XCD 21mm for architecture instead of tech cam

[rdeloe]

Hi there, this is the exact dilemma I face, but I fear with far less knowledge than the people posting here. I have a Cambo actus db2 with 50cv11 back. What is the best option to obtain the widest angle for architecture? Currently I use the 40mm CF fle hass v lense. I require wider and more room to correct with movements. My head hurts with trying to understand the large format lenses, and do I need a center filter with these options. Any help / advice on what I should be looking at would be awesome appreciated!!

With that setup you should have access to wider lens choices than what you're using. Have you asked Cambo? I believe they publish lists of compatible lenses.

The "best option" may not fit within your budget. Other people will be able to help more if you can give a sense for what you're willing to spend.

With no knowledge of your budget, here are some ideas:

• A relatively inexpensive, and very wide (compared to what you have now) option is the Laowa 20mm shift lens. It comes in various mounts. You don't need the lens' shift mechanism because you can do the movements with your Actus. I have received positive reports about this lens, but I don't know about distortion (how much, what form it takes).
• I'm using a Leica PC Super-Angulon 28/2.8 at the moment (same lens as Schneider Kreuznach PC Super-Angulon 28/2.8, and same optics -- minus close focusing element -- as Schneider-Kreuznach Digitar 28/2.8). I would not recommend it for you. There's not enough shift room on your sensor for it to be a good choice for architecture. I use it because I don't need a lot of shift; I got it for tilt and swing, with some room for very small shifts (a few mm). You can forget about the other film-era 28mm shift lenses (PC-Nikkor 28/3.5 and Pentax K 28/3.5). They are simply not good enough.
• Cambo sells some lenses under its own brand, including an Actar-24. I haven't heard stellar reports about it. My hunch is that it's a re-housed Samyang 24mm f/3.5 t-s lens, but I've never heard one way or the other. If it is a rehoused Samyang, I'd be worried about the fact that the Samyang on its native mount has a close focusing element, which Cambo appears to be ignoring. It's also not a great lens. I get by with my copy, but only because I don't use it a lot, and I don't generally have to worry about the distortion. You do.
• A slightly wider lens than your Hasselblad 40mm is the Pentax 645 35mm (A or D-FA, but not FA). I think it's superb, but I don't have to deal with the moustache distortion that you would have to sort out. Plus it's not much wider than what you have.
• Cambo sells a Canon EF adapter that would let you use the Canon 24mm f/3.5 TS-E II. People are making a living with that one, and you might even consider it affordable. I don't really see the point of putting one of these on an Actus though because it has the movements you need built in.
• There are wider technical camera lenses from Schneider-Kreuznach and Rodenstock, but now we're talking money. You'd also need to be sure that the flange distance and rear lens cell were compatible with your setup. Cambo should be able to tell you immediately.

Good luck with your hunt. Hopefully someone who uses an outfit like yours for architecture will respond.

 

[strohscw]

I wish Hasselblad would implement Leica's Perspective Correction where we can see in Live View the frame of the corrected image. That would simplify the framing.

I can only agree with that, especially with the X2D where I have more pixels than I need this would be a great addition. I never thought I would like the Leica M's perspective correction so much.

 

[Robert Salisbury]

With that setup you should have access to wider lens choices than what you're using. Have you asked Cambo? I believe they publish lists of compatible lenses.

The "best option" may not fit within your budget. Other people will be able to help more if you can give a sense for what you're willing to spend.

