02-24-2023 01:46 PM
Hi all,
I recently acquired this EF lens, the II version secondhand and have noticed that unlike the RF 15-35 I tried, no focus scale is indicated in the EV or LCD and that with manual focus the ring does not stop at either end (zero or infinity). Are these issues to be expected? Thanks
Solved! Go to Solution.
02-25-2023 12:33 AM
I tried my EF 16-35 II on my R5 and verified that it does not show the focus scale. My 2 other RF lenses do show the scale.
02-25-2023 12:01 PM
What your seeing is normal for a USM lens with mechanical AF override. The focus ring will continue turning 360 degrees. Have you ever used an EF Mount USM lens. Almost all of them work this way. Micro Motor USM lenses DO NOT support MF override. Except the EF 50mm F/1.4 USM lens. It has an additional clutch system to allow MF override just like ring type USM lenses have. Some USM lenses use an electronic focus ring like STM lenses. All RF lenses whether STM or USM use an electronic focus ring.
-Demetrius
Current Gear: EOS 5D Mark IV, EF 16-35mm F/2.8L III USM, EF 24-70mm F/2.8L II USM, EF 50 F/1.8 STM, EF 85mm F/1.8 USM, EF 70-200mm F/2.8L IS III USM, 470EX-AI & 600EX II-RT
Retired Gear: EOS 40D & Sigma 17-50mm F/2.8 EX DC OS HSM
02-25-2023 12:05 PM
I don't have this particular lens, but I think that's normal. The ring isn't mechanically linked to the focus mechanism. Rotating the ring triggers sensors which pass the instruction to the focus motors to move the lens elements. So there's no end stop to the ring's travel. I think it's known as focus-by-wire.
02-25-2023 12:12 PM
Actually this is NOT true for Canon's EF 16-35mm lenses. They have focus rings mechanically connected to the focus elements. Almost ALL Ring Type USM lenses provide mechanical AF override. Some of Canon's early Ring Type USM lenses are focus by wire like STM lenses. The Canon EF 85mm F/1.2L II USM was Canon's last focus by wire Ring Type USM lens. ALL RF Mount lenses use electronic focus rings whether STM or USM.
-Demetrius
Current Gear: EOS 5D Mark IV, EF 16-35mm F/2.8L III USM, EF 24-70mm F/2.8L II USM, EF 50 F/1.8 STM, EF 85mm F/1.8 USM, EF 70-200mm F/2.8L IS III USM, 470EX-AI & 600EX II-RT
Retired Gear: EOS 40D & Sigma 17-50mm F/2.8 EX DC OS HSM
02-25-2023 12:25 PM
Glad to get authoritative information, thanks Demetrius for putting me right.
Can I ask some clarification information, then? I think I did know that EF USM lenses had a mechanical focus linkage, I'd just forgotten. Am I right that you can check this by rotating the focus ring when the lens is not powered up - if the focus mechanism moves there's a mechanical linkage, if not then it's focus by wire?
Secondly, if there's a mechanical linkage between the focus ring and the internal focusing mechanism, why doesn't the ring stop at the infinity and closest focus positions? Is there a clutch that disengages at these points, as you describe for the EF 50mm?
Thirdly, when you state that all RF lenses use electronic focus rings, is that the same as focus by wire? All my lenses are now RF (except I still have an EF 40mm pancake lens, which is STM and I know that's focus by wire).
Forgive me for hijacking this thread, I'm just always hungry for more knowledge about this sort of stuff.
02-25-2023 12:53 PM - edited 02-25-2023 01:03 PM
-Demetrius
Current Gear: EOS 5D Mark IV, EF 16-35mm F/2.8L III USM, EF 24-70mm F/2.8L II USM, EF 50 F/1.8 STM, EF 85mm F/1.8 USM, EF 70-200mm F/2.8L IS III USM, 470EX-AI & 600EX II-RT
Retired Gear: EOS 40D & Sigma 17-50mm F/2.8 EX DC OS HSM
02-25-2023 12:09 PM
Thanks to everyone answering here. This is the first time I have used an EF USM lens, so now I know 🙂
02-25-2023 12:21 PM
Note some EF USM lenses use an electronic focus ring. In order to manually focus you must half press the shutter button and turn the focus ring. Manual focus will NOT work if the shutter button isn't pressed half way regardless if the AF/MF switch is set to MF. This also applies to EF STM lenses too. This doesn't apply for the 16-35mm because the focus ring is mechanically connected to the focus elements.
-Demetrius
Current Gear: EOS 5D Mark IV, EF 16-35mm F/2.8L III USM, EF 24-70mm F/2.8L II USM, EF 50 F/1.8 STM, EF 85mm F/1.8 USM, EF 70-200mm F/2.8L IS III USM, 470EX-AI & 600EX II-RT
Retired Gear: EOS 40D & Sigma 17-50mm F/2.8 EX DC OS HSM
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