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Dufflespank
Tinkerer
Username: Dufflespank
Post Number: 3
Registered: 05-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, July 15, 2008 - 10:30 am: | 
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I just picked up a cool 28mm Vivitar FD from the swap meet for a decent price. Anyways, I loaded it on both my a1 and my ae1, and when the shutter button was depressed, the shutter would open and not close. The shutter would be stuck open unless the stopped down button was pressed, or if the lens was removed. I checked the lens out closely, and I realized that the bayonet was slightly bent, thus causing the bayonet to not spring back with enough force. I bent it back into place as best I could and now it returns into place with more force.
So, the shutter now performs properly, however, the iris is slow to return to its fully open state after the shutter has closed. I tested some different shutter speeds and it seems like the iris stays static while the shutter is open, which is normal. However, I'm worried about the iris not returning to its wide open state quickly enough.
In your opinion, is this lens okay to use? |
Glenn
Tinkerer
Username: Glenn
Post Number: 380
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, July 15, 2008 - 06:49 pm: |
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It seems that this lens has suffered some mechanical damage - due perhaps to being dropped? Of course the slow iris could be due to oil contamination.
One of the best items to check FD lens operation is the Canon Macro Hood. If you cannot lay your hands on one, cut the end out of the correct type of rear lens cap for this lens. I guess this is a breech ring FD lens? Fit the modified rear cap - then you will be able to operate the iris mechanism, in the correct manner with your fingers. This will allow you to check if the operating levers/mechanism has been damaged, and is thus stiff.
From memory; you should be able to correct any damage to the actuating levers, from the rear of the lens. |
Dufflespank
Tinkerer
Username: Dufflespank
Post Number: 4
Registered: 05-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 17, 2008 - 03:17 pm: |
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So, would you use it? Once again, the iris opens up and stays open for the duration of the shot, so I don't think that the film is being exposed incorrectly. Am I thinking wrong?
Is there any information out there that might walk me through a repair? I'm on vacation right now, so I won't be fixing it until I get back home, but I would like to know if it is usable, because I'm sure to encounter some neat sights within the next two weeks! |
Glenn
Tinkerer
Username: Glenn
Post Number: 382
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, July 18, 2008 - 03:06 pm: |
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Your description of iris operation in the second post seems to be in variance to your original description.
Does the lens stop down when you release the shutter? If it does and the return to fully open - after the exposure - is slow, the lens should be usable. You should note that the exposures may not be spot on - this depends on the lens stopping down to the correct aperture and if damaged this may not happen.
Obviously if the lens is not stopping down just prior to exposure, you have a problem and lens is not usable in AE function.
You may be able to use the lens in none AE manual mode. Most FD lenses will function correctly in manual mode when the iris is 'sticky'.
Your best bet is to buy a cheap film and run a few test exposures - I am sure you will be able to find a local processor, unless you are vacationing in some exotic or remote places! |
Dufflespank
Tinkerer
Username: Dufflespank
Post Number: 5
Registered: 05-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, July 18, 2008 - 04:49 pm: |
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Yes, the iris completes its primary task (to the best of my knowledge), however it is just kind of slow to return to its fully open state after all of the exposing is done, it sort of slowly retracts; you can see it just by looking into the lens. It does this for all apertures.
I have been shooting in shutter priority AE, and hopefully that hasn't been a bad idea. I also brought my ae-1 on the trip, which currently has no film, and I've tested the lens on AE mode with the ae-1, and it appears that the camera can successfully control the aperture from AE mode, so I'm fairly certain my shots from the trip so far won't be toast.
When I get home, I'd really like to repair this thing, can anyone point me in the right direction in terms of repair literature or online DIY's? I can probably diagnose the problem once I've done some slight dissection, but are there any repair manuals that will guide me through the disassembly process? Thanks a whole lot for your help! |
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