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Can damage be done to a lens if you Manual Focus when Auto Focus is on?
I let my dad play around with my 450D. And he kept manually focusing when Auto Focus was selected on the lens (Tamron 17-50 2.8). He told me focusing was quite hard, then I realised it was probably set to Auto! He only played around with it for about 30 seconds..

But my question is, is there a chance it could have damaged my camera or lens?.

I'm a bit anxious to be honest....

Brand new lens and all! .

Still seems to be focusing fine now, but because it's new, I can't be sure if it's focusing as well as it should be...

Comments (11)

Until someone more knowledgeable than myself answers, I will take a guess..

First, I would be as frightened as you are that someone forced the focusing ring against pressure. You would think it might strip the gears..

On the other hand, take your camera, put it on continuous focus,and move around pointing the camera at near and far objects. If you hear the sporadic whine of the focusing motor everytime you point at a new object, the lens is probably OK...

Comment #1

Kd6vm wrote:.

Until someone more knowledgeable than myself answers, I will take aguess..

First, I would be as frightened as you are that someone forced thefocusing ring against pressure. You would think it might strip thegears..

On the other hand, take your camera, put it on continuous focus,andmove around pointing the camera at near and far objects. If you hearthe sporadic whine of the focusing motor everytime you point at a newobject, the lens is probably OK..

I do indeed hear the motor. Working as normal by the "sounds" of things. Not sure if it's working perfectly in practise though..

I did just do a manual test, AF vs 10x magnified personal manual focus, and both were about as sharp as each other (dependant only on how steady I was). So I'll take that as an example the AF (lens motor) is still fine...

Comment #2

NaimC wrote:.

I let my dad play around with my 450D. And he kept manually focusingwhen Auto Focus was selected on the lens (Tamron 17-50 2.8). He toldme focusing was quite hard, then I realised it was probably set toAuto! He only played around with it for about 30 seconds..

But my question is, is there a chance it could have damaged my cameraor lens?.

Well, you did not damage the camera. As far as the lens, it depends on the lens AF motor whether there is any damage. On Canon ring USM lenses, it does not damage the lens, since those lenses have full-time manual focus (even with AF selected). On most other lenses, you can strip the gears for the AF motor..

Since the focus was hard on your lens when set to AF, chances are that it was not meant to be manual focused in AF mode. You may have worn down the gears in the AF motor a little, but if you can still AF, I wouldn't worry too much (just don't do it again)...

Comment #3

Yes, he might! As pointed out, the camera is OK, the problem is possibly with the lenses..

Only those lenses with built in motor maybe adjusted manually at all times. Some others, like some of the Pentax limited or FA* lenses, the user can push or pull on the focusing ring to disengage the focus gear and make focusing by hand..

When you find it hard to adjust on something, you better stop and find out why. For a short while, maybe it is alright. BUt do check it out...

Comment #4

If AF is switched on you should not manually focus whilst depressing the shutter button half way. But mauall focussing whilst not depressing the button with AF on is fine, I do it a lot to help the AF make it's mind up in difficult focussing shots.Jules.

Why can't you blow bubbles with chewing gum?..

Comment #5

JulesJ wrote:.

If AF is switched on you should not manually focus whilst depressingthe shutter button half way. But mauall focussing whilst notdepressing the button with AF on is fine, I do it a lot to help theAF make it's mind up in difficult focussing shots.Jules.

This only applies to ring USM lenses. It does not apply to micro-motor, AFD, or micro-USM lenses, which all use gears to move to AF motor - so you should NOT try to MF when in AF mode with these lenses. It does not appear that the lens the OP had was a ring USM lens..

For information on the different types of Canon lenses, see the following link:.

Http://photo.net/photo/canon/lens-motors.

Hope this helps...

Comment #6

Should there not be mention of this in the lens instructions, it's easy enough to contact Tamron and ask them..

Best regards,Doughttp://pbase.com/dougj.

Http://thescambaiter.comFighting scammers WW for fun & justice..

Comment #7

I have the Tamron 17-50, it is not designed, as Canon USM lenses are, to be manually focused in AF mode. Certainly the motor/gears can be damaged this way..

Mark..

Comment #8

Ha, whoever read lens intructions? I take them out the box when the camera is new, put them on the camera and chuck the paperwork away. A lens that needs explaining is a lens I don't need.jules.

Doug J wrote:.

Should there not be mention of this in the lens instructions, it'seasy enough to contact Tamron and ask them..

Best regards,Doughttp://pbase.com/dougj.

Http://thescambaiter.comFighting scammers WW for fun & justice.

Why can't you blow bubbles with chewing gum?..

Comment #9

JulesJ wrote:.

If AF is switched on you should not manually focus whilst depressingthe shutter button half way. But mauall focussing whilst notdepressing the button with AF on is fine, I do it a lot to help theAF make it's mind up in difficult focussing shots..

On ring USM lenses (or the 50mm f/1.4 micro-USM) it's perfectly fine to play with the focus ring any time..

On Canon AFD lenses (not many still made... 15mm fish, 24/2.8, 28/2.8, 35/2, 50/2.5 macro, 135/2.8 SF, did I miss any?) you can also do it any time. The focus ring is physically disconnected from the motor gears when the lens is switched to AF, so it spins freely and does nothing..

On all other Canon lenses, micro-motor or micro-USM, don't touch the focus ring in AF!.

I don't know about Tamron, but assume it is similar to micro-motor..

Seen in a fortune cookie:Fear is the darkroom where negatives are developed..

Comment #10

Dave_s93 wrote:.

This only applies to ring USM lenses. It does not apply tomicro-motor, AFD, or micro-USM lenses, which all use gears to move toAF motor - so you should NOT try to MF when in AF mode with theselenses..

On AFD lenses the focus ring is physically disconnected from the gears. Spin at will, it does nothing..

Seen in a fortune cookie:Fear is the darkroom where negatives are developed..

Comment #11

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This question was taken from a support group/message board and re-posted here so others can learn from it.

 

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