With no knowledge of your budget, here are some ideas:

• A relatively inexpensive, and very wide (compared to what you have now) option is the Laowa 20mm shift lens. It comes in various mounts. You don't need the lens' shift mechanism because you can do the movements with your Actus. I have received positive reports about this lens, but I don't know about distortion (how much, what form it takes).
• I'm using a Leica PC Super-Angulon 28/2.8 at the moment (same lens as Schneider Kreuznach PC Super-Angulon 28/2.8, and same optics -- minus close focusing element -- as Schneider-Kreuznach Digitar 28/2.8). I would not recommend it for you. There's not enough shift room on your sensor for it to be a good choice for architecture. I use it because I don't need a lot of shift; I got it for tilt and swing, with some room for very small shifts (a few mm). You can forget about the other film-era 28mm shift lenses (PC-Nikkor 28/3.5 and Pentax K 28/3.5). They are simply not good enough.
• Cambo sells some lenses under its own brand, including an Actar-24. I haven't heard stellar reports about it. My hunch is that it's a re-housed Samyang 24mm f/3.5 t-s lens, but I've never heard one way or the other. If it is a rehoused Samyang, I'd be worried about the fact that the Samyang on its native mount has a close focusing element, which Cambo appears to be ignoring. It's also not a great lens. I get by with my copy, but only because I don't use it a lot, and I don't generally have to worry about the distortion. You do.
• A slightly wider lens than your Hasselblad 40mm is the Pentax 645 35mm (A or D-FA, but not FA). I think it's superb, but I don't have to deal with the moustache distortion that you would have to sort out. Plus it's not much wider than what you have.
• Cambo sells a Canon EF adapter that would let you use the Canon 24mm f/3.5 TS-E II. People are making a living with that one, and you might even consider it affordable. I don't really see the point of putting one of these on an Actus though because it has the movements you need built in.
• There are wider technical camera lenses from Schneider-Kreuznach and Rodenstock, but now we're talking money. You'd also need to be sure that the flange distance and rear lens cell were compatible with your setup. Cambo should be able to tell you immediately.

Good luck with your hunt. Hopefully someone who uses an outfit like yours for architecture will respond.

Thank you so much for taking the time to reply. My budget is about 3k GBP as thats what a new 21mm is. Begrugingly though!!
I have the 645 D-fa, and I have just found out that the image circle actually covers there 645 film cameras, which I presume would be an image circle of at least 56mm? Stick with me on this as i find this whole medium format sizing confusing, as there are so many sizes in this range. i presummed as it was a digital lense then it weas just for the 645d and z cropped sensors. Would that actually give me a wider field of view than the 40mm hass? If that has a circle of 80mm, don't I have more room to shift and stitch, than say the 56 maybe 60mm ( can't actually find the specific size yet) of the 35mm? I used to have the 24mm pentax, and now wonder if selling that was not such a clever idea. But I think the possibilitys of movements was limited, from what I got told when purchasing the DB2.
I have contacted Cambo, and with a speedy reply they have said, the Rodenstoch Digaron 23 is the widest I can get. I dont have the availably body parts to pay for that!
They have mentioned the 15mm and 19mm Actar, but I am waiting on confirmation of the movements available for my sensor.
When I first started on this journey I was given a list of possible affordable options to look out for
35mm Apo Grandagon

35mm Apo Digitar.

Schneider 38mm Super Angulon XL

47mm Super Angulon XL

47mm Apo Digitar

45mm Apo Grandagon

45mm Apo Sironar Digital

I have found a 35mm Apo Digitar and also a Rodenstock APO Sironar 35mm , any thoughts for my situation?

Thanks again to all that help

Robert

 

[TimoK]

List of Actus compatible lenses is published at Capture Integration site https://www.captureintegration.com/cambo-actus-lens-compatibility-table/
The Schneider lenses are missing maybe because their production is discontinued. And I don't understand why they list Rody 35mm lenses as not compatible.
But still much information.

 

[MGrayson]

I can only agree with that, especially with the X2D where I have more pixels than I need this would be a great addition. I never thought I would like the Leica M's perspective correction so much.

As long as the image has enough "vertical" lines, then it's not hard to anticipate what will be in the final image. The key is deciding where the bottom of your crop will be. The inward slanting "verticals" from the intersection of that base with the sides of the frame will be the edges of the corrected image. I haven't used the M version, but if it always assumes that you are using the entire height of the image, it will trim the sides more than necessary.

