Michael Floyd
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That's how I like 'em, just a snitch short!
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Pentax 645 lenses on Fujifilm GFX
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I can say I had a similar experience with the Fotodiox p645(a)- gfx adapter. I was walking out on a cold day in the park with gloves on (-20 C). I was trying to turn the zoom ring on my adapted 55-110 when I barely noticed it felt too loose. The lens dropped out of the adapter to the snowy ground and rolled in it with the helicoid focusing mechanism broken. (I managed to open it, glue up some parts and find the right beats to put it back together after a few attempts).
So my Fotodiox p645 (a) - gfx adapter mounts well but the release is very very easy to activate. The friction needed to rotate the lens to remove it from the mount is also very low. Be aware of this and I hope that some other forum members can share their experiences on this.
I ended up trying a cheap generic adapter and it works better. The friction is good, I can control the aperture on the lens (A, not FA) ring (except it wont close more then f16) and it is a little lighter too.
That throws off the distance scale. No zone focusing. If the lens has floating elements image quality is adversely affected.
AudiiDudii
Leading Member
I have heard of this happening, too, but have never experienced it personally.
In my specific case, the bayonet literally pulled off the screws, stripping their threads, as this photo shows:
As coincidence would have it, the tripod was positioned over a box mostly filled with bubble-wrap and the lens fell into it, so I initially thought it escaped damage.
But I was wrong and it apparently did manage to reach the bottom of the box and leave a dimple in the cardboard suggesting it did hit the tile marble floor underneath although not with the full force of gravity.
This was sufficient to leave a ding in the bayonet that made it slightly oval, hence it was difficult to remove from the lens. The aperture ring now has a rough spot halfway through its rotation and I can hear / feel something grinding inside. The focus ring feels fine but the zoom ring has a rough spot similar to the aperture ring, so it's clear there is some internal damage.
I don't know if this damage has affected the optical performance of the lens, because it doesn't matter at this point. That's because I can't imagine repairing it won't cost more than the $400-ish it will cost to replace (actually, $175, as I replaced my FA version with a slightly smaller and 10 percent lighter A version) so that was that. <sigh>
Unfortunately, for technical reasons, I had no alternative but to replace the lens bayonet with another, identical one, which I expect to be delivered within a few days.
This time around, though, I plan to re-drill the holes for the mounting screws larger, so I use M2 screws instead and I will likely increase their number while I'm at it, just to be on the safe side.
AudiiDudii
Leading Member
I agree with you on all points, although in my experience, misaligned floating elements are much less of an issue at longer focusing distances.
thanks for sharing!I have heard of this happening, too, but have never experienced it personally.
In my specific case, the bayonet literally pulled off the screws, stripping their threads, as this photo shows:
As coincidence would have it, the tripod was positioned over a box mostly filled with bubble-wrap and the lens fell into it, so I initially thought it escaped damage.
But I was wrong and it apparently did manage to reach the bottom of the box and leave a dimple in the cardboard suggesting it did hit the tile marble floor underneath although not with the full force of gravity.
This was sufficient to leave a ding in the bayonet that made it slightly oval, hence it was difficult to remove from the lens. The aperture ring now has a rough spot halfway through its rotation and I can hear / feel something grinding inside. The focus ring feels fine but the zoom ring has a rough spot similar to the aperture ring, so it's clear there is some internal damage.
I don't know if this damage has affected the optical performance of the lens, because it doesn't matter at this point. That's because I can't imagine repairing it won't cost more than the $400-ish it will cost to replace (actually, $175, as I replaced my FA version with a slightly smaller and 10 percent lighter A version) so that was that. <sigh>
Unfortunately, for technical reasons, I had no alternative but to replace the lens bayonet with another, identical one, which I expect to be delivered within a few days.
This time around, though, I plan to re-drill the holes for the mounting screws larger, so I use M2 screws instead and I will likely increase their number while I'm at it, just to be on the safe side.
Looking at the bright side, these pentax lenses are so affordable that it's less heartbreaking to replace them for people like us that like to use them in ways they were never intended to be used or in extreme situations. I once lost a brand new fuji x-pro1 that flooded in my backpack during a typhoon hiking trip in Hokkaido.
