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Thread: Cambo Actus Mini for Pentax 645

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    Cambo Actus Mini for Pentax 645

    Best I can tell, there is a Cambo Actus Mini for (35mm) full-frame digital and a Cambo Actus DB for MF digital backs, but no Cambo Actus for a Pentax 645. Inasmuch as Pentax can't keep the 645Z on the shelves, and inasmuch as movements are not possible on a Pentax 645 (save for one relatively expensive after-market lens), I would have thought that Cambo would fill this gap. B&H sells a new Pentax 645D for about $3,800. That's a price point even a hobbyist such as myself could consider, but if I'm going to switch from 4x5 film to MF digital I'm going to want an opportunity to learn movements on the new camera. Too bad.

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    Subscriber & Workshop Member GrahamWelland's Avatar
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    Re: Cambo Actus Mini for Pentax 645

    The problem is with the mirror box and distance from the lens rear elements to the sensor to achieve infinity focus. Whilst I'm sure that it's possible to mount the Pentax, the best case would be that you'd be limited to longer lenses.
    Remember: adventure before dementia!

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    Re: Cambo Actus Mini for Pentax 645

    Quote Originally Posted by GrahamWelland View Post
    The problem is with the mirror box and distance from the lens rear elements to the sensor to achieve infinity focus. Whilst I'm sure that it's possible to mount the Pentax, the best case would be that you'd be limited to longer lenses.
    Agreed. The worst factor to limit the choice of wide angle lenses for the Pentax system is indeed the flange focal distance.

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    Re: Cambo Actus Mini for Pentax 645

    Quote Originally Posted by GrahamWelland View Post
    The problem is with the mirror box and distance from the lens rear elements to the sensor to achieve infinity focus. Whilst I'm sure that it's possible to mount the Pentax, the best case would be that you'd be limited to longer lenses.
    Yes, of course, I feel foolish. Funny, I haven't used a camera with a mirror in so long I've forgotten they exist.

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    Re: Cambo Actus Mini for Pentax 645

    Quote Originally Posted by GrahamWelland View Post
    The problem is with the mirror box and distance from the lens rear elements to the sensor to achieve infinity focus. Whilst I'm sure that it's possible to mount the Pentax, the best case would be that you'd be limited to longer lenses.
    Right, and I take it that the reason Cambo lists its Pentax 645 lens plate as an accessory for the Actus Mini but not the Actus DB is that those lenses typically don't have a large enough image circle for movements on a MF back. Do I have that right? If so, there seems no affordable way to get wide-angle movements on a MF digital back because not only will a used MF back cost upwards of $5,000, so would a lens (unless a Rodenstock truck happens to break down in front of my house and abandon its cargo). Maybe a Pentax 645D ($4,000) and a Hartblei tilt-shift ($3,000), but even that's a lot of money for not quite the experience I was hoping to get. Too bad, but, as they say, a first-world problem.

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    Re: Cambo Actus Mini for Pentax 645

    Quote Originally Posted by Lobalobo View Post
    Too bad, but, as they say, a first-world problem.
    If you can forget the Sony A7R II is a 35mm camera and view it simply as a digital sensor then you can have a Actus view camera with just about any lens out there attached. Without good live view, (which the Pentax 645D does not have) I imagine the experience on a view camera would be terribly tiresome. In contrast, the Sony has it all with bells on. Short of spending on the new CMOS digital backs I'd stear clear of a view camera unless it has an A7 attached.

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    Re: Cambo Actus Mini for Pentax 645

    Quote Originally Posted by gazwas View Post
    If you can forget the Sony A7R II is a 35mm camera and view it simply as a digital sensor then you can have a Actus view camera with just about any lens out there attached. Without good live view, (which the Pentax 645D does not have) I imagine the experience on a view camera would be terribly tiresome. In contrast, the Sony has it all with bells on. Short of spending on the new CMOS digital backs I'd steer clear of a view camera unless it has an A7 attached.
    Well, the 645D has a mirror for composition so there would be no need to rely on live view, but the Hartblei isn't a view camera, that's true. In any case, on the Sony, You must be right, of course, as the A7R II is why Cambo put out the Actus mini, I take it. Worth considering. Thanks.