The 21mm is a very wide lens, and you may not need to tilt it up so much in order to get the top of your desired image. That way you get more of the sides and suffer less stretching of the detail at the top.

Introduction to Projective Geometry

Where do the formulas for converging lines when tilting the camera come from? There is an amazingly simple trick to handle all projective transformations without remembering a bunch of matrices. Let's let x and y be our usual coordinates and let z be the direction straight ahead. Then the vertical sides of a building might be the lines x=1 and x=-1, and the top and bottoms of the building are y=4 and y=0. The key to projective geometry is to homogenize. In mathematics, that means giving every term the same total power of variables. An equation like x=1 has one power on the left and zero on the right, so we replace the "1" by "z". The equation now is x=z, and we recover our original line by setting z=1.

To show the power of this, let's look straight up. The equation is STILL x=z, but now we're looking in the y direction, and setting y=1 (that's our new projection screen) leaves the equation unchanged. in the x,z plane, x=z is a diagonal line. All the vertical lines x = a become x = a*z, which are lines of different slope all passing through the origin. They are converging to the vanishing point! And that's what you see when you look straight up when surrounded by tall buildings.

So what happens if we tilt a little bit. Instead of projecting onto the plane z=1 (straight forward) or y=1 (straight up), we may be projecting onto a slightly inclined plane (tilt it up at an angle "ø"). Ok, the math gets messier, as our image plane is now z*Cos(ø) + y*Sin(ø) = 1. Substitute in the side of our building x=z and get (after simplifying) y = Csc(ø) - x*Cot(ø). This is a line with large positive intercept and large negative slope, which is exactly what a slightly slanted side of a building SHOULD be. Ok, real numbers. Slant up by ø = 5 degrees and you get y = 11.47 - 11.43*x. The vanishing point is high up and the slope is large in order to converge to that high point.

Now! Suppose I want to crop to the base of the building where y=0. This spreading of the base is the source of truncated sides as we tilt up more. In fact, the base of the building is at, well, plug in y=0 above, and get x = Sec(ø), This starts at 1 when ø=0, is 1.414 when ø = 45 degrees, is 2 when ø = 60 degrees, and is infinite when ø=90 degrees. The more tilt, the wider the base of the building and the less of the horizontal baseline you keep in the image.

Enough for now.

*Homogenizing more complicated expressions. Something like x^2 = y^3 + y + 1 would become z*x^2 = y^3 + y*z^2 + z^3. Now the power of every term is three. Multiplying all the coordinates by, say, 5, keeps the equation true - that's what it means to be homogeneous. In fact, that's why it's called Projective Geometry - because a thing that is true somewhere is true on the entire line (projection) through the origin. Lines are its basic objects.

 

[guphotography]

How much movement does your camera allow?

Use this visualiser, you can work out which lens and back combination would work for you.

DT Visualizer - Image Circle

I had three copies of Pentex 645 D FA 35mm, one was very sharp, but I dreaded the distortion with movements, that was when I first started with medium format sensor (50R), gone through a fair amount of ordeal and gone over to tech cam 8 months later.

I know another shooter works with actus db with phase one iq250 back and a collection rodenstock lenses, most actus users I know tend to work with either gfx 50r or smaller mirrorless sensors.

 

[Thorkil]

Dear Fellows
Any experience with a Loawa 20mm f4 zero D shift on a X1D, and which mount to go for (GFX?) and which adapter?
Or just stay with a XCD 21/4? and do it in pp.
KR Thorkil

 

[rdeloe]

Thank you so much for taking the time to reply. My budget is about 3k GBP as thats what a new 21mm is. Begrugingly though!!