I guess that explains why I like to buy most of my gears used
AudiiDudii
Leading Member
Same here! I was born a frugalitarian and while I'm willing to spend money when I have no alternative to meet my needs, I prefer to spend as little of it as possible, whenever it's possible.I guess that explains why I like to buy most of my gears used
In fact, about the only things I ever buy new are the parts and materials I use to make my FrankenKameras and that happens only when I can't scrounge something suitable from my scrap or parts boxes!
We share a similar spirit !Same here! I was born a frugalitarian and while I'm willing to spend money when I have no alternative to meet my needs, I prefer to spend as little of it as possible, whenever it's possible.I guess that explains why I like to buy most of my gears used
In fact, about the only things I ever buy new are the parts and materials I use to make my FrankenKameras and that happens only when I can't scrounge something suitable from my scrap or parts boxes!
Not sure if here is the right place but I would love to see more of your FrenkenKams. Please share if you feel like it. Really like what Rob De Loe is doing too with his toyo.
Michael Floyd
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Thanks Jim, good points for sure.
The distance scale issue I'm aware of and it doesn't bother me in the slightest. I far prefer to have a tiny little bit of focus beyond infinity.
The floating elements requiring accurate flange distance is something I haven't thought about though, and is definitely something to consider. The great bulk of my lenses are group focusing so no problems there. However, the few that have floaters I will have to do some test on to see how much difference it makes.
I aim for 0.05mm short for adaptors, which is about 0.002% of the FFD for P645>GFX. Have you done any tests or trials around this potential issue that might suggest a range of acceptable tolerance?
When using a Cambo Actus or similar, is it possible to set the effective flange distance to this degree of accuracy? I'm wondering this as fussing with shims to test this out will be a whole lot more effort that winding a little geared wheel....
I dismountet the part of the lever (5 black screws), applied a bit silicone where the sliding wasn't going easy at all - and now it works.
my lenses sit well and tight on the adapter as well as it on the camera. thanks for the warnings though and the help!
my lenses sit well and tight on the adapter as well as it on the camera. thanks for the warnings though and the help!
Rob de Loe
Veteran Member
I would say no, it isn't possible to set the effective flange distance to anything remotely close to +/- 0.05mm.
The Pentax-A 645 35/3.5 is a mainstay on my VX23D outfit. I tried using it as a rail focusing lens. It work fine up to around 1m. From 1m and closer, the floating elements would be engaged using the helicoid. Comparing a test scene at <1m where one image was made rail focusing (lens set to infinity and focused by rail) and one was used properly (lens set to flange distance and focused with helical), the rail focused image was very poor in the corners, where the floating elements do their work. The centre was the same.
So on my VX23D I set the standards at flange distance, and then focus with the helical. A few caveats though:
1. When I used base tilt, as soon as I started using more than a tiny amount of tilt, flange distance went out the window. It was frequently necessary to set the lens to infinity on the helical and focus using the rail past infinity. It doesn't make sense why that works, but it did. With the axis tilt system I installed this year, things work more normally, in other words, I can set to flange distance on the rail and do everything with the lens' focus ring.
2. I'm not at all confident that I'm actually at the correct flange distance on the rail when I set up. I've measured as best I can, but I could easily be off by way more than the 0.05mm you asked about. In my experience, it hasn't made a huge difference whether I'm at precisely the correct flange distance. It's safe to say I'm not each time I set up, except by coincidence.
3. Even if you can set it to exactly the flange distance on the rail, is it the correct flange distance vertically and horizontally on your Actus? In other words, can you be sure that your standards are perfectly aligned in every dimension, and that they didn't go out of alignment by a tiny amount since the last time you aligned them? On my VX23D, I cannot be sure that they are in perfect alignment, yet things work out fine if I'm "close".
Michael Floyd
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Good one! Well done.
Michael Floyd
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Good one - thanks for the reply Rob. That all makes perfect sense.
It sounds like 'close enough' is usually good enough. I daresay I'll one day shim my adaptor out to exact FFD and do a comparison with my ever so slightly short current setup. It would be nice to be able to put a number on just how far things can be out before a noticeable difference occurs.