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    Re: Cambo Actus Mini for Pentax 645

    Quote Originally Posted by Lobalobo View Post
    Well, the 645D has a mirror for composition so there would be no need to rely on live view.......
    I wasn't thinking for composition although composing on an LCD screen is more like the traditional LF way rather than using a viewfinder but was thinking for critical focusing. While its totally possible to get perfect focus without live view the whole focusing through a view finder then checking 100% image previews on the LCD screen, I feel it is tiresome and not exactly the LF experience you are used to.

    A7 is defiantly worth considering as quite a few in these forums used an A7 with Actus or Universalis very successfully.

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    Subscriber & Workshop Member GrahamWelland's Avatar
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    Re: Cambo Actus Mini for Pentax 645

    I had the Actus & Sony A7R II combination and in fact today I use the Actus DB+ with IQ150 myself as my 'technical' camera.

    The mirrorless A7 body and superb live view / focus peaking worked extremely well with the Actus to make use of movements super easy even on the LCD or EVF. With the rotating back on the standard Actus it was simple also to stitch a couple of frames in either landscape or portrait mode to overcome the 3:2 sensor ratio to get something more akin to 5:4. That also overcame the need for the wider lenses too.

    If you want a cost effective entry into using the Actus and medium format lenses then using the Hasselblad V, Mamiya RZ/645Pro or Pentax mounts allows you to use great manual lenses such as the 40CFE etc with movements. In addition I was able also to mount some of my large format lenses on the Copal 0/1 boards too such as my SA 58 & 72. With the range of lens mounts available including for 35mm lenses you really have an extremely versatile camera platform if movements are your goal and a digital experience similar to using your large format camera (albeit not the inverted composition on the LCD).
    Remember: adventure before dementia!

    As Oscar Wilde said, "my tastes are simple, I only like the best"

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    Re: Cambo Actus Mini for Pentax 645

    Quote Originally Posted by GrahamWelland View Post
    I had the Actus & Sony A7R II combination and in fact today I use the Actus DB+ with IQ150 myself as my 'technical' camera.

    If you want a cost effective entry into using the Actus and medium format lenses then using the Hasselblad V, Mamiya RZ/645Pro or Pentax mounts allows you to use great manual lenses such as the 40CFE etc with movements. In addition I was able also to mount some of my large format lenses on the Copal 0/1 boards too such as my SA 58 & 72. With the range of lens mounts available including for 35mm lenses you really have an extremely versatile camera platform if movements are your goal and a digital experience similar to using your large format camera (albeit not the inverted composition on the LCD).
    Thanks. Is the suggestion that (at least some of) the V, RZ, and Pentax 645 lenses can be mounted to the DB system and a MF back, or were you still talking about using the Actus & Sony A7R II? In any case, thanks for the response.

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    Re: Cambo Actus Mini for Pentax 645

    I think Graham is refering to the A7 however you can still use the same lenses with a MFD back in the same way, however your milage may vary due to their image circle size on the larger MF chip (especially for movements) and the resolving power at the periphery of the image circle. Obviously no such issues on the smaller Sony chip unless with very large movements.

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    Re: Cambo Actus Mini for Pentax 645

    You typically can only use the medium format lenses with the 35mm system such as A7R II or other cameras since all shutter/electronic capture is managed by the body, not the lens.

    You need a flash sync & shutter/release in the lens to trigger a MF back.
    Remember: adventure before dementia!

    As Oscar Wilde said, "my tastes are simple, I only like the best"

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    Re: Cambo Actus Mini for Pentax 645

    Quote Originally Posted by gazwas View Post
    I think Graham is refering to the A7 however you can still use the same lenses with a MFD back in the same way, however your milage may vary due to their image circle size on the larger MF chip (especially for movements) and the resolving power at the periphery of the image circle. Obviously no such issues on the smaller Sony chip unless with very large movements.
    Makes sense, but I wanted to be sure I understood Graham's point and that I was not missing something. Thanks.