I have the 645 D-fa, and I have just found out that the image circle actually covers there 645 film cameras, which I presume would be an image circle of at least 56mm? Stick with me on this as i find this whole medium format sizing confusing, as there are so many sizes in this range. i presummed as it was a digital lense then it weas just for the 645d and z cropped sensors. Would that actually give me a wider field of view than the 40mm hass? If that has a circle of 80mm, don't I have more room to shift and stitch, than say the 56 maybe 60mm ( can't actually find the specific size yet) of the 35mm? I used to have the 24mm pentax, and now wonder if selling that was not such a clever idea. But I think the possibilitys of movements was limited, from what I got told when purchasing the DB2.

Which 645 D-FA do you have? Is it the 25mm? That one covers 645 film. The 645 DA has a narrower hood that mechanically vignettes, so it only covers 33mm x 44mm.

The way this works is the lens designers for medium format lenses design the lens with an image circle that covers the "sensor" (be it film or digital). Depending on the design, the circle of decent image quality that covers the sensor may be tight to the format, or a bit bigger. To cover a 33mm x 44mm circle (GFX, Pentax-D or Z, your Hassy) you need a 55mm IC. This is based on the diagonal of the sensor, so the square root of (33^2 + 44^2). To cover 645 film, you need around 71mm. It's "around" because an image on 645 film is not actually 60mm x 45mm -- more like 57mm x 42mm. So... if you have a 645 lens, you have room to shift around 10mm on the long edge (e.g., in portrait orientation, you could rise 10mm; in landscape you could shift 10mm). It might be more depending on the lens. Your Hasselblad lens for 6x6 film should have an image circle of around 79mm.

I can't tell from your message which one you have, but if it's the 25mm D-FA, as long as you can control the aperture, you could use it on your Cambo. Maybe. I say "maybe" because it's big and heavy and may pull the front standard down a bit. You would need to put it at the Pentax 645 flange distance on your rail, and then focus via the lens but shift/tilt via the Actus.

I have contacted Cambo, and with a speedy reply they have said, the Rodenstoch Digaron 23 is the widest I can get. I dont have the availably body parts to pay for that!
They have mentioned the 15mm and 19mm Actar, but I am waiting on confirmation of the movements available for my sensor.

That Rodenstock is much more than your budget. There are definitely cheaper options.

The 15mm "Actar" appears to be a re-housed Laowa Zero-D Shift 15mm lens. I've heard reports that it's not very good, but their 20mm is supposed to be much better. I have no personal experience on these. The Actar-19 is a re-housed Nikon 19mm shift lens. If you want that one, research how the Nikon version does on GFX.

You'll see the trend here: Cambo does not make any lenses. They use existing lenses and re-house them. It's a good strategy, except I have serious concerns about image quality when you use the optics from a lens that has close focusing elements, but you don't use those close focusing elements. This covers most if not all of the modern wide angle retrofocus lens designs.

When I first started on this journey I was given a list of possible affordable options to look out for
35mm Apo Grandagon

35mm Apo Digitar.

Schneider 38mm Super Angulon XL

47mm Super Angulon XL

47mm Apo Digitar

45mm Apo Grandagon

45mm Apo Sironar Digital

I have found a 35mm Apo Digitar and also a Rodenstock APO Sironar 35mm , any thoughts for my situation?

These are all older lens designs, some designed for film. That doesn't mean they won't work OK, or even well. Some don't play nice with some digital sensors. For example, I tried a Rodenstock APO-Grandagon 55mm on my Fuji GFX 50R and it had horrendous lens cast on the smallest shift. The sensor on the 100S is somewhat less prone to that because it's "Back Side Illuminted" (BSI). I don't know about your Hassy.

Personally, given that you have a 40mm lens you seem to be happy with, I wouldn't spend any money on any of the ones you listed here.

