RF 135 f/1.8

[Joel Eade]

That certainly is impressive!

[Sinh Nhut Nguyen]

I wish Canon would make an adapter for RF lenses to use on Canon DSLR. I recently added the EF 70-200 f2/.8L IS III to my kit if there is such adapter I would totally go with the RF 70-200 f/2.8L IS.

[Kayaker72]

I wish Canon would make an adapter for RF lenses to use on Canon DSLR. I recently added the EF 70-200 f2/.8L IS III to my kit if there is such adapter I would totally go with the RF 70-200 f/2.8L IS.

Unfortunately, this is impossible. The Flange Back distance on the RF lenses is 20 mm while that distance on EF lenses is 44 mm. This is the physical distance from the back of lens (usually a metal ring on L glass) to the sensor. With the RF being 24 mm closer than EF, you can use a 24 mm adaptor to adapt EF to RF mount. But, unfortunately, it cannot work the other way around because the RF lens would be moved 24 mm further away from the sensor, thus, a 50 mm RF lens would be 74 mms away from the sensor and the lens elements would not be properly focusing the image on the sensor.

Here is an article talking about this and other aspects of RF vs EF, Flange Back differences is illustrated about 3/4 of a page down.

Enjoy your "new" EF 70-200 III.

For what it is worth, I have yet to purchase a single RF lens. Still using the EF glass. Not surprisingly, it works extremely well on the R5. About the only flaw with this that I have found so far is that with video you can hear the USM motors while focusing the EF lenses. The motors on RF lenses are supposed to be much quieter.

[Sinh Nhut Nguyen]

Unfortunately, this is impossible. The Flange Back distance on the RF lenses is 20 mm while that distance on EF lenses is 44 mm. This is the physical distance from the back of lens (usually a metal ring on L glass) to the sensor. With the RF being 24 mm closer than EF, you can use a 24 mm adaptor to adapt EF to RF mount. But, unfortunately, it cannot work the other way around because the RF lens would be moved 24 mm further away from the sensor, thus, a 50 mm RF lens would be 74 mms away from the sensor and the lens elements would not be properly focusing the image on the sensor.

Here is an article talking about this and other aspects of RF vs EF, Flange Back differences is illustrated about 3/4 of a page down.

Enjoy your "new" EF 70-200 III.

For what it is worth, I have yet to purchase a single RF lens. Still using the EF glass. Not surprisingly, it works extremely well on the R5. About the only flaw with this that I have found so far is that with video you can hear the USM motors while focusing the EF lenses. The motors on RF lenses are supposed to be much quieter.

Thank you for the explanation, I had no knowledge of the physical limitation. I was out of the game for over 5 years. I heard EF lenses work better on mirrorless than they would on DSLR, is this true?

[Jonathan Huyer]

I heard EF lenses work better on mirrorless than they would on DSLR, is this true?

Well you don't have to do any AF microadjustment with lenses on mirrorless cameras, and there is some improvement in stabilization due to the IBIS working with the lens IS. Otherwise I'm not sure what the differences might be. Maybe the focusing is faster? I would be surprised if that were true.

[Kayaker72]

Thank you for the explanation, I had no knowledge of the physical limitation. I was out of the game for over 5 years. I heard EF lenses work better on mirrorless than they would on DSLR, is this true?

Well you don't have to do any AF microadjustment with lenses on mirrorless cameras, and there is some improvement in stabilization due to the IBIS working with the lens IS. Otherwise I'm not sure what the differences might be. Maybe the focusing is faster? I would be surprised if that were true.

I would say that EF lenses work remarkably well on my R5.

Better? No, I wouldn't say the lenses are better on RF mounts.

I think there are advances to recent bodies and that those bodies happen to be mirrorless. But, then you are really getting into a discussion about 2020 or more recent technology that received a lot of investment vs 2016 (going with 5DIV for a date) technology that Canon wasn't necessarily investing in as much (my speculation).

The cameras can do more. Just to add to Jonathan's list: AF spread, AF-eye detect, level/histogram in EVF, more fps, less interference with AF due to mirror movement, ability to shoot 1.6 crop, customization of buttons, etc.

But I never want it to get lost, the image quality is primarily a function of the lens was great on DSLRs. If a mirrorless body improves that, I think it is mostly due to generational improvements to filters/sensors/processors and not the lens itself.

[Fast Glass]

The cameras can do more. Just to add to Jonathan's list: AF spread, AF-eye detect, level/histogram in EVF, more fps, less interference with AF due to mirror movement, ability to shoot 1.6 crop, customization of buttons, etc.

Not to take away from what you said, but the 5Ds could also do 1.6 crop modes. Which is a bit of a misnomer because it doesn't really crop anything and just basically a guide for you to crop in post, if shooting RAW. Which I don't really find super helpful, unless you want to shoot 1.6 crop lenses. But would anyone really do it? Probably not many.

If it gained me a smaller file size for more buffer, faster FPS, 14 bit instead of 12 (A caveat with shooting 20fps on the R5 or R6) then yeah. I could see myself using it, but if I'm still managing full rez images regardless. Not super useful to me.