I must say, all this view camera talk ( ???? = what is the generic term for this kind of camera, with standards and movements, even if it is not large format?) has me very intrigued and interested. I've been playing around with a very loose setup that will no doubt give you guys a bit of a chuckle. It's really just one small step up from freelensing, which I enjoy and do a bit of. Nevertheless it is teaching me about what movements have what effect in a more controlled way. Cost is thus far nothing and it may inform whether and/or in what way I might proceed with this path.
Rob de Loe
Veteran Member
My pleasure!
It's a good question. I haven't spent a lot of time on that simply because the way my VX23D works, it's not possible to get the standards in exactly the same position twice in a row. The best I've been able to do is find infinity empirically for P645 lenses (at night, focusing on stars), and then add labels that mark the position of the standards. There's lots of room for error there because I'm lining the edge of the standard up against a pencil line by eye. So it really is just "close enough"
I call mine a "digital view camera", which I think is reasonable given that the design and movements matches the 4x5 cameras that everybody called view cameras!
Good on you! Experimenting is a great way to learn. An easy next step is a tilt-shift adapter. For a lot of people that's all they need or want. The Fotodiox Tilt ROKR I have is probably the best and cheapest way to use your Pentax 645 lenses. There are a few things you can do to make it much more usable, starting with using an inexpensive lens collar around the front of the adapter: https://www.dpreview.com/forums/thread/4548327has me very intrigued and interested. I've been playing around with a very loose setup that will no doubt give you guys a bit of a chuckle. It's really just one small step up from freelensing, which I enjoy and do a bit of. Nevertheless it is teaching me about what movements have what effect in a more controlled way. Cost is thus far nothing and it may inform whether and/or in what way I might proceed with this path.
Rob de Loe
Veteran Member
To follow up on this point... today I was using some new long lenses and noticed that at wide apertures, they were both doing very well on one side of the image, but poorly on the other.
Sure enough, the front standard was slightly misaligned -- enough to cause a bit of unintentional swing that became quite noticeable with long lenses at wide apertures. It was a very small amount; the bubble was just barely past the line on one side, but that was all it took.
One thing I love about the Toyo VX23D is it's easy to fix that problem. And one thing I don't love is that it's probably easy to fix all the problems, but there's no manual! If Toyo ever published a service manual, it does not seem to have made it onto a scanner, so repair and adjustment involves a lot of trial and error.
My VX23D in the alignment setup, with standards back in level
The point of this story is that I'm willing to bet that many instances of people adapting a lens to a camera and then posting on a forum that the lens has "tilted elements" or some other problem they attribute to the lens are actually dealing with an adapter problem.
If I'm testing an adapted lens and it looks like there's tilt, I try it with a couple of other adapters.To follow up on this point... today I was using some new long lenses and noticed that at wide apertures, they were both doing very well on one side of the image, but poorly on the other.
Sure enough, the front standard was slightly misaligned -- enough to cause a bit of unintentional swing that became quite noticeable with long lenses at wide apertures. It was a very small amount; the bubble was just barely past the line on one side, but that was all it took.
One thing I love about the Toyo VX23D is it's easy to fix that problem. And one thing I don't love is that it's probably easy to fix all the problems, but there's no manual! If Toyo ever published a service manual, it does not seem to have made it onto a scanner, so repair and adjustment involves a lot of trial and error.
My VX23D in the alignment setup, with standards back in level
The point of this story is that I'm willing to bet that many instances of people adapting a lens to a camera and then posting on a forum that the lens has "tilted elements" or some other problem they attribute to the lens are actually dealing with an adapter problem.
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Rob de Loe
Veteran Member
That's a good approach. I do that when I can, but in this case the only adapter these lenses can go on is the one in the picture.
Michael Floyd
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Thanks Rob.
'Digital View Camera' it is then! And I will carry on using my intentionally short adaptor without too much concern until such time that I get around to doing some well controlled tests, safe in the knowledge that Mr Cambo and Mr Toyo are probably at least as far off the official mark on any given day.
The lens collar for T/S makes great sense, I'll remember that for the future.
I know the fotodiox adapters have a smooth aperture ring built in without numbers. However I would love to use pentax 645 lenses in studio to set lighting and then transfer the exact aperture settings over to my rz67 to shoot alongside. Do older, manual pentax lenses work to turn the actual aperture ring on the lens? Or do you completely rely on the fotodiox ring for aperture?
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