What's not clear to me is how much wider than 40mm you want. For example, that 20mm Laowa is a radically different lens. You might find 20mm to be too wide. For comparison to full frame, on the long edge, a 20mm lens on your Hassy is like a 16.4mm on full frame. If you came from 4x5 film, a 20mm lens on a 33mm x 44mm sensor is like a 56.3mm lens on 4x4 (long edge). I find that for the way I photograph, 24mm on a 33mm x 44mm sensor is too wide most of the time. I do most of my "wide" work with 35mm. But plenty of people can't have wide enough.

Thanks again to all that help

Robert

My pleasure Robert.
Rob

 

[Robert Salisbury]

"Which 645 D-FA do you have? Is it the 25mm? That one covers 645 film. The 645 DA has a narrower hood that mechanically vignettes, so it only covers 33mm x 44mm."
Sorry its the 35mm I still have. I did have the 25mm but sold that. I am now in the process of selling all my 645 gear to fund this new lens.

" I can't tell from your message which one you have, but if it's the 25mm D-FA, as long as you can control the aperture, you could use it on your Cambo "
Yep this rings a bell, apature is controlled via camera body , so it was no good and not an option. The Actus was a "lockdown purchase" a couple of years ago. I remember various conversations with the shop I purchased from going over that particular problem. I was shooting with the Pentax 645z and seeing the cambo had a pentax mount mde me intially think I could turn all my lenses into tilt shifts! I originaly shot film many years ago hence the hassy stuff, when the 50cv came out I thought I could constrict my kit abit but still shoot film and digital through the one camera. . I think all the months of lockdown and overthinking everything has clouded my vision.

" What's not clear to me is how much wider than 40mm you want"
I think my idea is something close to the canon 17mm t&s Once upon atime I had the 24mm on a canon 1dx loved it!, but just not quite wide enough to have a go at the architecture I wanted to shoot. For landscapes I never go wider than 24mm on full frame , the 40mm in the 6x6 is mostly too wide for my landscapes so I generally stick to the 50mm and 80mm. Shooting in cites I find my camera is always up against the oppsoite wall and just can't get things in. I like space in my images if I can get it.

I seem to be struggling so much with this, I'm not very accademic or technically minded and some of the above ( although very gratefull) is blowing my mind. ideally I wish i could find a shop here in the UK that has several options, I can go , take the actus and put a few on , stand in the street an go" ill have that one please" as i can see exactly what i am going to get.
Just before lockdown I went to Venice, my first time. I was shooting with the 645z and even with the 25mm I had then I was struggling and thats not even talking about the lack of correction. Thats what satrted me on the path of technical cameras and movements. This image bellow taken by Rohan Reilly I believe is taken with the 17mm on a sony and probably stiched. From this position I couldn't even get the whole building in never mind canals or the fact it looks fairly correct in perspective. The ability to have something close to this would be great, if its too wide i'll walk closer or put a longer hassy lens on. Or am i complety barking up the wrong tree? cheers again though,its appreciated.

 

[Robert Salisbury]

How much movement does your camera allow?

Use this visualiser, you can work out which lens and back combination would work for you.

DT Visualizer - Image Circle

I had three copies of Pentex 645 D FA 35mm, one was very sharp, but I dreaded the distortion with movements, that was when I first started with medium format sensor (50R), gone through a fair amount of ordeal and gone over to tech cam 8 months later.

I know another shooter works with actus db with phase one iq250 back and a collection rodenstock lenses, most actus users I know tend to work with either gfx 50r or smaller mirrorless sensors.

The camera allows 20mm +/- shift and 15mm +/- rise

Thanks for the link, appreciated. From what i understand with my sensor the the 32mmRodenstock gives my the best option for angle of view V amount of movement. I am basing that on image circle size enabling me to have more correction available if neededand also giving the overall wider field of view if moved to cameras limits. Is that correct? The 23mm is wider obviously but with the much less image circle , the movement is much more limited? The 35 don't seem to give me any advantage over the 40mm hassy I have. That can move about 12mm shift and 10mm rise which is more than the 35, so would equall roughly the same field of view. Or am I completly missunderstanding something?

