This was inspired by sixtsix in the "picking a lens" thread. I know the first time I bought a used lens I had the same question so hopefully this will help others in the future.

I'm still a semi noob at this so I've added everything can think of. Please feel free to offer more suggestions. Some of these come from being burned so make sure you pay attention when looking at a potential purchase.


I would check several things...

Diaphragm:
Flick the aperture control on the back of the lens to make sure the diaphragm opens and closes smoothly and quickly with no sticking

Shine a light on the diaphragm blades and see if they have any oil on them. You want them to have no (preferably) or very little oil on them.

Glass:
Of course look for scratches on the glass, minor scratches may not have any effect on photos taken at wide aperture. If they are significant they will become obvious in your photos at small apertures.

Check through the back of the lens for fungus growing on the glass.

Also check for cracks, just make sure you bring some light source with you while checking out a lens.

Body:
Check for obvious signs of drops and bumps.

Make sure the lens has both lens caps with it. Usually if it doesn't then the owner probably stored it that way and may not take very good care of his/her stuff.

Check out the filter ring threads and make sure they haven't been cross threaded or destroyed from a drop. Also visually check it for roundness. Generally if the lens has been bumped or dropped signs will be obvious on the filter ring.

Check for zoom creep... hold the lens downward and see if the lens' zoom slides out. This may or may not bother you but to me it gets really annoying if my lens slides out every time I let my camera hang.




You're also going to want to bring your camera so you can check to make sure the motor and autofocus are both functional. Check your histogram and make sure it reasonably reflects the light conditions in which you are shooting. If you can only view your test photo on you camera, zoom in and pan around to check for sharpness.


Ben, if this doesn't belong here or if don't want it around feel free to do with what you want.

looks great to me.

Originally Posted by jblaze5779

This was inspired by sixtsix in the "picking a lens" thread. I know the first time I bought a used lens I had the same question so hopefully this will help others in the future.

I'm still a semi noob at this so I've added everything can think of. Please feel free to offer more suggestions. Some of these come from being burned so make sure you pay attention when looking at a potential purchase.


I would check several things...

Diaphragm:
Flick the aperture control on the back of the lens to make sure the diaphragm opens and closes smoothly and quickly with no sticking

Shine a light on the diaphragm blades and see if they have any oil on them

Glass:
Of course look for scratches on the glass, minor scratches may not have any effect on photos taken at wide aperture. If they are significant they will become obvious in your photos at small apertures.

Check through the back of the lens for fungus growing on the glass.

Also check for cracks, just make sure you bring some light source with you while checking out a lens.

Body:
Check for obvious signs of drops and bumps.

Make sure the lens has both lens caps with it. Usually if it doesn't then the owner probably stored it that way and may not take very good care of his/her stuff.

Check out the filter ring threads and make sure they haven't been cross threaded or destroyed from a drop. Also visually check it for roundness. Generally if the lens has been bumped or dropped signs will be obvious on the filter ring.

Check for zoom creep... hold the lens downward and see if the lens' zoom slides out. This may or may not bother you but to me it gets really annoying if my lens slides out every time I let my camera hang.




You're also going to want to bring your camera so you can check to make sure the motor and autofocus are both functional. Check your histogram and make sure it reasonably reflects the light conditions in which you are shooting. If you can only view your test photo on you camera, zoom in and pan around to check for sharpness.


Ben, if this doesn't belong here or if don't want it around feel free to do with what you want.

can you clarify? do you want to see oil or not?

You do not want to see oil.

One of my lens has a little on the aperture diaphragm but it hasn't effected the lens yet. A lot of oil will hinder the snappiness of the diaphragm.

Just make sure it isn't excessive.

Originally Posted by jblaze5779

You do not want to see oil.

One of my lens has a little on the aperture diaphragm but it hasn't effected the lens yet. A lot of oil will hinder the snappiness of the diaphragm.

Just make sure it isn't excessive.

cool, thanks i'll keep that in mind.

Hey I found an awesome used lens buying guide on ebay... it has pics and everything.

http://reviews.ebay.com/How-To-Detec...AT:-1:SEARCH:1

that's awesome, thanks for the link.