EF lens design shrunk to EF-M specs

[jefflinde]

would it be possible to take an EF lens formula and shrink it to make it work on the shorter flange distance for the EOS M? I know they make an adapter but if you could shrink the lenses formula that would allow you to build EF-M native lenses with out having to redesign from the ground up.

Just curious.

 

[Mika]

Generally speaking, optics tend to work fine with downscaling. In the case of EF-M, yes that would indeed be possible. But the question is, does it make sense to do that? Occasionally, downscaling from full-frame's 43.2 mm image diagonal to 21.6 mm diagonal makes aberration correction (astigmatism and coma) easier by roughly a factor of four.

This tends to allow a reduction in the number of components in the objective, thus reduction in the price. So a designer might find himself in a situation that he can take away one lens from the formula without affecting anything much, or with only small performance degradations. Without a very good reason, this is often the case that happens.

For example, take a look at Sigma's 30/1.4 Art (DC=APS-C) and at Sigma's 35 50/1.4 Art (DG=FF) where the number of lenses is noticeably less in the 30 mm version. This did come with a slight compromise on the lens performance, though.

Does this answer your question?

EDIT: Oh, forgot to mention that upscaling an optical design doesn't work as nicely as typically the optical aberrations increase at least quadratically, so the general rule is down-scaling is OK, up-scaling isn't.

EDIT^2: Mika isn't paying attention today. Of course it should say 30/1.4 Art and 50/1.4 Art as we are talking about comparable FOV with scaling...

 

[ajfotofilmagem]

You mean to ignore the adapter and use EF-S lenses directly into a body EOS-M?

In this case the inverse would use a macro extension tube. That is, would be impossible to focus on close objects, and may be able to focus only at infinity.

Also, you would be losing the benefit of using native EF-M lenses small and light, as the camera is small and lightweight.

 

[ChristopherMarkPerez]

The current EF lenses are designed around the requirements of the mirrorbox. To make a lens smaller would likely require a re-design. BUT... that's pretty easy to do with the current design methodologies. What'd be the tough part is stuffing yet more lenses down the production line, with all the start-up costs that this implies.

would it be possible to take an EF lens formula and shrink it to make it work on the shorter flange distance for the EOS M? I know they make an adapter but if you could shrink the lenses formula that would allow you to build EF-M native lenses with out having to redesign from the ground up.

Just curious.

 

[jefflinde]

Generally speaking, optics tend to work fine with downscaling. In the case of EF-M, yes that would indeed be possible. But the question is, does it make sense to do that? Occasionally, downscaling from full-frame's 43.2 mm image diagonal to 21.6 mm diagonal makes aberration correction (astigmatism and coma) easier by roughly a factor of four.

This tends to allow a reduction in the number of components in the objective, thus reduction in the price. So a designer might find himself in a situation that he can take away one lens from the formula without affecting anything much, or with only small performance degradations. Without a very good reason, this is often the case that happens.

For example, take a look at Sigma's 30/1.4 Art (DC=APS-C) and at Sigma's 35 50/1.4 Art (DG=FF) where the number of lenses is noticeably less in the 30 mm version. This did come with a slight compromise on the lens performance, though.

Does this answer your question?

EDIT: Oh, forgot to mention that upscaling an optical design doesn't work as nicely as typically the optical aberrations increase at least quadratically, so the general rule is down-scaling is OK, up-scaling isn't.

EDIT^2: Mika isn't paying attention today. Of course it should say 30/1.4 Art and 50/1.4 Art as we are talking about comparable FOV with scaling...

this does answer my question. thank you.