    - - - Updated - - -

    Quote Originally Posted by GrahamWelland View Post
    You typically can only use the medium format lenses with the 35mm system such as A7R II or other cameras since all shutter/electronic capture is managed by the body, not the lens.

    You need a flash sync & shutter/release in the lens to trigger a MF back.
    Thanks.

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    Re: Cambo Actus Mini for Pentax 645

    Please, correct me if I am wrong...


    1) Mamiya RZ lenses' register distance (or flange distance) is 105mm.

    2) Pentax 645D/Z's register distance is 70.87mm.

    3) Actus system has a lensplate for Mamiya RZ/RB lens.


    So, if one finds a way of mounting a Pentax 645D/Z camera on a rear standard of an Actus camera, say Actus DB, say using an adapter shaped as a rearplate for a digital back but with a Pentax 645 lensmount on it, then, in theory, one would be able to achieve an infinity focus with any Mamiya RZ/RB lens and still have some space for movements like shift and tilt.
    Uladzimir

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    Senior Member Steve Hendrix's Avatar
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    Re: Cambo Actus Mini for Pentax 645

    The flange distance isn't the only (nor even the primary) factor that negates a Cambo Actus/Pentax 645D-Z combo. The dimensions of the camera body itself will not fit on either Cambo Actus Mini or Actus DB, and if Cambo did produce an Actus just for the Pentax, then it would be a much larger view camera, which somewhat defeats the point of the Actus.

    However, there is a Cambo product that has precedence for this line of thought, and that is the Cambo X2 Pro.

    https://captureintegration.com/cambo/cambo-x-2-pro/

    Interestingly, once the Actus began shipping, I had some clients who liked the concept, but wanted to use medium format digital backs, and not just with Schneider/Rodenstocks. Since the Actus DB only has room for a digital back to mount and rotate/operate (meaning no room for a camera body), the requirement is a lens with a manual shutter mechanism, which rules out medium format lenses.

    However, the X2 Pro does allow mounting the Mamiya/Phase One AFD/DF camera bodies, and then you have a camera body to use as a shutter, which enables Hasselblad V lenses, Mamiya RZ, and so on. Perhaps an interface for Pentax 645 could be produced for the X2 Pro, or perhaps there is some future product that could utilize a medium format camera body like the X2 Pro does with the Mamiya/Phase One bodies. It's all about the level of demand.


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    Re: Cambo Actus Mini for Pentax 645

    My Actus DB+ replaced my Alpa as my primary 'technical' camera but the MF lenses only worked for me on the Actus with Sony. I agree with Steve that the bulk of the Pentax on a body that managed the lenses seems like a very inconvenient system to use in the real world. The X2 sounds great if you're in your studio/still life environment though.
    Remember: adventure before dementia!

    As Oscar Wilde said, "my tastes are simple, I only like the best"

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    Re: Cambo Actus Mini for Pentax 645

    Quote Originally Posted by Steve Hendrix View Post
    The flange distance isn't the only (nor even the primary) factor that negates a Cambo Actus/Pentax 645D-Z combo. The dimensions of the camera body itself will not fit on either Cambo Actus Mini or Actus DB, and if Cambo did produce an Actus just for the Pentax, then it would be a much larger view camera, which somewhat defeats the point of the Actus.

    However, there is a Cambo product that has precedence for this line of thought, and that is the Cambo X2 Pro.

    https://captureintegration.com/cambo/cambo-x-2-pro/


    Steve Hendrix
    CI
    Well this is, indeed, the sort of thing I'm looking for and if the Mamiya RZ lenses work for movements on a cropped 645 sensor this would be a great, (relatively) affordable solution. But alas the Pentax 645 is not listed among the compatible cameras (though size is not the reason, given that a Mamiya MF camera is listed). Too bad. (For me the Pentax 645 is key because the sensor is the cheapest MF game in town for what it offers, or so I think.)

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    Re: Cambo Actus Mini for Pentax 645

    i believe there is a blad cfv50-c back for sale on the forum at a good price...

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