# Lens Focusing



## noxious_nasties (Dec 29, 2011)

Hi all,

I've been a long time reader of this site (awaiting the 5diii since the 5dii came out). I don't claim to be a pro, or even a good photographer, but since the 5dii has came out I've been keen on learning about dslr's. I have never officially owned a dslr, but have borrowed a 550d and 600d numerous times. Since the release of the 5dii I've been learning all I could about these fascinating camera's and lenses and in the process, waiting for the 5diii to be released and saving up (being a student). If the 5diii does come out and it's not what I'm after I'll be on the boat for a cheap 5dii. I have used a canon ae1 program and developed b/w film which was great.

Anyway, I recently purchased my first lens due to the canon rebates going on the USA (i'm from aus). It was the 100mm 2.8L macro, which being under 1000 saved me the 10% gst tax. I've always been confused about focusing on either AF or MF modes. I generally presume you shouldn't change the focus if in AF mode, but with the 100mm L it states "The focusing ring always works regardless of the focus mode." Brief research tells me that it's dependant on whether the camera has an USM. Don't know much more. If someone can tell me what damage can occur on certain types of lenses from incorrectly using the focus (if possible) that would be great.

John


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## wickidwombat (Dec 29, 2011)

I think Neuro can probably give you a more detailed answer
but I think you are refering to the Full time manual over-ride focusing I am certain the 100 f2.8L macro has this
Its a nice lens I have one too. basically it means if you use AF then turn the focus ring or even if you are holding the focus ring and use the AF a clutch mechanism will release internally and not cause any damage to the lens. 
One lens i am fairly sure that doesn't have this is the 50mm f1.4 which i think you have to be carefull to not hold the focus ring when using AF

hope that helps


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## nightbreath (Dec 29, 2011)

Hi John,

I believe there's nothing you can do to break the lens or camera body if you treat them carefully. I.e. don't drop or put it into sand / water and everything will be ok


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## Leopard Lupus (Dec 29, 2011)

Neuro has mentioned this in a previous post, I believe ??? 

From what I know, the 100 f/2.8L will not be harmed when your switch is on AF and you manual focus. In the case of the 50mm f/1.4 brought up by Wickidwombat, if the lens is on AF and you manually focus, it will damage the lens. 
Congrats on the new purchase!


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## handsomerob (Dec 29, 2011)

noxious_nasties said:


> Hi all,
> 
> I've been a long time reader of this site (awaiting the 5diii since the 5dii came out). I don't claim to be a pro, or even a good photographer, but since the 5dii has came out I've been keen on learning about dslr's. I have never officially owned a dslr, but have borrowed a 550d and 600d numerous times. Since the release of the 5dii I've been learning all I could about these fascinating camera's and lenses and in the process, waiting for the 5diii to be released and saving up (being a student). If the 5diii does come out and it's not what I'm after I'll be on the boat for a cheap 5dii. I have used a canon ae1 program and developed b/w film which was great.
> 
> ...



It's not the camera that has USM, it's the lens. There are two types of USM : Ring-type USM and micromotor USM. 
Ring-type USM allows full-time manual focus (along with very silent and very fast AF) without switching out of AF mode. Lenses with micromotor USM don't have this feature. I think all L lenses have ring-type USM so they will always allow full-time manual focus.

So, no worries, you can override the focus anytime you like on your 100L macro, even if the AF is switched ON. This won't damage the lens what so ever.

Btw, if I were you, I would get a 5DII *now* (not sure if it will get any cheaper) and start shooting  
5DIII is at least a couple of months away at best and will cost lots more.


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## BumpyMunky (Dec 29, 2011)

wickidwombat said:


> One lens i am fairly sure that doesn't have this is the 50mm f1.4 which i think you have to be carefull to not hold the focus ring when using AF



Not to stray too much, but the 50 1.4 still has full-time manual (FTM) focusing (it may in fact, be the only micro-motor USM that does). It's the 50 1.8 that doesn't have FTM.

See:
http://www.canon.com/camera-museum/camera/lens/ef/data/standard/ef_50_14_usm.html
http://en.wikipedia.org/wiki/Canon_EF_lens_mount#Ultrasonic_Motor_drive

Basically, with FTM, you can manually focus regardless of what position the AF/MF switch is in. 

If the lens doesn't support FTM, moving the focus ring while the lens is in AF mode (or conversely, preventing the ring from rotating when the AF is trying to focus the lens) can damage the focus motors and/or gears. The noise that happens when this is attempted is usually enough to cure one from doing it again.


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## noxious_nasties (Dec 29, 2011)

Thanks All,

So the basic rule of thumb is all L series have FTM capabilities as well as any other canon lens that has a Ring type motor.

Lessen learnt. Apologies if this was brought up earlier.


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## D.Sim (Jan 10, 2012)

Welcome to the world of FTM... Would be a good idea to always check if your lenses have FTM or not - regardless of whether its L... You can never be too sure, something might happen somewhere along the line. 

totally agree with BumpyMunky on the noise you can hear if you focus on a non-FTM lens - or even accidentally stop the focus ring from moving. You learn real quick. You'll probably also learn to store the lens set on MF, to avoid accidents while using it. Oh the other hand, the 100mm L Macro is awesome, you wouldn't have that problem with it... might want to be careful how you store it while waiting for a camera to mount it on though.


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