Will sluggish aperture blades affect my pictures?

Carlb · Jun 25, 2009

I bought a 50mm Olympus OM lens to use on my "extreme conditions" OM 1. The aperture blades are a little sluggish to retract after a shot has been taken but I can't see any oil on the blades so I'm assuming a small spring or some other part is just a bit old and worn. Will this condition have any effect on my pictures? Can it be cheaply fixed?

The seller pointed out this "condition" with the blades in his ad so I knew what I was buying and the lens was priced accordingly. It's basically a sacrificial lens for extreme conditions so it's not crucial that it functions flawlessly, but if it will affect my pictures then I might get it repaired if it's a relatively easy job.

darinwc · Jun 25, 2009

blades that are slow to close will definitely cause problems in bright situations. If they are a bit slow to open, then no that is not a problem. However you have to wonder why they are slow to re-open and perhaps the lag when closing is not as noticeable.

Ian Grant · Jun 25, 2009

If the blades close fast enough there's no problem, sluggish re-opening will have no effect on the exposures. What can be a problem is if the blades don't close consistently to the same aperture, I had a CZJ Pancolor that was inconsistent. Getting the lens repaired may well cost more than another secon=hand lens.

Ian

Steve Smith · Jun 25, 2009

It may also depend on the way the OM stops down the lens. I don't know about OM cameras but some of my M42 bodies stop down the lens on the initial push of the shutter and fire at the end of the shutter movement.

If the OM does this then a short delay between a half push and the final push should ensure the blades are fully stopped down.

Steve.

Rol_Lei Nut · Jun 25, 2009

Even if the blades closing is sluggish, it should have no effect at full aperture (or close to).
For other apertures, you can always manually close them (DOF preview) before shooting.

Test: Open the back of your camera, close your lens to the smallest aperture and look through the back while holding the shutter open with "B". Remember the size of the diaphragm opening. Then, still looking through the back, fire the shutter repeatedly at various speeds and see if the diaphragm opening looks exactly the same size. That will give you an idea of how it might affect your pictures.

ricksplace · Jun 25, 2009

I have a Mamiya Sekor 50/1.4 that I use on a spottie. It stops down OK but opens back up slowly. It works fine. The pics are exposed as they should be. As long as it stops down quickly, you won't notice the delay in opening back up.

eddym · Jun 25, 2009

Have you made any exposures with the camera? If so, do the photos show any evidence of exposure problems?
If not... try it!

Nicholas Lindan · Jun 25, 2009

If the blades are slow you probably have goo/lube somewhere where it isn't supposed to be.

This goo may become thick enough in cold weather to effect closing speed.

John Hermanson · Jun 25, 2009

The migrated oil may be in the rear rings or in the parts of the blade mechanism that you can not see. All those parts must be bone dry to work properly. John

Q.G. · Jun 25, 2009

Rol_Lei Nut said:
Even if the blades closing is sluggish, it should have no effect at full aperture (or close to).

It should indeed.

If you set, say, f/2.8 on an f/2 lens, and the aperture blades don't close fast enough, you end up with (worse case) a full stop overexposure.

But it's true that if you set f/22, the overexposure will be much worse.

Rol_Lei Nut · Jun 25, 2009

Q.G. said:
It should indeed.

If you set, say, f/2.8 on an f/2 lens, and the aperture blades don't close fast enough, you end up with (worse case) a full stop overexposure.

In my experience with sticky apertures, all except the worst cases manage to close at least partly before the shutter opens...

The test I mentioned - observing the aperture with an open back from behind - try that on your favourite sticky aperture lens, you might learn something!

John Koehrer · Jun 25, 2009

Most of the Oly lenses I've serviced for sluggish operation have been from lubericant at the rear or the lens. It's a pretty easy fix though, usually three cross point screws and everything come straight off. There may be a spring connected to the mount and a pin in the body so remove it carefully. Note the alignment before you take it apart it needs to go back the same way it came out. Test the aperture before you put the screws back in to be assured everything is copacetic.

EASmithV · Jun 26, 2009

Will sluggish aperture blades affect my pictures?

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