A camera is only as good as the lump of glass on the front of it.
Good lenses are crucial to good photography.
There are thousands of lenses for sale on ebay.
So how can you tell the peaches from the lemons?
Hopefully, this guide will help you to make an informed choice.
It is not my intention to discuss the relative merits of prime lenses verses zoom lenses, or independent lens makers verses major camera makers. There is a ton of such info on the internet.
This is just a simple guide to buying a lens on ebay.
A lens is just a tube with some glass and a few moving parts inside it. There's not a lot that can be wrong - is there?
Actually there is!
A lens is a highly complex piece of engineering - made from fragile components - and very easily damaged. Most lenses will contain several precision made glass elements, and a diaphragm, made from wafer-thin metal blades. There will also be controls on the outside of the tube, and various pins and fittings for attaching the lens to the camera.
All of these can (and do) go wrong!
Before you buy a lens, you should know the following...
1. Are there any scratches on the glass? -Surprisingly, some scratches can be ignored - a very small mark (1-2mm) at the edge of the front element will not ruin your pics. But generally speaking, a scratched lens is a bad idea. Scratches may not show up on the seller's ebay pictures - so ask him!
2. Is there anything inside that shouldn't be there?
Most older lenses will contain some dust. If it is just a few specks, and they are not clustered together, you should be ok. Any more than that, or any clumps of dust, and you could have problems. Ask the seller about dust. If it's bad - Walk away!
Fungus is a serious problem! Older lenses are prone to it - especially if they have been stored in a damp environment. If the lens you are looking at has fungus inside - walk away! You can recognise fungus quite easily - it grows across the glass in fine strands - spreading out like the branches of a tiny tree. The seller may tell you that it is just a small amount, and that it does not affect performance of the lens - and he may be telling the truth. But walk away anyhow! The fungus will grow worse, and even if you are willing to pay for the lens to be professionally cleaned, you may not solve the problem. Fungus can etch its way into the glass, so even when it is removed it will leave its mark!
Sometimes pieces of the lens may break off inside, and rattle around. If the lens you are looking at has any such objects inside, or anything else that shouldn't be there - Walk away!
3. Is any part of the lens damaged?
Quite often you will see lenses for sale with "Minor damage to the filter ring." - Walk away! It may be minor damage - but it is a sure sign that the lens has been dropped - and that could mean internal injuries! The same applies to any external damage. Ask the seller if the lens has any dings, dents or gouges, and if he says yes - Walk away! Also ask if the pins and fittings on the lens-mount are undamaged. Bent pins and buckled mounts are best avoided. General wear and tear (ie worn-off paint) is not necessarily a sign of a damaged lens - but it is a fair indication that the lens has not been cherished! Be careful!
4. Does the Diaphragm open and close properly?
The diaphragm is made from several wafer-thin metal blades. It is designed to open and close to set the lens aperture. A common fault in older lenses is oil on the diaphragm blades. Lenses have moving parts - some of which need lubrication - but if any of that oil or grease gets onto the diaphragm blades, they will stick. The same applies to grit - one grain of sand can jam a diaphragm. Oil (and grit) can be cleaned off - but it means dismantling the lens and would only be worth the cost if the lens is a very good one.
On most lenses it is easy to check the diaphragm. There will be a pin or a lever on the back of the lens, which activates the blades. They should open and close in the blink of an eye - with no hesitation. Ask the seller if he has checked them. If the blades are sluggish - be careful! You could end up with a repair bill!
5. Do the focus and the zoom operate smoothly?The focus ring should move through its range with no snags or stiff areas. If it is a zoom lens, the zoom control should do likewise. Good controls feel firm and positive - not overly tight but not sloppy. Ask the seller about the focus and zoom.
6. Are the aperture adjustments crisp and snappy?
The aperture ring should click neatly from stop to stop, again with no overly tight spots and no sloppiness. Ask the seller if this is the case. On a less expensive lens, as long as the correct aperture can be selected - a certain amount of slackness in the ring is not a serious problem. But if the ring moves without any clicks - it is a sign of irrepairable wear.
7. Will the seller refund your money?
Unless you are buying the lens for spares or repair - steer well clear of any seller with a "No returns" policy. There are plenty of sellers on ebay who will reund your money if your purchase turns out to be a dud.
Ebay is a wonderful place - the greatest shop window in the world. I am proud to be an ebay seller, and I don't think there is any need for buyers to get ripped off!
Having said that, a seller with a bad lens is not necessarily an unscrupulous villian! He may not be totally aware of what he is selling. He may not be an expert, or he may be selling so many items that some do not receive proper inspection.
Unless a seller lies to you, don't blame him for selling you a bad lens. It is up to you, the buyer to know what you are getting.
So ask questions!
If you have any questions for me, please feel free to contact me via ebay messages. I will do my best to answer - or to point you in the direction of someone else who can.
And please visit my ebay shop
Many thanks for reading my guide.
I hope it has been of some use.