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martyn_bannister
![Level 3 Level 3](rating3.gif) Joined: 23 May 2010 Posts: 1151
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Posted: Mon Apr 04, 2011 6:09 pm Post subject: Exakta lenses - ? |
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martyn_bannister wrote:
Hi all,
Can someone tell me what the deal is with Exakta (Exa?) lenses? I have bought a Triotar 135/4 (for which I think I paid too much) and a Flektogon 35/2.8 (for which I think I paid too little) and there is NO WAY either of these lenses will get even NEAR infinity focus on either of my Canons.
I have tried manually holding both lenses up to both my 10D and my 5D and they are both MILES away from focus even when stuffed as far into the camera as they will go, never mind trying to miss the mirror on either body.
Is there a difference between EXA and EXAKTA mounts and are there some lenses/mounts which WILL focus to infinity on a Canon and some that WON'T???
Or am I doomed to near focus shooting or selling them again?
Any help appreciated. |
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RioRico
![Level 3 Level 3](rating3.gif) Joined: 12 Mar 2010 Posts: 1120 Location: California or Guatemala or somewhere
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Posted: Mon Apr 04, 2011 9:56 pm Post subject: |
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RioRico wrote:
This is very curious. Do these lenses have simple bayonets, or do they have the stop-down button sticking off the side? I say it's curious because of these lens registers (flange focal distances):
Canon EOS: 44mm
Exakta/Exa: 44.7mm
Pentax/M42: 45.46mm
Longer register lenses should achieve infinity focus on shorter register cameras. I have worked up a simple conversion that lets me obtain infinity focus with Exakta lenses on my PK-mount Pentax K20D -- I remove and save the tiny protruding screw from the Exakta mount and glue an M39-M42 adapter ring around the bayonet. I have grioud 0.8mm from the flange of a cheap infinity-focus M42-PK adapter. I screw the slightly adapted Exakta lens into that modified adapter, and infinity focus is mine!
I don't mess around with EOS cams so I'm not familiar with M42-EOS adapters, but a similar approach should work. Are you *sure* that these are Exakta-mount lenses? Pictures might help. Good luck! _________________ Too many film+digi cams+lenses, oh my -- Pentax K20D, K-1000, M42s, more
The simple truth is this: There are no neutral photographs. --F-Stop Fitzgerald |
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woodrim
![Level 4 Level 4](rating4.gif) Joined: 14 Jan 2010 Posts: 4058 Location: Charleston
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Posted: Mon Apr 04, 2011 11:51 pm Post subject: |
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woodrim wrote:
You actually have to hold it .7mm farther out , not stuff it in. Exacta is a relatively small mount. _________________ Regards,
Woodrim |
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martyn_bannister
![Level 3 Level 3](rating3.gif) Joined: 23 May 2010 Posts: 1151
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Posted: Tue Apr 05, 2011 5:51 am Post subject: |
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martyn_bannister wrote:
RioRico wrote: |
This is very curious. Do these lenses have simple bayonets, or do they have the stop-down button sticking off the side? I say it's curious because of these lens registers (flange focal distances):
Canon EOS: 44mm
Exakta/Exa: 44.7mm
Pentax/M42: 45.46mm
Longer register lenses should achieve infinity focus on shorter register cameras. I have worked up a simple conversion that lets me obtain infinity focus with Exakta lenses on my PK-mount Pentax K20D -- I remove and save the tiny protruding screw from the Exakta mount and glue an M39-M42 adapter ring around the bayonet. I have grioud 0.8mm from the flange of a cheap infinity-focus M42-PK adapter. I screw the slightly adapted Exakta lens into that modified adapter, and infinity focus is mine!
I don't mess around with EOS cams so I'm not familiar with M42-EOS adapters, but a similar approach should work. Are you *sure* that these are Exakta-mount lenses? Pictures might help. Good luck! |
The Triotar is a simple bayonet. The Flekogon has the same bayonet and an aperture button on the side. I'll post pics of the mounts if I get a second today. |
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luisalegria
![Level 4 Level 4](rating4.gif) Joined: 07 Mar 2008 Posts: 6602 Location: San Francisco, USA
Expire: 2018-01-18
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Posted: Tue Apr 05, 2011 6:04 am Post subject: |
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luisalegria wrote:
As I understand it there are plenty of Exakta-Canon adapters available.
Because the Exakta and Canon register distances are so close, the adapter maker has to be careful of tolerances. It is easy to make one that is too thick. Some Exakta-Canon adapters don't give infinity on some lenses, particularly wide angles, because they are a bit too thick.
There were some posts here some time ago about "shaving" some adapters to fix that problem. _________________ I like Pentax DSLR's, Exaktas, M42 bodies of all kinds, strange and cheap Japanese lenses, and am dabbling in medium format/Speed Graphic work. |
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martyn_bannister
![Level 3 Level 3](rating3.gif) Joined: 23 May 2010 Posts: 1151
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Posted: Tue Apr 05, 2011 6:09 am Post subject: |
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martyn_bannister wrote:
luisalegria wrote: |
As I understand it there are plenty of Exakta-Canon adapters available.
Because the Exakta and Canon register distances are so close, the adapter maker has to be careful of tolerances. It is easy to make one that is too thick. Some Exakta-Canon adapters don't give infinity on some lenses, particularly wide angles, because they are a bit too thick.
There were some posts here some time ago about "shaving" some adapters to fix that problem. |
This is what I had read and understood. Hence my surprise and frustration when both of these lenses seem so far away from attaining infiniy focus. |
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luisalegria
![Level 4 Level 4](rating4.gif) Joined: 07 Mar 2008 Posts: 6602 Location: San Francisco, USA
Expire: 2018-01-18
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Posted: Tue Apr 05, 2011 6:25 am Post subject: |
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luisalegria wrote:
There is only one other Exakta mount, the uncommon external bayonet seen on some large lenses. Most Exakta bodies have the external flanges for these. And there are no commercial adapters for the external bayonet, though I have made one for a Meyer 300/4.5
For certain your lenses don't have this mount.
But other than that an Exakta mount is an Exakta mount. I have used Exaktas for 30 years and I haven't seen any lenses that have anything significantly different.
You may be getting something wrong by holding your lenses up to the lens opening. Why not try an adapter ? _________________ I like Pentax DSLR's, Exaktas, M42 bodies of all kinds, strange and cheap Japanese lenses, and am dabbling in medium format/Speed Graphic work. |
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martyn_bannister
![Level 3 Level 3](rating3.gif) Joined: 23 May 2010 Posts: 1151
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Posted: Tue Apr 05, 2011 6:50 am Post subject: |
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martyn_bannister wrote:
luisalegria wrote: |
There is only one other Exakta mount, the uncommon external bayonet seen on some large lenses. Most Exakta bodies have the external flanges for these. And there are no commercial adapters for the external bayonet, though I have made one for a Meyer 300/4.5
For certain your lenses don't have this mount.
But other than that an Exakta mount is an Exakta mount. I have used Exaktas for 30 years and I haven't seen any lenses that have anything significantly different.
You may be getting something wrong by holding your lenses up to the lens opening. Why not try an adapter ? |
I think you are right. Maybe I am panicking unecessarily. Here are the two mounts in question.....
The TRIOTAR is just a question of removing the tiny latch screw.
The Flektogon will be more difficult because of the pad next to the stop down button. Is it possible to remove the stopdown button entirely?
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