m42 tubes and FF vignetting

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elimoss
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Joined: Wed Sep 12, 2018 11:31 am

m42 tubes and FF vignetting

Post by elimoss »

I have been using a bellows for 1-5x work on Sony FF. I adapt the bellows to Sony FE.

I would like to use tubes instead. I have plenty of m42 tubes lying around, but I am worried that flocked m42 tubes will cause some vignetting of the full frame image circle.

Does anybody have experience with using m42 tubes on full frame?

enricosavazzi
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Re: m42 tubes and FF vignetting

Post by enricosavazzi »

elimoss wrote:I have been using a bellows for 1-5x work on Sony FF. I adapt the bellows to Sony FE.

I would like to use tubes instead. I have plenty of m42 tubes lying around, but I am worried that flocked m42 tubes will cause some vignetting of the full frame image circle.

Does anybody have experience with using m42 tubes on full frame?
The Sony FE lens mount is barely wide enough not to vignette the sensor corners. This means that a short M42 to Sony FE adapter has to be narrower than the lens mount by 2-3 mm, and M42 tubes further reduce the diameter by another 2-3 mm. A thick flocking adds another 1 mm or so.

Whether vignetting or darkening of the corners occurs depends on the lens (smaller rear element is better), aperture (stopping down is often, but not always better), and on its distance from the sensor (closer is better), but M42 extension tubes directly attached to an M42 to Sony adapter (ID around 39-40 mm) are already narrower than the diagonal of the sensor (40.69 mm). If the rear element of the lens is wide (e.g. Printing Nikkors, some scanner Nikkors) it will cause some darkening of the corners.

My solution is to use wider tubes (e.g. M52) and adapter (M52 male to Sony FE "reversing ring"), or to mount M42 tubes onto a longer adapter (e.g. Metabones Nikon F to Sony FE, via M42 to Nikon F adapter).
--ES

JohnyM
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Post by JohnyM »

I dont remember seeing lenses that would start to show vignetting when used with m42 tubes (EVERYTHING i use have m42 screw somewhere) but didnt vignette by their own design. On the contrary, it usuakky was dissapearing...

FF is 43,5mm diagonal, so everything in m42 system was already smaller than film. As long as you use normal (not slim) m42 adapter you should be just fine.

I use black matte PAINT instead of flocking.

enricosavazzi
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Post by enricosavazzi »

I can confirm that the Sony A7R II with Printing Nikkor 105 mm at f/2.8 mounted via M42 to Sony FE short adapter shows darker corners than with a properly sized adapter and tubes. There is no doubt that the problem is real.
--ES

dickb
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Post by dickb »

Like Enrico said, m42 tubes certainly can lead to vignetting with specific lens / adapter combinations. With my m42 tubes, the inner diameter varies a lot. Some even have aperture lever push pins that take up inner diameter real estate. Helicoid extension rings tend to be narrower as well.

If you use multiple m42 extension rings, use the narrower ones close to the lens and the wider ones close to the camera to minimise problems.

elimoss
Posts: 41
Joined: Wed Sep 12, 2018 11:31 am

Re: m42 tubes and FF vignetting

Post by elimoss »

enricosavazzi wrote:
My solution is to use wider tubes (e.g. M52) and adapter (M52 male to Sony FE "reversing ring"), or to mount M42 tubes onto a longer adapter (e.g. Metabones Nikon F to Sony FE, via M42 to Nikon F adapter).
Thank you for all the information and tests, Enrico.

I'll try the Nikon F to Sony FE adapter (long, like the Metabones) and then an m42 to nikon F ring, following by m42 tubes, since I already have that lying around.

But I have a feeling that 52mm is the way to go to really be free of vignetting concerns

ray_parkhurst
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Post by ray_parkhurst »

For sure this problem is real, and indeed it foiled some plans I had to directly replace my Canon camera with Sony using short adapter. I was hoping to get the benefit of short register without having to change my M42 bellows, but the system showed vignetting. I had to go with long adapter made for M42 to test the Sony FF camera without changing to different bellows, and this limited my ability to test the Sony with short lenses.

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