Check list - Buying used lens

<p>Hi All,<br /> I am trying to buy used 24-70 2.8 AFS. I never bought a used lens. Please suggest me any check points,warning signs or suggestions ( Other than basic cosmetic checks) I need to follow.<br /> Appreciate your help.<br /> PS: Also trying to get used SB700 along with above lens. Any suggestion in this regards will be help.<br /> Thanks</p>

<p>If you type "buying used lens" into the search box you will find lots of helpful hints and excellent advice from many previous threads on this topic.</p>

<p>I was referencing Canon - oops!</p>

<p>Suggestions:<br>

- Obviously check for scratches, fungus, etc, as commonsense would dictate.<br>

- Be sure the zoom ring does not bind. If it does, there might have been impact damage.<br>

- Mount on a camera and test autofocus; listen for any squeals in the AF-s motor.<br>

- Take a test frame at around f/4-5.6, and check all four corners for quality. If one or more corners is noticeably degraded in comparison to the other corners, there might be some de-centering. </p>

<p>A list somewhat similar to the above:<br /> 1. Indoors, use a flashlight to look for scratches on the front and rear elements.<br /> 2.Indoors, use a flashlight to look for fungus on the glass. It can look cloudy or blotchy or like a spider web.<br /> 3. Check to see if the filter ring is dented. If you have any doubt, try putting on a filter.<br /> 4. If the lens comes with a hood, look for damage. Hoods that are permanently attached to the lens sometimes won't slide in and out properly. If a metal hood has a dent, it's a good indication that the lens was dropped. If the lens is supposed to come with a detachable hood, check that it's there and mounts properly.<br /> 5. Check that all the controls on the lens work properly: zoom, aperture, change from AF to manual, etc.<br /> 6. Most important: Mount a body on a tripod and shoot through the lens. Examine the photos for sharpness, focus and exposure accuracy.<br /> 7. Look at the lens barrel for scratches, etc.<br /> BTW, squeals from an AF-S motor or focusing mechanism should not necessarily disqualify a lens.</p>

<p>Check for a sticky aperture by pulling the aperture lever and then releasing it on the lens. Check that the aperture opens and closes as quickly as you release it.</p>

<p>Also check the filter ring by screwing in a filter. If the lens has been dropped or damaged the filter ring can be damaged. This is more common on metal than plastic though.</p>

<p>Looks like the main problem with this lens is about the zooming barrel action. The front barrel retract from 24 to 50, and then extends up to 70.</p>

<p>In horizontal position, when you turn the zoom ring, a good sample should show a smooth action along the whole range, without any kind of resistance. It should be smooth and "almost" perfectly continuous. Upside up and specially upside down there is some resistance to the zooming action, it is normal. A friction noise (or even a squeak due to the barrel friction) is normal, if you spin the lens it should dissapear.</p>

<p>I suspect this lens is not strong enough to support a camera mounted on it and left upside down (directly over the front barrel of the lens). My guess is that if the lens has been used and stored with the hood in place, there is a minimal risk for the zooming helicoids. But if as I have read many times, the user is not fond of using hoods, this particular lens, sooner or later, could be damaged. (It is just a guess, I don`t have any scientifical evidence to prove this idea).</p>

Bring a filter and test mount it to be sure the threads are OK.

<p>0. Check it's US lens. Nikon USA wont service any import/gray market lens even if you beg them with money<br>

1. check the glass for scratch or imperfection. Ultimately all lenses will be sold off, imperfections to the optics are very hard to sell<br>

2. Check the inside elements for fungus. Primes are generally easier to clean (except super telephotos) but zooms can be pricey. I wouldnt worry too much about dust though, even though they do suggest the amount of use<br>

3. Use AF tracking and see if the AF motor is noisy. Again another $200-300 repair easy if it breaks<br>

4. 24-70 tends to have sticky zoom ring due to lack of lubrication.<br>

5. Check the focus ring for noisy sound, even if you dont manual focus. Might have indications of sand damage or other internal damage if it's noisy and rough.<br>

6. If the zoom and focus rubbers are loose, no big deal. Cheap to replace yourself, order from Nikon website.<br>

7. Check the aperture is not sticky and free from oil by opening and closing it<br>

8. Check the filter thread is not damaged (signs of drop) by putting in a filter<br>

9. If you have purchase receipt within 5 years, great. Nikon will fix anything within that period unless the user abuse is so obvious that they will deny the liability.<br>

10. Scratches and marks can indicate signs of wear, but they might not suggest it is a bad lens necessarily.</p>

<p>Thanks all for your help <br>

hemant</p>