Originally Posted by tonton
A "prime" lens does not mean a branded lens (Canon, Nikon, Sony, etc.) as it seems you're implying here.
A prime lens means a non-zoom lens. Like a 50mm lens, or 35mm or 100mm macro, etc. They are all primes, whether made by Nikon, Sigma, Carl Zeiss or Sears (yes, there were Sears lenses long ago).
Still, the Sigma zooms, except a few of the APOs generally still have very poor image quality, though the build quality is great. There was a $50 plastic Vivitar macro (the "plastic fantastic") that was famous for horrible build quality and exceptional performance. Also remember that Carl Zeiss is a 3rd party.
The point is you can't make any judgemnt on whether a branded lens or third-party lens will perform well based on that criterion alone. You need to do the research to find the good ones.
This week seems to be my week of explaining myself.
Ok, what I should have said, as the term is used in the photo industry, is that a Canon, Nikon, etc are considered to be prime lens manufacturers. That means that they make the "official" lenses for their own systems.
I'm aware that a "prime lens" is the lens that ships with the camera. A prime lens now does mean a zoom lens, if it ships with the camera. All D-SLRs come with prime lensesthe cheap zooms that are almost being given away with them.
Expressions evolve with the times. When I started out, no pro would ever use a zoom. Now, except for exteme wides and tele's, almost all do.
If you have read the hundreds of reviews published in magazines such as the venerable Popular Photography, as well as those on the better web sites, you would find that you are wrong in your assertions. Many third party lenses are very good indeed!
The prime manufacturers lenses are still better made, and in general, are somewhat better performing, but the distance between the two has narrowed considerably. Many of my clients used third party lenses.
APO in the name doesn't mean better quality, even though manufacturers would like to have you think it does. What APO means is that it has a flat field, with all three colors focussed in that plain, rather than only two. But, it doesn't mean that the lens is sharp, contrasty (APO lenses traditionally, except for the four element process lenses, have not been), and free of other distortions, such as barrel, pincushion, light falloff, etc. I still have two of my old Red Dot Artars, great lenses, but for 4 x 5, and slow.
The point is that everything has gotten so much better, that normal size output looks about equal no matter what equipment it is taken on.
You really have to get to a 14x17 print size to even begin to notice actual differences. This was my business for many years. I've looked at many thousands of pro prints.
Carl Zeiss is a third party, of course. But it's not likely that readers here will be buying their lenses, which cost much more than even the lenses of Canon and Nikon. They are in the range of Leica lenses. The range is very small as well. The wides are considered to be some of the finest lenses made today.