Home

Please support mflenses.com if you need any graphic related work order it from us, click on above banner to order!
SearchSearch MemberlistMemberlist RegisterRegister ProfileProfile Log in to check your private messagesLog in to check your private messages Log inLog in

Contax 50mm: Aperture blades problem
Post new topic   Reply to topic
Home   Manual Focus Lenses
View previous topic :: View next topic  


PostPosted: Sun Oct 31, 2010 6:31 pm    Post subject: Contax 50mm: Aperture blades problem Reply with quote
A couple of months ago I bought a 50mm Planar on eBay which looked in great shape.
It really is, except that when stopping down from f11 to f16, the aperture ring was more stiff and you have to exert greater pressure.
"Who cares?", I thought, as I rarely use f16.

The real problem is that when used on my 5D II with an adapter, the problem appears as early as f4 --> f5.6.
Sometimes, the aperture ring turns, but the aperture remains the same. I have noticed that
unscrewing the lens a bit, makes the aperture blades move to the right position.
But this is very irritating and not a solution when you are in a hurry.
In general, when the lens is not mounted, the aperture works more or less fine.
Perhaps the problem is amplified by the adapter, but it happens with 2 adapters by different manufacturers.

Is there a way to fix this?
It is the MM version, SN 809XXXX

Thank you.


PostPosted: Mon Nov 01, 2010 1:12 am    Post subject: Reply with quote
One probable cause of this problem is with the lens aperture opening lever. For some Contax lenses and Canon FF bodies, this lever ( its only function is for Contax camera bodies, that irrespective of chosen aperture setting, it opens up the aperture fully for focusing, it retracts to let the aperture to stop down just before exposure) could touch the matte box (above the AF electrical connectors and below the mirror ) and get stuck. In this case, the aperture would be kept at either fully open or some other settings. You can check if there is any scratch mark inside the lens mount, if scratches can be found, this is the cause. The lever can be filed down a bit and it would not get stuck, the aperture movement would be free again. Good luck and have fun checking...


PostPosted: Mon Nov 01, 2010 1:17 am    Post subject: Reply with quote
Nikos, I had the same problem with all the copies that I tried (three).
It is a problem that comes out of the interaction of three elements: the lens, the adapter, and the camera.
For instance, the same combination lens-adapter that does not work on my FF cameras, did work with the 50D.
So one actor is the camera and specifically what is different between the 5D (I and II) and the 50D.
Another actor must be the adapter, because there is people who reported to have used the lens successfully with their adapters. My adapters don't work, but I can't tell about other adapters.

I finally solved the problem by... buying the ZS version of the lens Rolling Eyes


PostPosted: Mon Nov 01, 2010 10:11 am    Post subject: Reply with quote
cambug wrote:
One probable cause of this problem is with the lens aperture opening lever. For some Contax lenses and Canon FF bodies, this lever ( its only function is for Contax camera bodies, that irrespective of chosen aperture setting, it opens up the aperture fully for focusing, it retracts to let the aperture to stop down just before exposure) could touch the matte box (above the AF electrical connectors and below the mirror ) and get stuck. In this case, the aperture would be kept at either fully open or some other settings. You can check if there is any scratch mark inside the lens mount, if scratches can be found, this is the cause. The lever can be filed down a bit and it would not get stuck, the aperture movement would be free again. Good luck and have fun checking...


+1 I've had this happen too with a Contax 35-70/3.4, although it didn't affect the aperture ring at all, just the aperture itself (wouldn't close).


PostPosted: Mon Nov 01, 2010 10:52 am    Post subject: Reply with quote
cambug wrote:
The lever can be filed down a bit and it would not get stuck, the aperture movement would be free again. Good luck and have fun checking...


Thank you!

Instructions for filing a small and moving part?


PostPosted: Mon Nov 01, 2010 2:58 pm    Post subject: Reply with quote
Orio wrote:

I finally solved the problem by... buying the ZS version of the lens Rolling Eyes

Which is, by the way, out of stock. As is the ZE version...


PostPosted: Mon Nov 01, 2010 6:09 pm    Post subject: Reply with quote
nkanellopoulos wrote:

Instructions for filing a small and moving part?


Here is how I did this on a Carl Zeiss 50mm f/1.7. I covered the rear glass element with gaffa tape - stretched, so that it does not touch the glass itself. Closed the opening of the lever with some plastiline, to avoid metal dust falling inside the lens.
Then I used a metal file to shorten the lever by about 1mm. Any good metal file will do and you do not need much pressure.

Kalo risiko,
Heinz


PostPosted: Mon Nov 01, 2010 8:37 pm    Post subject: Reply with quote
I had the same problem with my 50/14 MM that I had from Andy.
I had to write him back and he told me to switch the adapters. I had 2 adapters, one chipped the other one not.
It worked with the non chipped adapter.


PostPosted: Mon Nov 01, 2010 9:01 pm    Post subject: Reply with quote
I did not feel like filing my lens.
I think I have found a very simple and non-destructive solution.

