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Quick and dirty image circle comparisons
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PostPosted: Fri Dec 09, 2016 3:22 pm    Post subject: Quick and dirty image circle comparisons Reply with quote

I was playing around with my Industar 69 28mm f/2.8 on my Sony NEX 5n with my new adapter (thanks Chris) when I wondered what its image circle was like and if it would make sense to use it on my full frame A7. The quick and literally dirty (I know, I should have cleaned my sensor) answer is no:

Industar 69 28/2.8


So my next question was, do any of my other small wide angle lenses not designed for full frame come close?

Carl Zeiss Tevidon 25/1.4


Carl Zeiss Tevidon 35/1.9


Carl Zeiss S-Planar 32/4


Schneider Cine Xenon 25/1.4


Schneider Xenoplan 28/2.0


Kern Macro Switar 26/1.1


Rodenstock Rodagon 35/4


PostPosted: Fri Dec 09, 2016 3:40 pm    Post subject: Reply with quote

So from that I concluded that the only reasonable candidate for full frame is the Rodagon 35mm, the photo shown is taken wide open, stopped down the vignetting is almost entirely gone (but an embarrassing amount of dirt is visible). I was surprised to see the Xenoplan 28/2.0 have such a large image circle, it is a tiny lens, almost as small as the S-Planar 32/4. Both are perfectly suitable for APS-C, in my opinion. I have a broken Olympus Mju lying around somewhere, its 35/2.8 lens is supposed to be quite good and tiny and it should fill the 24*36mm frame without problem. More experiments for long winter evenings..

Of course, I'm showing illumination circles here, the image quality at the edges can be so low that image circle should be considered to be a bit smaller.


PostPosted: Fri Dec 09, 2016 6:39 pm    Post subject: Reply with quote

Very nice, thank's for sharing. Can you show which Schneider Xenoplan 28/2.0 variant it is?


PostPosted: Fri Dec 09, 2016 6:41 pm    Post subject: Reply with quote

THX Dick, very helpful and correlates well with my own findings!


PostPosted: Fri Dec 09, 2016 7:06 pm    Post subject: Reply with quote

Pancolart wrote:
Very nice, thank's for sharing. Can you show which Schneider Xenoplan 28/2.0 variant it is?


Sure, it's this one:


AFAIK the optics of the variants are the same, the differences are in the type of barrel, focus mechanism and aperture ring. This one is designed for rugged industrial applications, I think, and has a lockable aperture and focus. To focus you screw the lens into a C mount ring (the chrome ring on the rear) with a very narrow pitch. Very precise but not that user friendly. If I were to use such a lens on a regular basis, I would probably make an adapter to fit it onto an M39 or M42 helicoid, sacrificing some precision to gain ease of use. I actually use two other Xenoplans a lot, a 23/1.4 and a 35/1.9. These have considerably smaller image circles but as I use them reversed as high magnification macro lenses that doesn't matter. I unscrew the chrome ring and then they weigh just 50 grams - no excuse not to bring them along.

I bought a few of these on a camera fair once and I'm selling a set at the moment - check my post in the Marketplace section.


PostPosted: Fri Dec 09, 2016 7:25 pm    Post subject: Reply with quote

kds315* wrote:
THX Dick, very helpful and correlates well with my own findings!


You're welcome - it isn't science if it can't be reproduced Wink

I've also been looking at image circles of other lenses in my collection, and in a fit of rationality I've put some of those I haven't used in a long time on ebay. And some that I had multiple copies of..

It seems that there are quite a few C mount lenses where the C mount itself is a limiting factor for the image circle. My Schneider Tele Xenar 150/4 in C mount doesn't fill my Sony A7 frame, whereas the same lens in Robot Royal mount does. Actually, all the Robot Royal lenses I've used, 75mm, 90mm, 100mm, 110mm and 150mm, cover full frame.


PostPosted: Fri Dec 09, 2016 9:54 pm    Post subject: Reply with quote

Some more image circle indications:

Schneider Xenoplan 23mm f/1.4 C mount



Schneider Xenoplan 35mm f/1.9 C mount



Schneider Xenon 50mm f/2.0 C mount



Schneider Cine-Tele-Xenar 75mm f/2.8 C mount: its diameter at the C mount is too wide to fit my adapter, so I couldn't focus to infinity properly



Schneider Tele-Xenar 150mm f/4 C mount



Carl Zeiss Jena Tevidon 10mm f/2.0 C mount



Carl Zeiss Jena Tevidon 16mm f/1.8 C mount



Docter Optics Tevidon 50mm f/1.8 C mount



Carl Zeiss Jena Tevidon 70mm f/2.8 C mount



Carl Zeiss Jena Tevidon 100mm f/2.8 C mount



Linos MeVis-C 35mm f/1.6



Linos MeVis-C 50mm f/1.8


PostPosted: Fri Dec 09, 2016 10:29 pm    Post subject: Reply with quote

And a final few, slightly less systematic..

