Exacta lenses (and EOS adapter)

[Orio]

Is it possible to remove that "bulge" from the Exacta lenses that have it?
I ask because the hong kong adapter I have found, talks about the bulge as being able to not clear the wat to the rotation of the bayonet inside the EOS cameras.
This surely must be verified (the 5D for instance not having the builtin flash should not have this problem), but for the moment I'd like to know it that bulge is removable by unscrewing, etc....

Thanks!

[rick_oleson]

I assume you're talking about the arm that has the shutter release button and the auto diaphragm system in it? No, you can't remove that. And I expect that it would interfere with the overhanging prism on the 400D, but I think the higher end models without built-in flash would be okay.

:)=

[Orio]

Thanks Rick!
I need to find an Exakta lens with bulge to test on the 5D.
If I can mount that, a whole universe of much cheaper Exakta version lenses will open!
For instance, the Flek 4/20 for Exakta is usually sold at about half the price of the M42 version.

[hacksawbob]

Hi Orio I have a pancolar exacta with bulge here. my thoghts were perhaps to mount the lens 180or 90 degrees out by modifying the EOS side there by retaining the register distance... maybe I can send it for testing

[Orio]

Bob the seller of the adapter wrote that the adapter is incompatible with the "bulged" exaktas.
So even if there was room enough on the 5D to mount one, there would not be an adapter for it.
Too bad, there is plenty of Flektogon 25mm lenses for exakta that are so appetizing!

[bob955i]

You can remove the aperture button mechanism ("the bulge") from the later CZJ lenses.

There's a little bit of work involved, but I can show you how to do this if necessary.

It's completely reversible too...

[Orio]

Thanks Bob, but I would still be without the adapter.

[Attila]

Exakta camera register distance is 44.7, EOS register distance is 44.0. I am afraid this is not a real opportunity to use Exakta's wide angle lenses. I don't belive this adapter will maintenance infinity focus.0.7 mm simple not enough to make right adapter.

[bob955i]

@ Orio:

I think what the seller may mean about incompatibility is regarding the front of the 5D's pentaprism preventing the Exakta "bulge" from rotating past when you mount the lens.

Remove the "bulge" and you should be able to mount the lens using the adapter.

However, Attila's correct - there's another Exakta-EOS adapter made by Kindai and from various reports I've read, it too doesn't quite allow true infinity focus for the same reason. And it's daaaaaamn expensive......

That said, nothing's impossible.......

[hacksawbob]

My understanding was that the lens would fit the adapter but the two together would not fit the camera as lens bulge and flash would collide. So if the lens were mounted off-set this would not be an issue. I have just tried with my M42 adapter and it will mount to the Eos if you place it onto the camera ithe the red marker at abot 5 Oclock instead of 12 Oclock. all that is needed is to drill a new hole for the locking pin on the camera to prevent the lens rotating too far. The f stops and focusing numbers will be on the underside but that is not the end of the world.

[Orio]

[bob955i]

I've had a look at my Exakta mount lenses and I think I know what he's referring to - on the "bulge" lenses, the aperture mechanism has a cover with a small protrusion that looks like it may foul the adapter and thus prevent it from mounting. The actual Exakta bayonet sits proud of the camera front so this protrusion never causes a problem.

If you remove the aperture mechanism, I would think you'd be able to use the adapter.

I can post images of the points I'm referring to.

[hacksawbob]

Can you tell me which part you think will cause a problem?

[Orio]

If you have doubt, you can ask the seller directly:

Click here to see on Ebay

His name is Eric.

[lulalake]

[hacksawbob]

OK I contacted eric with this picture here is his response, "part A blocks the protruding top of EOS, and part B and C block the adapter"

now looking it this if you can remove the plate with B and C we may be in business

[bob955i]

@ Orio: Part B would foul the adapter, and part A, the mirror pentaprism like the seller says.

@ Bob:

The plate tensions the shutter/aperture button by means of a compression spring - remove the plate and the button and spring fall out, but you're still left with the "bulge".

[lulalake]

[bob955i]

Here it is guys:

No pix but once you get in there, it's pretty straightforward and it covers all the '60s CZJ Exakta automatic glass as they all used the same mount albeit with some minor differences.

1. Remove four screws around circumference of lens mount and detach it – place screws and lens to one side for now.

2. Remove two screws securing rear plate of aperture/shutter release housing – press down on plate as you remove screws to prevent it from springing up suddenly.

3. Remove aperture/shutter release tension spring and button.

4. Remove screw inside aperture/shutter release housing.

5. Remove small circlip from cam pin directly opposite above screw.

6. Lift off cam, taking care not to lose small tension spring.

7. Remove cam pin using suitable tool – it has two diametrically opposite slots at its base.

8. Detach aperture/shutter release housing.

9. Remove two screws adjacent to bayonet stop pin.

10. Remove aperture actuating arm, taking care not to lose small tension spring.

11. Refit lens mount.

12. Cover hole in mount using insulating tape etc.

13. Enjoy your preset Exakta lens...

If you decide to restore the lens back to original, as well as naturally keeping all the parts you remove, take note that refitting the spring in step 10 is extremely fiddly and will severely try your patience.....

[Orio]

Thank you Bob for the detailed description. Maybe one day I will try it.

[hacksawbob]

PING what was that? it was my spring flying off across the kitchen to God knows where, I hope it turns up again!

[bob955i]

Wait until you try to refit the tiny spring I referred to in step 10......

They've only just allowed me to be in the vicinity of large heavy tools and sharp instruments.

And I still break out in a cold sweat if anyone mentions the word "spring"......

[lulalake]

Bob,
Thanks so much but s***, now I need to buy an adapter and some P. lenses before they get too expensive!

Jules