Quote Originally Posted by Rol_Lei Nut View Post
While in principle I agree that that all optical design is a tradeoff, I disagree with your implication that that means that there are no fast lenses out there with great all-round performance.

Using the same Nikkor 35mm f/2.0 AIS as an example, while a fine lens in its own right, I have 35mm lenses which:
1) are sharper wide open
2) vignette less
3) distort less
4) flare less
5) have more or less the same size & weight
Admittedly those "better" lenses were once much more expensive when new. But the tradeoffs can be much less than you seem to imply.

That said, I'm a fan of very compact and corrected slow lenses as well...

I've never ever heard of lenses expressly being designed to be less sharp, unless you're talking about portrait and/or "soft" lenses
The tradeoffs inherent to the physics of optics are usually mitigated by increasing the size of elements across the axis, added elements, better coatings, etc. A major tradeoff is mass. For many brands a 50/2 is almost 30% less weight than a 50/1.4, and usually less than half the price, with both having near equal sharpness and distortion at f/2.8.

I had a Zeiss 50 for my Pentax system. It had superb center sharpness and resolution and great colour rendering. Its edge distortions were noticeable until 2 stops down from max. It was also worth 2.5x more than a Pentax brand equivalent but in real life photos, it was hard to see the differences. It had great all around performance, but there was a flaw based on the unavoidable optical physics limitations. I could get the same performance out of much less expensive glass at the expense of 1-stop.

I therefore concluded biggest discrepancy is price vs. noticeable distortion in real life photos.