notice that.
Pentax-A 645 35/3.5 @ f/11 on GFX 100S. 10mm of rise and some tilt with F-Univeralis
Anyone who is buying a Pentax-A lens today is spending money on something that has been knocking around for over three decades. The copy I had before the one I'm using now was very good, I thought, but the one I just bought to replace it is significantly better. So it goes with old, used lenses.
No heroes indeed. But I am forgiving of my humble Pentax's flaws because it doesn't let me done when I need it.
I get that, I really do. It's all about trade-offs, and perfection is the enemy of done. Some people have unrealistic expectations about what can be achieved within reasonable design parameters. I don't. I just wish Cambo would be a bit more forthcoming about their choices. I have tried to engage them about their decisions, but they haven't been very forthcoming. I understand why they might want to be cagey. Personally, I think for the market they are selling into, a bit of customer education would be enough to make people comfortable. But it's their business.
rdeloe
Well-known member
I've never used one of those Matt, but it looks like a killer lens.
It helps that the floating element system is integrated into the Rodenstock 105mm lens. It would have been terrific if Cambo could have built a floating element correction ring into its re-housed lenses, but I seriously doubt that's possible because the donor lenses didn't have such a ring it in the first place, and each of the ones they're using as donor lenses likely does the "floating" part differently.
For instance, on my Pentax-A 645 35/3.5, the "floating" system is very simple: the lens is comprised of two groups that screw into the internal mount. The helicoid simply changes the spacing between them. In contrast, on my Leica PC Super-Angulon 28/2.8, the spacing between the front of the front group and the rear of the rear group doesn't change as you focus from infinity to minimum focus distance. I'd have to take it apart completely to be sure, but it looks like there's a third group in between them that is moving around as you focus. Clever optical designers have found lots of ways to do this it seems.
Thanks very much for those photos. Very helpful.
It's an interesting twist to have a set of view camera lenses that can only be used on one model of view camera. Part of the beauty of a view camera is that any lens from any manufacturer can be used. I assume Cambo's choice might drive some customers toward the Actus for the wider range of lens choices.