 

[rdeloe]

"Which 645 D-FA do you have? Is it the 25mm? That one covers 645 film. The 645 DA has a narrower hood that mechanically vignettes, so it only covers 33mm x 44mm."
Sorry its the 35mm I still have. I did have the 25mm but sold that. I am now in the process of selling all my 645 gear to fund this new lens.

" I can't tell from your message which one you have, but if it's the 25mm D-FA, as long as you can control the aperture, you could use it on your Cambo "
Yep this rings a bell, apature is controlled via camera body , so it was no good and not an option. The Actus was a "lockdown purchase" a couple of years ago. I remember various conversations with the shop I purchased from going over that particular problem. I was shooting with the Pentax 645z and seeing the cambo had a pentax mount mde me intially think I could turn all my lenses into tilt shifts! I originaly shot film many years ago hence the hassy stuff, when the 50cv came out I thought I could constrict my kit abit but still shoot film and digital through the one camera. . I think all the months of lockdown and overthinking everything has clouded my vision.

" What's not clear to me is how much wider than 40mm you want"
I think my idea is something close to the canon 17mm t&s Once upon atime I had the 24mm on a canon 1dx loved it!, but just not quite wide enough to have a go at the architecture I wanted to shoot. For landscapes I never go wider than 24mm on full frame , the 40mm in the 6x6 is mostly too wide for my landscapes so I generally stick to the 50mm and 80mm. Shooting in cites I find my camera is always up against the oppsoite wall and just can't get things in. I like space in my images if I can get it.

I seem to be struggling so much with this, I'm not very accademic or technically minded and some of the above ( although very gratefull) is blowing my mind. ideally I wish i could find a shop here in the UK that has several options, I can go , take the actus and put a few on , stand in the street an go" ill have that one please" as i can see exactly what i am going to get.
Just before lockdown I went to Venice, my first time. I was shooting with the 645z and even with the 25mm I had then I was struggling and thats not even talking about the lack of correction. Thats what satrted me on the path of technical cameras and movements. This image bellow taken by Rohan Reilly I believe is taken with the 17mm on a sony and probably stiched. From this position I couldn't even get the whole building in never mind canals or the fact it looks fairly correct in perspective. The ability to have something close to this would be great, if its too wide i'll walk closer or put a longer hassy lens on. Or am i complety barking up the wrong tree? cheers again though,its appreciated.
View attachment 197929

That helps clear things up a lot.

If what you're after is the angle of view of a Canon 17mm lens on full frame, then the lens you want to look at is the Laowa 20mm f/4 Zero-D Shift from Venus Optics. It will have roughly the same angle on a 33mm x 44mm sensor as the 17mm does on full frame (assuming we're comparing the long side of the frame. If we're comparing the short side of the frame, then the roughly equivalent angle of view will be 23-24mm.

Laowa 20mm f/4 Zero-D Shift - Laowa Lens

Laowa 20mm f/4 Zero-D Shift is an ultra-wide-angle shift lens that you cannot resist. On top of the high image sharpness and nearly no distortion (Zero-D), the lens also comes with a rotatable lens hood for avoiding flares and protecting the front lens element.

www.laowalenses.ca

Here's a thread over at DPReview about the lens on GFX. I posted a link to Keith Cooper's review of the lens on Canon in this thread. https://www.dpreview.com/forums/thread/4667866#forum-post-66431176

These lenses come in all kinds of different mounts. That's where things get a bit tricky.

• If you are not willing to remount the lens, you need to pick a native mount that will work on your Actus and allow for the correct flange distance with your Hasselblad back.
• If you are willing to to disassemble and remount (which might be simple if you're good at this kind of thing), then using it will be straightforward because removing the shift mechanism will buy you loads of flange distance.

The only other consideration is whether the image circle is large enough for your purposes. You get 8mm of shift room on a 33m x 44mm sensor according to Laowa.