The goal anyway was to prevent the lever from traveling.
So, I just blocked its way with a piece of plastic that I cut from my pills packaging:



Seems to work fine Smile


PostPosted: Tue Nov 02, 2010 6:55 am    Post subject: Reply with quote
nkanellopoulos wrote:
The goal anyway was to prevent the lever from traveling. So, I just blocked its way with a piece of plastic that I cut from my pills packaging:


Be careful that that piece of plastic is really secure. If it ends up between the shutter blades somehow, you're screwed.


PostPosted: Tue Nov 02, 2010 7:54 am    Post subject: Reply with quote
nkanellopoulos wrote:
I did not feel like filing my lens.
I think I have found a very simple and non-destructive solution.


Thanks for posting your photo. Hopefully your method holds together (seconding AhamB's concerns), as it is always good to find non-destructive and easily reversible solutions. Cool Once you break out the file, there's no going back!


PostPosted: Tue Nov 02, 2010 9:44 am    Post subject: Reply with quote
Scheimpflug wrote:

Thanks for posting your photo. Hopefully your method holds together (seconding AhamB's concerns), as it is always good to find non-destructive and easily reversible solutions. Cool Once you break out the file, there's no going back!


There is no hole that the piece of plastic could fall into, so there is no danger of foreign bodies entering the lens.
I just hope that this solution will prove reliable in the long term.


PostPosted: Tue Nov 02, 2010 1:43 pm    Post subject: Reply with quote
Had the same problem with 5DII and 3 of my Contax lenses (not my 1.4/50 MM one).

I just used a electric nail filer using a metalic head (my girlfriend's staff ). It only took >2 minutes to file just >0.5mm ....nothing more!!!. Then used an acrylic black paint to cover the edge. Lenses work perfectly on my RTS after this tiny operation so no problem in this department;)

Φιλε Νικο,

Check the inside of your 5dII ... you should have a elliptic scratch in the inside plastic part of the camera's body where the aperture level is still touching Wink

Last edited by Keysersoze27 on Tue Nov 02, 2010 3:01 pm; edited 3 times in total


PostPosted: Tue Nov 02, 2010 1:48 pm    Post subject: Reply with quote
nkanellopoulos wrote:
There is no hole that the piece of plastic could fall into, so there is no danger of foreign bodies entering the lens.


The concern wasn't that the plastic would fall into the lens... rather, that the plastic could fall out of the lens and into the camera. Wink


PostPosted: Tue Nov 02, 2010 2:41 pm    Post subject: Reply with quote
Keysersoze27 wrote:

Check the inside of your 5dII ... you should have a elliptic scratch in the inside plastic part of the lens where the aperture level is still touching Wink

Yes you are right Sad
The damage (scratch) is done now. Do you think I should file it anyway?

I will not cry for a tiny scratch in the inside of a camera that has taken more than 20.000 frames already, and it will keep taking...
I have had 2 injections against tenonditis in my right hand fingers today, and I am still dizzy Smile


PostPosted: Tue Nov 02, 2010 2:52 pm    Post subject: Reply with quote
nkanellopoulos wrote:
Keysersoze27 wrote:

Check the inside of your 5dII ... you should have a elliptic scratch in the inside plastic part of the lens where the aperture level is still touching Wink

Yes you are right Sad
The damage (scratch) is done now. Do you think I should file it anyway?

I will not cry for a tiny scratch in the inside of a camera that has taken more than 20.000 frames already, and it will keep taking...
I have had 2 injections against tenonditis in my right hand fingers today, and I am still dizzy Smile


Well I have it too, before I realise it was the aperture level's fault. Razz It's not such a big deal anyway (it's the anti-reflective finish that was scratched).

If you feel any kind of force resistance when you attach the lens on the 5dII then try to file it as you please. Kαλη αναρρωση με το χερι σου!!!


PostPosted: Tue Nov 02, 2010 2:57 pm    Post subject: Reply with quote
Nikos method works! Thanks much for the tip!
If I knew it before, I would have saved 550 Euros Sad


PostPosted: Fri Nov 26, 2010 3:33 am    Post subject: Reply with quote
hi morfeus. you said when you filed down your contax 50mm, you "Closed the opening of the lever with some plastiline, to avoid metal dust falling inside the lens." i'm not familiar with the term plastiline. do you know if there's another trm for that. and did you cover the channel in which the lever slides? any details you can offer would be appreicated.

thanks


PostPosted: Fri Nov 26, 2010 4:01 am    Post subject: Reply with quote
rhapflan wrote:
i'm not familiar with the term plastiline. do you know if there's another trm for that.


I don't know if there are other words, but I can explain what it is: Plastiline is modeling clay that is mixed with wax, so that it does not dry quickly as normal clay would. I am very familiar with it, because my dad was a sculptor, so plastiline was very common in his studio.


PostPosted: Fri Nov 26, 2010 10:04 am    Post subject: Reply with quote
Orio wrote:
Nikos method works! Thanks much for the tip!
If I knew it before, I would have saved 550 Euros Sad

I also needed to apply this method for the 2/135 AE.
This lens would also not cooperate with most of my adapters.
Post new topic   Reply to topic
Home   Manual Focus Lenses
Page 1 of 1