Judging high-NA infinity-corrected objectives

[JohnyM]

In the very near future I will be able to compare the Nikon 20/0.75 with a 2X magnification changer against a native 40/0.75

I do have Microphot with mag changer and some same Na different mag objectives (Finite CFN). 20x/0,75 is effectively replacing 40x/0.75 in my setup (10x/0,45 ; 20x/0,75 ; 40x/1.3 is practically the trio i use).
I think i did posted 40x oil vs 100x oil on this forum once, but cant find it now, and not sure if it had mag changer in, or just crop.

So you are saying amount of CA does not change when magnification gets higher! If this is the case, sure, Lou's answer is better in this case. But this is contradicting what Lou is saying that CA does get blown up as magnification goes up and this invalidates all arguments based on that.

It's not contradicting at all, it's image "equivalency" again. Total amount of CA remains constant, althrough physical size on sensor is enlarged along with whole image.

Bu after taking the photo, you have to make a print. So you WILL enlarge it again. Now you enlarge m4/3 more than you enlarge FF and amount of CA ends up equal anyway.

[mjkzz]

It's not contradicting at all, it's image "equivalency" again. Total amount of CA remains constant, althrough physical size on sensor is enlarged along with whole image.

Bu after taking the photo, you have to make a print. So you WILL enlarge it again. Now you enlarge m4/3 more than you enlarge FF and amount of CA ends up equal anyway.

I think we have passed that equivalency part and agreed upon that. It is about the absolute CA with respect of magnification on same camera (which is irrelevant). Or put it this way, it is about absolute CA with same objective on 200mm vs on 400mm tube lens.

Anyways, great learning experience.

[Pau]

I think i did posted 40x oil vs 100x oil on this forum once, but cant find it now, and not sure if it had mag changer in, or just crop

Likely you're referring to this post:
http://www.photomacrography.net/forum/v ... 519#220519