Stuck Aperture on 50/1.4

[mdcromer]

I just got a lens from ebay for my upcoming Alpha 900.

It's a Minolta 50/1.4

Took some test shots at the camera store. The ones at 1.4 look great while the ones at f/11 are hideously overexposed.

It seems almost certain to me that the aperture is stuck.

Is this something I can fix myself with some disassembly and cleaning and maybe negotiate with the seller for, or should I just return it?

Thanks

[Dr. Harout]

There is a small lever behind the lens, close to the mount from the inner side. Play with it, while looking through the lens. If you notice the leaves of the diaphragm closing and opening, then the 'aperture' is fine. If no, then either the leaves are stuck due to oil or some other malfunction which (both) need a repair.

[Matt_Atkinson]

If your camera has DOF preview like my A100, you can also check it that way. Look through the lens, hold DOF prev button down, whilst adjusting apeture with wheel.

[mdcromer]

Thanks guys.

I actually don't have an alpha yet! Just collecting a few lenses so when I get my 900 in January I have something to shoot with it.

I played with it some more and it looks like the aperture return spring is especially weak. I am able to close it using the lever, but the spring doesn't "push" it hard enough.

I've decided to get it professionally CLA-d if the ebay seller wants to pay for it, or else send it back for a full refund. We'll see what he says tomorrow. . .