Lens advice?

I have a sony a100 (alpha) dslr and i was wondering if these lens's are any good in general

http://cgi.ebay.co.uk/500-1000-1600mm-Le...

They seems to have long rang zoom on it and i do wild life photography and its hard to get up close to animals in the wild without them running of so i just wondering which lens would be good for the job?

If i'm reading the ad right you are just getting a 500mm lens at 8.0 f-stop and then they are trying to sell you on the idea of a 2x multiplying tube to get it to 1000mm and with your camera multiplier it then becomes 1600mm.... Well first off the multiplying tube will also cut your 8.0 f-stop down to something more like 16.0... so that hurts a lot... secondly the lens is manual focus, most DSLRs don't have split screen in the view finder so focusing in anything less than bright light is more guess than you would expect.... Frankly you should pass.

Go look for a minolta AF lens in the 300mm range you can find them on ebay fairly cheap and with the cameras multiplier will basically turn it into a 450mm lens... I've used a 300mm on my nikon and gotten very good result of wildlife, so don't think you need some mega lens that only really makes sense for sports photographers shooting surfers... you can probably get by with much less lens. The key is to get good glass in the lens and depending on the camera's viewfinder - auto focus.

These are cheap lenses and the main issue for you as a widllife photographer is the relatively small maximum aperture (f8), which means you need to counterbalance it with a longer shutter speed (no wider aperture being available). So this is not a very good solution if you need to hand hold the camera, work in low light, or freeze the movement of moving subjects... I suspect you will soon run up against its limitations.

Good luck!

Don't do it. These are cheap lenses that will yield distorted results. You have a great camera but the lens is crucial. You could look for lenses made by Sony/Minolta/Konica that will fit your lens mount. Used is fine. BTW get a good tripod if you want to wildlife photography with a long telephoto.

Don't waste your money. Heed the advice of the person who suggested a Minolta AF 300mm or 400mm from ebay.