Originally Posted by spectrumphoto
Its the glass that counts. Fixed f-stop lenses are ALWAYS going to be better than floating f-stop lenses. Forget the amount of zoom a lens has, go for a lens that has a fixed f2.8 stop and your image quality will improve dramatically as these lenses have a greater surface area on the front element.
I think you might need to reword that. By simply having a lens with a fixed aperture does not automatically give you better quality.
All the fixed aperture lenses will do vs a floating aperture lens is the fact you will lose x amounts of stops worth of light. It will help yield a faster shutter speed but still can result in bad IQ.