Used lens test

[Brentor]

I have just bought another used lens. Physically it is fine and all the controls and buttons work as expected. I very rarely test a lens for optical quality unless it appears to be faulty. I only buy from recognised suppliers who offer a warranty,

Are others more thorough in their testing? If so, how do you test?

 

[ancient_mariner]

I usually check edges and centre against a distant target to see if the lens is decentred, having once bought a very badly decentred lens from another forumite that was effectively useless. Depending on the lens, I'll also check the aperture opens and closes correctly, the focus mechanism is smooth and working properly (in AF) and that it zooms OK. Finally, visual inspection of optics & external surfaces for damage, internally for fungus.

 

[Yardbent]

internally for fungus.

and any traces of oil on the blades

 

[ancient_mariner]

and any traces of oil on the blades

I've only seen that problem with a couple of much older lenses, and it showed up in the photographic tests first with a sticking aperture.

 

[ecniv]

ebay purchases... no fungus and mention of all working ok... even those that have been cleaned...
So far the helios, tair and the mir have a bit of give in the focus... but all work fine

 

[the black fox]

shine torch through lens it will show dust and or fungus

 

[Ed Sutton]

Put lens on camera. Take photos. Look at photos.

 

[Erty]

Check aperture ring, focus ring and zoom run smooth. Check elements for scratches (particularly the rear one).

 

[sk66]

I do a basic decentering test on every new-to-me lens.

Testing for a Decentered Lens: an Old Technique Gets a Makeover

What is Decentering and What Does it Do? Strictly speaking, decentering would involve one or more of the lens elements being off of the central axis of the lens. This would prevent the curved surfaces of the lens from bending the light properly. In severe cases it could result in halos or...

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