All enlarger lenses I've tried with a focal length of 50mm or more covered full frame:

Carl Zeiss S-Planar 60mm f/4



Computar dL 55mm f/1.9



Some projector lenses I used, be aware that when focussing closer, the image circle gets larger. Also, I using improvised adapters, not properly aligned or anything.

Astro-Kino-Color IV 50mm f/1.4



Astro-Kino-Color IV 75mm f/1.6



Isco-Goettingen Cinelux Xenon 65mm f/1.6



SOM Berthiot Paris Cinor Projection 75mm f/1.5



And a few weird catadioptric lenses I was handholding in front of my Sony A7:

Canon CL 250mm f/4



Minolta Vectis 400mm f/8


The irregular vignetting is caused by the rear lens baffle, if I get around to making a proper adapter/conversion it will cover full frame.


PostPosted: Fri Dec 09, 2016 11:28 pm    Post subject: Reply with quote

Cool, I was thinking it might be useful to start a database with image circle measurements from slr and RF lenses for the coming proliferation of the mini medium format that's starting to become affordable, like the new Fuji GFX 50S.


PostPosted: Sat Dec 10, 2016 5:03 pm    Post subject: Reply with quote

Lightshow wrote:
Cool, I was thinking it might be useful to start a database with image circle measurements from slr and RF lenses for the coming proliferation of the mini medium format that's starting to become affordable, like the new Fuji GFX 50S.

+1 i am sure some DDR classic lenses go beyond full frame


PostPosted: Sat Dec 10, 2016 8:20 pm    Post subject: Reply with quote

If you like square aspect ratio images (1:1), some lenses that are designed for smaller sensors can be used on larger sensor cameras if you crop out the vignetted areas. Of course you will be losing some of your megapixels, but that is no different than using a lens that covers the entire sensor and then cropping it square.


PostPosted: Fri Dec 16, 2016 4:00 pm    Post subject: Reply with quote

And a few more:

Astro Kino Color IV 75/1.6

I haven't got a good adapter that allows infinity focus for this lens, so this may be a tiny bit tilted.


Meopta Meostigmat 70/1.4

Also this is just an indication of the image circle, the lens is not perfectly perpendicular to the sensor.


Rodenstock XR Heligon 100/1.5

I can't adapt this one in a way that allows infinity focus yet, this is the maximum focus distance at the moment. About 2 meters.


PostPosted: Tue Jan 17, 2017 2:16 pm    Post subject: Reply with quote

And another one, the Schneider Kreuznach Cinegon 8mm f/1.4. This is a lens similar to the Xenoplans shown above, with the same 22mm to C-mount focussing adapter. This is a fixed aperture (f/2.0) version.



As you can see, this has a very small image circle. However, as I intend to use it reversed as an extreme macro lens that doesn't bother me too much:



A quick and dirty magnification test shows around 6mm filling the frame of my Sony A7, so I get a magnification of 6:1. The working distance is rather limited though.

I couldn't resist buying a few of these new in box, I'm selling one at the moment, see the marketplace section.


PostPosted: Tue Jan 17, 2017 2:20 pm    Post subject: Reply with quote

Like 1 Like 1 Like 1


PostPosted: Mon May 07, 2018 9:33 pm    Post subject: Reply with quote

I have yet more toys to be tested:

Linos Mevis-C 16mm f/1.6:

A much smaller image circle than the other Mevis lenses I tested.

Schneider Apo Xenoplan 20mm f/2.0:

The rear of the lens is too wide to fit into my C mount adapter properly, so I can't get anywhere near infinity focus. It is clearly of of the anti-shading series, with a much larger image circle than most C mount 20mm lenses.



Schneider Apo Xenoplan 35mm f/2.0:


Its C mount focus adapter restricts the image circle a bit, the next one is without the C mount, with an M30 to M42 and M42 to Sony E adapter:



PostPosted: Mon May 07, 2018 11:36 pm    Post subject: Reply with quote

Sticky?


PostPosted: Tue May 08, 2018 9:32 am    Post subject: Reply with quote

Nice thread... Wink

Fujinon 75mm 1.8 c-mount on FF


PostPosted: Wed May 16, 2018 2:33 pm    Post subject: Reply with quote

And another weird C mount lens, a Pentax TV zoom lens 8-48mm 1:1.0. Its wide C mount wouldn't fit in my C mount adapter, so I freelensed it. Please ignore the flare. As to be expected, it has a very small image circle, both at 8mm and 48mm

8mm




48mm


PostPosted: Wed May 16, 2018 3:38 pm    Post subject: Reply with quote

Wow, that Fujinon 75mm exhibits a remarkable amount of detail.

There are none on US eBay at the moment -- unfortunately Sad