600mm f/11 or 800mm f/11 - which one would you buy?

BirdShooter7 wrote:

Thanks for the articles though it would be nice to have a more direct answer to the question.

Sorry; if there were a quick comprehensive answer I would have provided it.

I got the impression from your comments that the pupil magnification had some important implication on the output from these lenses.

There's no real practical implication unless you take things like DOF calculations seriously. Those for example are far less precise than you might think. And two lenses that you might expect to perform identically might very well not.

I’m not an optics expert by any means but the little that I had read on that issue seemed to suggest that pupil magnification doesn’t typically have a significant impact on the optical properties of camera lenses. For this reason, your seeming to suggest otherwise peeked my interest.

It's an important characteristic but from a photographers perspective less so than sharpness, correction for aberrations, etc.
Close-up photography is one area where in a technical sense pupil magnification becomes pretty important whether you realize it or not.

If there is something important to the image making process that I can learn from a better understanding of this then I definitely want to know more. If the main benefit is to just understand optics better for the sake of knowledge then I probably have more pressing things to use my time on though a better understanding of optics would be a nice luxury.

There's no urgency. I hope you'll get around to understanding the topic better at some point in the future.

So was there something specific you had in mind when you made your comment?

A lot of people visit the fora. For some of the more technically inclined my comment was intended to get them to question whether they fully understand what they're saying. Many people are parroting conventional "wisdom" that doesn't really represent reality. Except for misunderstanding the fundamentals we often get away with it.