Tons of very enlightening stuff in this comment.Scarodactyl wrote: ↑Tue Dec 14, 2021 9:18 pmIn photomicrography we're almost always on or near the cutting edge of diffraction, and cropping a bunch of the image is not particularly helpful on that front. For some subjects it doesn't matter--diatoms and bacteria and such are the size they are and you're often going to be cropping anyway even with 100x mag. But just by the numbers if you have an objective with a wide 25mm fn, then slap on a 2.5x magnification factor on aps-c with a 27mm diagonal your effective field number ends up being more like 11mm. All your objectives are essentially acting like they have more than twice the magnification but the same NA on camera. With a 20x/0.75 that might still be pretty workable, but with a 40x/0.75 the picture is different.
If you're imaging singular subjects and only care about the center of the fov anyway that's really not a problem. But if a wider field helps it's a whole lot nicer be able to capture the field of a 20x objective with your higher resolution 20x objective rather than having to use your 10x. And just from a monetary point of view, a lot of what you pay for with many high end objectives is better performance over a wider field. If you crop it heavily you're losing a lot of that benefit.
That said I mostly work with gems and minerals, so there are lots of subjects and compositions across a wide magnification range. I also mostly use longer working distance objectives so diffraction is a particular concern if I push things too far.
I think first of all I would say that I'm a microscopy enthusiast first and a photomicroscopy enthusiast second. For me, it's personally seeing cool, excellent scenes through the eyepieces that is of foremost concern. Relaying those images to others is secondary - I'd rather the audience get their own microscopes and experience the same.
And then of course I'm also primarily into microbes - so wide fields of view are secondary to nice, highly resolved images of little critters ~200um or smaller. I am particularly fond of my high NA 10x and 20x objectives because of how much flexibility they give me for zooming and cropping. As you've said, your application has very different requirements.
So yeah, I can't disagree with anything you've said - it all makes total sense. It's really helpful to read stuff like this because it helps me understand my internal biases. I think it's worth pointing out nuances like this since threads on this forum get read years and years down the line completely out of the original context - at least I do that
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