Selling lenses

I have four, possibly five lenses that I'm planning to sell. I'll probably offer them here first, but whether here or on eBay, I want to make sure that I describe them as honestly as possible.

I've noticed many listings describe lenses as having

... no oil on the iris blades
... no fungus.

What should I look for to establish a lens' condition in these respects?

And why is the absence of oil important?

here is what I do, if others have better suggestions then I'm open to them (like you I always want to describe my items fairly)

open up the aperture and closely inspect the lens elements from both ends of the lens, holding it up to some sort of light source will help you to determine if there is any fungus or other nastys in there. A little dust is normal on an old lens but I always make sure I mention it anyway.

close down the aperture and inspect the blades from both ends. Oil on the blades will be obvious if it is there. I also gently work the aperture stop down actuator to verify that the aperture blades move smoothly and without resistance.

It's always worth checking the focus ring works too, obvious I know but I was sold a macro lens a couple of months ago which was perfect in every way except that the focus ring sticks at 1:2 and 1:10, making it basically unusable.

The slightest hint of oil on the aperture blades will cause them to stick together and become sluggish in operation. This will cause incorrect stop-down and exposure errors.

What lenses?

I checked my old A 50mm F1.7 and A 24-50mm F4 for fungi and defects yesterday and saw just a little dust. This made me rather happy as they've not been used in some years.

I need to find myself a 49mm reverse coupler and a 52-49mm step down ring though. Any suggestions as to where to get these?

The best place for reversing rings & suchlike is www.srbfilm.co.uk

Jonathan

eBay is great for little bits and pieces like that - from UK and Hong Kong sellers.

See http://tinyurl.com/3bmgew

and http://tinyurl.com/3xs25s

Well I haven't taken any pictures of them yet but the list will definitely include the following:

SMC Pentax-M 1:3.5 135 mm
SMC Pentax-M 1:4 200 mm
Pentax A 1:3.5-4.5 28-80
Sigma 600mm F8 Mirror lens

I also have a Sigma 28-200 F4-5.6 that I'll probably very rarely use now (since I now have a Pentax 28-200 FA), that I ought to let go, but it's come with me on many memorable trips and given fantastic service, so I'll probably keep it for old times' sake.

I'm also in imminent danger of acquiring a Pentax 400mm prime, so its Sigma equivalent in beautiful condition, acquired recently from a forum member, should probably also find a new home.

Definitely the first four though. I'll be inspecting them carefully before I make any formal claims, but they're all in good condition, optically and cosmetically, AFAIK.

Damn... I was hoping you'd have a spare A or M f1.2 50mm Really want to get my hands on one.