If, like me, you’ve just bought a digital SLR camera then you may well have picked one that can use older film lenses. First, a caveat: Not all can do this with equal success. You may get some slightly unpredictable results. In my experience Pentax are fine, but I can’t comment on others.
With that out of the way, some advice on buying lenses. Older lenses can suffer from dust or worse fungus inside the lens. Check for both, and don’t pay top price for a lens with either. I would personally avoid any fungus-afflicted lenses as there would presumably be a risk of transferring fungal spores to the mechanism of the camera.
Dust, providing that it is not in ridiculous quantities, doesn’t affect image quality hugely. You’re unlikely to see noticeable blemishes in your photos but you may notice a loss of sharpness. If the lens is cheap, then it’s probably worth a go.
Never be tempted to try to remove dust by dismantling the lens. Unless you’re a trained technician with a clean room then you will make things worse rather than better!
Obviously you should check that the focus, zoom, and aperture rings move smoothly. It can also be worth checking for excessive oil or grease on the aperture blades.
If you buy your lens from a good camera shop then you shouldn’t have any trouble with these. However, buying online can be a bit of a lottery. Some sellers will provide plenty of photos and assurances that the lens is dust and fungus free. In these cases you should have little trouble with gaining a refund if the item is not as advertised. If you’re interested in 28-80mm or similar zooms, then try searching for film SLRs that are being sold with one. The camera is usually worth next to nothing in an internet auction, so you can buy it solely for the lens.
Do your research before buying. Some lenses don’t attract much interest at all, quite often because another similar model is a far better performer for similar money. If you can’t find any information on a lens then caution is advised. It may be great, but then again it may be a complete dog. There is, however, considerable entertainment to be had from buying the cheapest lens you can find and playing around with it. While it won’t be useful for serious photography any strange effects it has could well result in some interesting images.
