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Modifying Legacy Manual Focus Lenses To Manual Diaphragm

 
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Harold Gough



Joined: 09 Mar 2008
Posts: 5788
Location: Reading, Berkshire, England

PostPosted: Thu Sep 27, 2012 1:37 am    Post subject: Modifying Legacy Manual Focus Lenses To Manual Diaphragm Reply with quote

A rather pretentious title for a simple procedure.

I know nothing about legacy AF lenses. This applies to MF ones.

Essentially, there are two types of diaphragm control for such lenses: those which remain wide open when detached from the camera and those which remain closed right down.

The former include Olympus OM and the latter include Nikon and Leica-R.

When reversed, or when mounted on some adapters, the groups which include Nikon and Leica-R have a totally manual diaphragm. When you select an aperture the diaphragm closes down to that setting until you alter it.

With OM, etc mounts, the adapters convert the lens to manual aperture function. However, the lens remains wide open when reversed. This simple little fix does what the adapter does but for a reversed lens.

In the two pictures I show the OM mount*. In the left one the lens is at maximum aperture when reversed. In the right one I have placed a small section of toothpick in the slot (with some highlighter ink for clarity) to push the diaphragm-closing lever clockwise and hold it against the spring and in the closed position. The diaphragm now stays at the aperture you set.

[

*Slight diffrences in the mount details are due to two different lenses being used.

I have set mine up as a temporary fix as I use the lens on my film camera.

Other strategies. Users of of adapters which close down the diaphragm could use one on the reversed lens as a hood, where this is practical. For Tamron Adaptall-2 lenses one adapter might be modified, another left unmodified, or a Nikon adapter migh be used instead of the one for the camera in use.

These issues surface every so often and this post might help someone.

Harold
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johan



Joined: 06 Sep 2011
Posts: 705

PostPosted: Thu Sep 27, 2012 2:18 am    Post subject: Reply with quote

Fyi - there's a better solution for old Nikon lenses - Nikon part E2 extension tube with stop down facility. Extension Ring E2 has a plunger which opens the automatic diaphragm of the Auto-Nikkor lenses to full aperture for brightest focusing. Then just take the finger off the plunger when you've focused and take the photo.
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Harold Gough



Joined: 09 Mar 2008
Posts: 5788
Location: Reading, Berkshire, England

PostPosted: Thu Sep 27, 2012 2:58 am    Post subject: Reply with quote

johan wrote:
Fyi - there's a better solution for old Nikon lenses - Nikon part E2 extension tube with stop down facility. Extension Ring E2 has a plunger which opens the automatic diaphragm of the Auto-Nikkor lenses to full aperture for brightest focusing. Then just take the finger off the plunger when you've focused and take the photo.

Thanks, Johan.

I'm sure that will help someone with Nikon lenses. I hoped folks with knowledge of other mounts would contribute here. All I have is a Tamron Adaptall-2 Nikon A/1 mount which came with some lens I bought! I suppose I could use that as I suggested* but I am not currently using Tamron lenses for macro, at least not ones which are candidates for reversing.

*[Edit] I have just checked it. It does give the fully manual function.[Edit ends]

Harold
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Last edited by Harold Gough on Thu Sep 27, 2012 4:46 am; edited 1 time in total
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johan



Joined: 06 Sep 2011
Posts: 705

PostPosted: Thu Sep 27, 2012 3:07 am    Post subject: Reply with quote

The thing about reversing lenses though is you can use any old mount on your cam. After all it's reversed so the mount is spectacularly irrellevant (unless you also want to use it the conventional way round). So anyone of any brand who wants a marginally easier solution to stopdown focusing can buy an old nikon lens together with this gadget! I bought one a few weeks ago on ebay for just over a tenner

In terms of other brands there's a novoflex thing for canon lenses that gives you aperture control. I nearly made one for Pentax a year ago (dead easy with some cat5 cable and a couple of extension rings) but the mechanical aperture defeated me. I did contact some guy to make me a doohicky gadget that used radio signals and 2 motors to click both the shutter and reverse aperture, but that started getting a bit too finnicky so I bailed out.
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Harold Gough



Joined: 09 Mar 2008
Posts: 5788
Location: Reading, Berkshire, England

PostPosted: Thu Sep 27, 2012 4:50 am    Post subject: Reply with quote

Johan,

I now have quite a ranger of Leica/Leitz lenses but have never owned a Leica camera. With those of ROM mount, which fit my adapter, it was a bonus that reversing gave manual diaphragm function.

Harold
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ChrisR
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Joined: 14 Mar 2009
Posts: 4065
Location: Near London, UK

PostPosted: Thu Sep 27, 2012 4:52 am    Post subject: Reply with quote

That would be for Canon FD lenses, not EOS ones, Johan?

I've thought of doohickeys too - there are some very fast and small servos and stepper motors out there.


--

I've mentioned this before but...
If you buy a Nikon G to Canon EOS adapter, you get a little lever to close the lens down. There's no aperture ring on a Nikon G lens.
So you can use it to put a Nikkor G reversed onto anything

---
Oh and - manual Olympus extension tubes have a tab to shut the lens down. The Tube doubles as a lens hood.
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