Cheers,
Rob

 

[rdeloe]

The camera allows 20mm +/- shift and 15mm +/- rise

Thanks for the link, appreciated. From what i understand with my sensor the the 32mmRodenstock gives my the best option for angle of view V amount of movement. I am basing that on image circle size enabling me to have more correction available if neededand also giving the overall wider field of view if moved to cameras limits. Is that correct? The 23mm is wider obviously but with the much less image circle , the movement is much more limited? The 35 don't seem to give me any advantage over the 40mm hassy I have. That can move about 12mm shift and 10mm rise which is more than the 35, so would equall roughly the same field of view. Or am I completly missunderstanding something?

One thought on how much shift room you "need"... People shooting Canon shift lenses on full frame are getting 12mm of shift. That means 1/3rd the long edge(12/36). To get the equivalent amount of shift on a 33mm x 44mm sensor, you need 15mm on the long edge or (15/44).

So right there you can see the problem with using a shift lens meant for full frame... The Canon 17mm only allows 12mm of shift regardless of sensor, meaning you can't have the same relative amount of shift as you can on full frame before you hit the edge of the sensor. This is why people in Fuji land are so excited for the forthcoming 30mm tilt-shift lens: it offers 15mm of shift, making it equivalent to the full frame options in terms of movement on the sensor.

 

[Robert Salisbury]

Thanks Rob,

If you are willing to to disassemble and remount (which might be simple if you're good at this kind of thing), then using it will be straightforward because removing the shift mechanism will buy you loads of flange distance.

Do you mean remove the tube before the rear lens elements and then mount , for example a "V" lens mount to the lens?

If you are not willing to remount the lens, you need to pick a native mount that will work on your Actus and allow for the correct flange distance with your Hasselblad back.

such as this https://www.linhofstudio.com/produc...ambo_Canon_EOS_Manual_Front_Lens_Plate_ACB-CM then order the canon version lens?

 

[rdeloe]

Thanks Rob,

Do you mean remove the tube before the rear lens elements and then mount , for example a "V" lens mount to the lens?
such as this https://www.linhofstudio.com/produc...ambo_Canon_EOS_Manual_Front_Lens_Plate_ACB-CM then order the canon version lens?

Shift lenses that don't involve electronics usually have a simple shift (or tilt-shift) mechanism attached to the rest of the lens. Sometimes you can remove the shift mechanism and just attach another mount. Here for example is what I did with the Samyang 24mm f/3.5 tilt-shift lens so I could use it on my MAB Camera (think homemade Actus). I did the same thing with the Lecia PC Super-Angulon 28/3.5 that I also use. I adapt my lenses to Olympus OM mount (long story why that one). As a result, I used that lens on my Toyo VX23D with an OM-mount board, am using it on my MAB Camera, and will use it on a future Arca-Swiss F-Universalis.



You might be able to do something like this with the Laowa lens. Generally what they're doing when it's available in multiple mounts is using a common front half, and bolting on the shift mechanism and mount for each mount system (to get to the correct flange distance).

There inevitably will be problems to solve in a project like this, e.g., how do you hold down the aperture ring and allow it to turn properly? Therefore, it's definitely easier to use the native mount without taking the lens apart -- if it fits and allows enough room for movements.

The Canon EF Actus lens mount you linked should work. There are no electronics, so it can't control a native Canon EF lens. However, there are no electronics on that Laowa lens, so that's not an issue. Given that Cambo sells that part, I have to think that they expect you can put a Canon EF lens on the camera and focus to infinity... I don't know because I don't use an Actus.

One other thought on re-mounting if you go that route: Cambo sells a plane Copal plate. If I used an Actus and liked the Laowa and decided I wanted to remount it, I would attach it directly to one of those Copal plates (or whatever other Cambo plate would fit). If you look at the top-left picture above, I attached a custom M42x1 adapter I had laying around. The idea would be exactly the same using a Cambo plate.