[RollsUp]

What does one need to look for when buying used lenses?
Obviously scratches and dents.
Dust particles, how much dust does it take to affect IQ?
Haze, I've read that when the lens is viewed with a flashlight it would look somewhat foggy like?
Oil on the aperture blades, what does it look like and how does oil get on the blades?
Fungus, what does it look like?
Anything else I missed?

If I find any manual lenses when I'm at Anchorage, AK I would like to know what I need to watch out for.

Thanks.

[pasipasi]

Try how the aperture, focus and zoom rings work. Dust particles might not be visible in the pics you take, but they may be vulnerable to shooting against light. If possible, mount the lens and shoot against a wall and see if the picture is sharp in edges and corners.

[deejjjaaaa]

http://images.google.com/images?hl=en&q=+fungus +lens

[Nesster]

Try the lever in the mount that stops the lens down. The aperture should close down fast, and open back up. If the mechanism is slow, the cause can be many things, but the result is not good for taking photographs. Unless you plan to spend your time or $$ getting it fixed, pass these by.

Imperfections in the front glass matter less than anything on the rear element, but can be used as a bargaining point.

Look for any bent filter ring. Again, not the end of the world, but should you choose to, it can be a bargaining point.

As pasipasi says, if you can, mount the lens and test it with the camera - does it focus to infinity, are there any strange behaviors with the zoom etc.

[stevebrot]

Use a bright flashlight to view the inside of the lens. Dirt, oil, element separation, and fungus become much more visible. Be particularly aware that fungus can be hard to detect except in oblique light. Avoid fungus at all costs since it generally gets worse and can be difficult, if not impossible to remove.

As stated previously, any issue with the rear element is much more critical than the front. Even a small spot of fungus toward the center of the inner surface of the rear element can make the lens soft overall.

Steve

[Shashinki]

#1 rule of buying used lenses is: "checking if the lens is actually good in the first place so that you don't end up with a crappy Centon or Rokinon lens or something similar"

[heatherslightbox]

If you're going to buy used from a dealer, then make sure you buy from a reputable seller who has a good return policy just in case you get it and you find something is wrong. From personal experience, I can highly recommend KEH Camera: Used Cameras, Digital Cameras, Film Cameras, Laptop Computers and More.. I once bought a lens from them and when I got it, I noticed that it has a horrible case of zoom creep, so they took it back, no problems. They also have very high standards as to how they rate their lenses, so if the lens you want is rated in "Excellent" condition, it will most definitely be in "Excellent" condition.

HTH,
Heather

[RollsUp]

Thanks all. I'll keep your tips in mind when looking at lenses.
@Nesster, what lever are you talking about? Is it the one on the older Takumar/Super Takumar lenses?