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Navitron 50/0.95 flange distance
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PostPosted: Fri May 20, 2011 5:09 pm    Post subject: Navitron 50/0.95 flange distance Reply with quote
Hi guys,

I snapped up a Navitron 50/0.95 on ebay a while ago to use as a "project" lens whenever I'd find a suitable body to hang it in front of. Now holding it in front of the Sony NEX I purchased recently, looks like I can focus to infinity(ish) when there's a few mm of air between the lens and the body.

I'm thinking of having an adapter made; the back of the lens has what seems to be a 54mm diameter thread (M54x0.5 mentioned on this page, http://www.abex.co.uk/sales/optical/fast_lenses/navitron_50f095/item.htm), and a NEX - 52mm thread macro reversal ring was easy to find on ebay, so it should be just a matter of getting a suitable ring done by a metal worker (I don't have the tools or the skill to do it myself).

Would be nice to know the exact flange distance, though. NEX flange distance is 18mm and with the air space needed for infinity focus it seems that the lens flange distance is somewhere around one inch but still, a silly millimeter makes a big difference in these matters as everyone knows, I'm sure. Google hasn't been helpful so far...

Any help would be appreciated! Also comments on the lens quality or sample images (I noticed there's one thread here on the lens on m4/3, but not many technical details)


PostPosted: Fri May 20, 2011 6:09 pm    Post subject: Reply with quote
I think it should not be difficult to make convert or adapt it to your camera. However, I doubt if it can cover the aps-c sensor.

update:
Found a flickr page of using this lens on NEX-3
http://www.flickr.com/photos/pcwang/sets/72157623156815821/with/5737735451/

and YAKUMO 50mm F0.95 TV on Lecia M mount(they should be the same lens?)
http://www.flickr.com/photos/doo3/2956539115/


PostPosted: Fri May 20, 2011 6:59 pm    Post subject: Reply with quote
Hi,

calvin83 wrote:
I think it should not be difficult to make convert or adapt it to your camera. However, I doubt if it can cover the aps-c sensor.


It does cover the sensor nicely. I haven't yet examined in detail whether there's any noticeable falloff in the corners, because I've just been handholding the lens close to the body, but initially at least there doesn't seem to be any major problem.

Possibly there are different versions of this lens around; the one I have certainly doesn't look like a C-mount lens. The thread mount is much wider (54mm vs 1 inch of C mount), and I wouldn't be able to reach infinity focus with a C-mount lens unless I was holding it inside the bayonet throat as C-mount flange distance is a tad shorter than NEX flange distance.

I will try to jury rig something from my odds and ends bin over the weekend and post some samples Smile


PostPosted: Sat May 21, 2011 3:25 pm    Post subject: Reply with quote
hmallat wrote:

I will try to jury rig something from my odds and ends bin over the weekend and post some samples Smile


Well, I couldn't find a suitable ring in my collection after all, so here's just one sample with lens hand-held in front of the body; it's meant just to demonstrate that the lens can cover the APS-C sized sensor of a NEX nicely. The picture isn't really sharp anywhere but that's at least to an extent due to the fact that the lens wasn't really attached to the body and that I haven't practised manual focusing with the NEX yet.



PostPosted: Tue May 24, 2011 5:30 am    Post subject: 54mm 54mm Reply with quote
Excellent score!

It might be worth gluing the rear to an adapter? The space in between could be filled with multiple step up/down rings or say an M42 to c mount adapter and then use a c mount adapter to fit to the body.

Only glue when satsified. I always helped Granny when sucking eggs too! Twisted Evil
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