Damage to camera motor or lens if we manually turn focus on AF and without pressing shutterbutton?

[egosumcarlo]

Hi. Thanks for all the assistance. I'm still new to DSLRs and please excuse my dumb questions. I'm using the EF-S 18-135 IS USM lens that came with the Canon EOS 80D. I've read that given that it is nano USM, it is alright to manually turn the focus ring even when AF is on. Is this correct? Also, before I was able to read some more, I have been manually turning the focus ring with AF=on and without pressing the shutter button halfway. Can this harm the camera motor and/or the lens? Thank you very much in advance for your inputs.

[lly3988]

Your lens supports full time manual focus. Nothing to worry about rotating manual focus ring in AF mode.

[TCampbell]

USM and STM lenses support full-time manual focus (you wont hurt the camera if you manually focus when auto-focus is enabled).

This is because USM (ultra-sonic motor) lenses have a clutch that allows the focus ring to "slip" -- you'll notice if you rotate the focus ring all the way to either minimum or maximum focus distance... you can still rotate the ring.   You'll feel the drag of the clutch as it lets the ring slip, but it wont hurt anything.

Though you didn't mention having an STM lens... on STM (Stepper Motors) the lens is "focus by wire" meaning there's actually no direct connection to the focusing elements in the lens at all.  The camera controls all movement (even manual focus).  But in manual focus mode is just responds to your input.  The unusual thing about the STM lenses is that since they are "focus by wire" lenses... the camera isn't actually always watching for input.  You have to "wake up" the focus system (typically a half-press of the shutter button or use the AF-On button) and then the focus will respond to manual focus input.

The lenses that have neither the "USM" or "STM" suffix are not focus by wire, do not have a clutch, and do not support "full time" manual focus.  They are more basic entry-level lenses.  

[MikeSowsun]

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@TCampbell wrote:

USM and STM lenses support full-time manual focus (you wont hurt the camera if you manually focus when auto-focus is enabled).

This is because USM (ultra-sonic motor) lenses have a clutch that allows the focus ring to "slip" -- you'll notice if you rotate the focus ring all the way to either minimum or maximum focus distance... you can still rotate the ring.   You'll feel the drag of the clutch as it lets the ring slip, but it wont hurt anything.

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In the past Canon has sold many “USM” lenses that do NOT support full-time Manual focus. The Canon EF 70-300mm f/4-5.6 IS USM is one example still being sold. This lens can be damaged by turning the focus ring while in AF mode. 

Canon made 2 types of USM lenses but neglectted to point out the operational differences between “Ring Type” and “Micro Motor” USM in the general information on each lens. Now Canon has further confused the issue by adding Nano USM lenses. 

You really need to look at the manual to see if you have full- time manual focus. This lens does not.......

[lly3988]

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" I'm using the EF-S 18-135 IS USM lens that came with the Canon EOS 80D. "

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The other replies brought up an interesting point.

Which version is your EF-S 18-135 IS USM lens ?

According to Kenrockwell page, there are three different versions of EF-S18 135mm lenses. The first  version (non USM) lens won't support full time manual focus and one has to switch AF/M to change the focus mode.

http://www.kenrockwell.com/canon/lenses/18-135mm-usm.htm

Check which version is your lens and you can decide whether it supports Full Time Manual focus. If yours come with 80D as a kit lens and is the latest Nano version, it supports FTM focus. So, no need to worry.

[egosumcarlo]

Thank you all for the replies. My lens is Nano USM so basing lly3988's explanation, it has Full Time Manual focus. I noticed (and again only belatedly read) that FTM when AF=On only works when AI=One Shot. . I've learned this only after attempting unsuccessfully to manually adjust focus while AI=AI Servo. Nothing happened while I was manually adjusting FTM when AI=AI Servo. I will remember that next time but does it harm the camera and/or the lens when we try to manually adjust while AF and Servo are on?

I heard that the camera will "fight" attempts to manually focus under these settings so I'm concerned that I might have damaged the camera when I tried to adjust focus manually while AF and AI Servo were on.

[ebiggs1]

"In the past Canon has sold many “USM” lenses that do NOT support full-time Manual focus."

I was going to say this but Mike beat me to it.  Not good the think in generalities.  However, besides that overlooked point, why are you pressing the shutter button and at the same time trying to manual focus the lens?  I sometimes get the lens close to the distance I am shooting with the MF ring but when I press the shutter I let the lens/camera do its thing.  So, why, just curious?

[egosumcarlo]

Hi ebiggs1. Good day. My understanding is that even when AF is on, we can manually adjust the focus ring while the shutterbutton is half-pressed if the lens is USM(ring type) or nano USM and this feature is called FTM (Full Time Focus). My lens in this case is a nano-USM so it has FTM. My mistake was manually turning the focus ring when AF Servo was on instead of One Shot. My concern now is whether I could have damaged the lens and/or the camera because my understanding is that when Servo is on and we manually turn the focus ring, the camera will "fight" the manual adjustments. Does this harm the circuitry or the motor inside the lens?

[ebiggs1]

"... we can manually adjust the focus ring while the shutterbutton is half-pressed ..."

I understand that.  It isn't new.  My question is why do you or anybody want to do it?  The lens is going to fight you if you have the shutter button half pressed.  In other words it will not stay where you manually moved it if the lens thought it was in focus.

It is probably better the do it one way or the other.