Canon EF lens question

How can I tell the difference between the EF lenses for film SLRs and mirror-less DSLRs? I apparently have a mirror-less one on my EOS 10S because the 80 mm zoom looks like it's 50mm and I'm not sure it's focusing on infinity.

Any help is appreciated.

There are EF lenses, these work on film, digital and crop(APS-C) digital canon cameras. The canon EF-S lenses only work on the canon crop digital cameras. The mirrorless canon's (EOS-M series) use the EF-M mount. The EF lenses will work on all of these (with an adapter for the eos-m cams). The EF-s and EF-M will not work on the canon eos film or digital full frame cams.

Edited to add: Google is your friend First search that popped up, canon lens mounts. http://en.wikipedia.org/wiki/Canon_EF_lens_mount

I was pretty confused after reading that article, that's why I asked here. So I'm good then if I'm understanding everything. Must be my eyes....

As far as I know, Canon-made EF lenses (for film SLRs and full-frame DSLRs) have a round, red index mark for mounting the lens. Canon's EF-S lenses (for the crop-sensor DSLR bodies) have a square, white index mark. I don't believe it's physically possible to mount an EF-S lens to a full-frame body without modification of the lens, but EF lenses will mount to the crop-sensor DSLRs.

See this picture [wikipedia].

Third-party lenses in these mounts may, or may not, obey this general rule; I just don't know. I've never owned or used any EF-M lenses or cameras, and can't comment on them at all. Hope this helps!

• Don't think 'for film' vs. 'for digital'
• Think 'for FF/135 size sensor/film (24x36mm)' vs. 'for smaller, APS-C format size (15x22mm)

Canon designation are 'EF' for #1, 'EF-S' for#2; you cannot physically mount an EF-S lens on a EF body because the lens mount is different.

Other manufacturers are different, they use the EF lens mounts for all their lenses, but they DO distinguish format size which can be covered by a lens

• Tamron calls #1 lenses 'Di', they call #2 lenses 'Di-II'
• Sigma calls #1 lenses 'DG', they call #2 lenses 'DC'
• Sigma calls #1 lenses 'FX', they call #2 lenses 'DX'

In the early days because lens manufacturers said that WA lenses for digital cameras (with APS-C format) had different optical considerations for very short FL, to improve upon lens sharpness due to the fact that different pixels were sensitive to a single color of light. So 'for digital' had different design criteria than 'for film'. Generally that tends to be secondary consideration of the amateur photography, secondary to the issue of 'will it fill my frame?'

There is at least one Canon digital SLR that pre-dated the EFS mount - the 10D. So even though if has its own cropped sensor, you cannot use EFS lenses on it.

The same goes for the APS film bodies - they take EF mount lenses. The lenses that were introduced with the APS cameras will fit on full frame digital and film bodies, but their corner performance may not satisfy you. That being said, I like my 22mm - 55mm EF zoom on my film bodies, because the range of focal lengths appeals to me, and the lens itself is very compact.