FE lenses on APS-C cameras.

[thebeardedgroundsman]

I saw an interesting comment in an article on the differences between FE lenses and E lenses.

It made the point that the best part of the glass is usually towards the centre (I guess this is especially true on cheaper lenses) so using FE lenses on APSC cameras, or cropping down on a Full Frame camera can give better results than the equivalent E lens. - obviously you lose the benefit of a smaller, lighter unit. Still, worth thinking about, particularly if you have both types of body.

Edited August 30, 2021 by thebeardedgroundsman

[Pieter]

You have a point to some degree. It's not neccesarily worse glass towards the edges but the effects of mechanical vignetting and refraction are more significant there, causing more optical defects toward the edge of the frame.

What you should understand is that the pixel density of a crop sensor camera is often much higher than a fullframe camera. The lenses designed for crop sensors must therefore be able to resolve this higher pixel density and are molded/ground to a higher precision than regular fullframe glass. Only fullframe lenses that perform well on an A7RIV-camera are capable of resolving well on APS-C sensors, but these are often very big and expensive.

So generally speaking, it's not good practice to buy FF glass to use on your APS-C camera, thinking you get the best results.

Though sometimes his assessments are questionable, Tony has some good points on this matter:

https://youtu.be/S8-vfiq33R4

Edited August 30, 2021 by Pieter

[XKAES]

There's some general truth to this, but requires some consideration.

On most lenses, when used at wide apertures, the resolution is better in the center than at the edges.  So using only the center portion of the image would yield better resolution than the same lens with a larger film/sensor.  That, of course, assumes that the two cameras have the same Mega Pixels

But, if you look at the resolution charts/tables for many lenses, as the lens is stopped down, the resolution in the edges increases and can be equivalent to that of the center.  Here's just one example:

http://www.subclub.org/fujinon/e-lenses3.pdf

It also depends on the design of the lens.  Lenses with wider image circles (for larger film/sensors) typically have more elements/groups (reducing resolution), and smaller apertures to reduce costs -- they are also typically larger and heavier, as mentioned.

So it's easy to end up comparing apples and oranges.  It's easy to armchair philosophize about what a lens might or should or probably will do.  The best thing is to run some simple tests.

[michelb]

FF lenses will have larger glass elements that can cause additional flare

[thebeardedgroundsman]

It just goes to show how even experts have differing views.

But what I am hearing is that the lenses designed specifically for one type of camera or another are probably the best for that job - makes sense.

At the end of the day, if the image produced pleases the photographer (or client , if professional) then it's doing it's job.