What's with electronic focus rings?

Started by ItsMeLenny, May 27, 2018, 12:47:54 PM

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ItsMeLenny

I was super keen to get the 10 to 18mm EF-s lens until I just found out that the focus ring on it isn't mechanical.
It's one of those ones that spin forever which I assume has to communicate with the camera to communicate back to the lens.
Are they doing this with kit lenses for ef-s cameras as well nowadays?

Erik Krause

Yes, AFAIK all STM lenses use focus-by-wire: https://photo.stackexchange.com/questions/24109/what-does-stm-mean-on-a-canon-lens

STM (stepper motor) allows for (almost) silent autofocus, contrary to USM and classical DC motor, which are pretty loud.

allemyr

Hmm ok, USM motors pretty loud?  :D

Some STM lenses sound more that several USM lenses.

I think you have to specify which lenses you meen, aswell as I should do it maybe.

I think in noise from AF Canon DC motors is in its own league!

ArcziPL

Primes with STM are audible, zoom lenses with STM are absolutely silent.

USM is quiet for photography but loud enough to be catched by a microphone located near camera while recording a video with AF.

All in all USM is my favorite for photos -- quick, quiet but I still hear if it works a provides a great manual focus capability. STM's focus by wire is for me a no-go for manual operation. I find it, at least in Canon's implementation, unusable. However for videos with AF or with lenses, which I never use in manual focus (tele), STM is great.
M50.110 [main cam] | G7X III [pocket cam] | 70D.112 [gathers dust] | M.202 [gathers dust] | waiting for M5II

ItsMeLenny

Yeah I think I'm going to have to buy the next 10mm up in price to get a USM instead of an STM.
I think my kit lenses are USM and my 50mm is canons noisey motor, but I don't have autofocus in video on the 550d anyway.

Erik Krause

My USM lenses make a frictional noise, even when focused manually (and no, I didn't spend any time in the desert ;)  they did so since they where new). This is audible in a recording with my hot shoe Rode Mic (not to speak of internal mic). The EF 24-105 is loudest, followed by the EF 100-400, the EF 100mm Macro is best, but still worse than the broken down EF 18-55 STM of my son.