What do I need to watch out for buying a 2nd hand lens?

[Boofhead]

I have just bought a Canon 10-22mm lens on Ebay and would like to know what things I should be checking when I go to pick it up? Any advice would be appreciated.

[simonw]

Not sure if you know, but buying on eBay means you are now obliged to pay for the item. I have sold things before and had people come over because they just want to look. Obviously if the item is not as described, a different story

[Boofhead]

Thanks Simon, yep, I have bought a bit (Cheryl, my wife, would say a LOT, lol) on Ebay. I am more than happy to proceed if the lens is as described "in excellent condition, only taken a couple of shots". I would just like to know what to look for as I think it would be easier to dispute the condition before I have taken it home.

[ricktas]

take the lens cap off, and the back cap, get a torch and shine through the lens. Look for spidery looking 'veins'. If these exist, keep the lens away from your other gear, as it has fungus. You can get it professionally cleaned (at a $$) to remove the fungus, but I would make a claim against the seller if it does have fungus, cause it is basically as useful as a vegemite jar.

[Boofhead]

Thanks Rick, great advice as I would not have thought to take a torch with me. Reckon it would be best to do this before I put the lens on my camera.

[ricktas]

Thanks Rick, great advice as I would not have thought to take a torch with me. Reckon it would be best to do this before I put the lens on my camera.

Definitely. Fungus spores are tiny. Putting a fungus filled lens on your camera is sure to transmit some of those spores to your camera body, and then into the next lens you put on the camera....

[dche5390]

Test the AF. Test the MF. Then test whether it blends. Ok, perhaps not the last part.

[Boofhead]

Test the AF. Test the MF. Then test whether it blends. Ok, perhaps not the last part.

LOL, thanks very much!

[Cindersfella]

Check compatibility with your existing equipment, scratches on the lens's no external damage and last of all that's its true to condition as described experience is a good teacher, last thing Buyer beware is all I can say.

[Wayne]

In addition to the above, ensure the aperture blades move freely and open and close fully on the body of the camera. Ensure the zoom and focus rings move full rotation and do so smoothly. Check the mount for brassing, this can tell you how much it may have been taken on/off a body. Take a ruler, and check it focuses where the focus point lies, not front/back focusing.

[Boofhead]

In addition to the above, ensure the aperture blades move freely and open and close fully on the body of the camera. Ensure the zoom and focus rings move full rotation and do so smoothly. Check the mount for brassing, this can tell you how much it may have been taken on/off a body. Take a ruler, and check it focuses where the focus point lies, not front/back focusing.

Thanks for the advice Wayne, would you mind explaining how to check that it focuses where the focus point lies?

[Wayne]

Basically, use the ruler standing on it's edge and about 70 deg across the focal plane, then using the smallest aperture with the lens at just over minimum focusing distance, aim at a defined point on the ruler with a single focus point, and snap a shot. The resulting pic should show the focus is sharp where you were aiming the focus point, and should show the fore/background out of focus. If say you aim at the 15cm mark, and the resulting pic shows that at 15cm the ruler is blurred, but say 16cm is sharp, then you have a back focus issue, and vice versa for a front focus issue.

See my attached image.

[Boofhead]

Basically, use the ruler standing on it's edge and about 70 deg across the focal plane, then using the smallest aperture with the lens at just over minimum focusing distance, aim at a defined point on the ruler with a single focus point, and snap a shot. The resulting pic should show the focus is sharp where you were aiming the focus point, and should show the fore/background out of focus. If say you aim at the 15cm mark, and the resulting pic shows that at 15cm the ruler is blurred, but say 16cm is sharp, then you have a back focus issue, and vice versa for a front focus issue.

See my attached image.

Very well described Wayne, thank you very much for your time and efforts to explain this to me.

[Boofhead]

I picked up my lens today and it appears to be in excellent condition, passed all the tests described to the best of my ability. All the advice given is very much appreciated, thank you all.