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Author Topic: What's with electronic focus rings?  (Read 2356 times)

ItsMeLenny

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What's with electronic focus rings?
« on: May 27, 2018, 12:47:54 PM »
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?
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Erik Krause

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Re: What's with electronic focus rings?
« Reply #1 on: May 27, 2018, 02:36:27 PM »
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.
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allemyr

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Re: What's with electronic focus rings?
« Reply #2 on: May 27, 2018, 07:45:30 PM »
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!
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ArcziPL

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Re: What's with electronic focus rings?
« Reply #3 on: May 27, 2018, 09:13:53 PM »
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.
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ItsMeLenny

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Re: What's with electronic focus rings?
« Reply #4 on: May 28, 2018, 12:13:03 PM »
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.
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Erik Krause

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Re: What's with electronic focus rings?
« Reply #5 on: May 28, 2018, 04:45:03 PM »
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.
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