can focus past infinity on Canon 70-200

[Jayme Cowley]

Hi, I just picked up the Canon FD 70-200 f2.8 L USM lens.
I've noticed that in manual focus mode, the focus doesn't lock at infinity, or even get any harder to turn. I can fit something tighten a little past infinity (the image is now OOF) but even then I can continue to turn the focus ring.

Is this normal on these lenses, and if not, is it expensive to get fixed at a camera repair shop?

 

[aadhils]

Yea it's normal. I think all lenses can focus past infinity. You just need to figure out out to stop at the right point. Congrats on the new lens! You'll get better as you learn more.

 

[Jayme Cowley]

Great, thank you for your reply. i guess i'm just used to the old FD lenses, i had a 70-210 zoom and the focus ring would never go any further than infinity, but i sounds like the new ef lenses are different.

 

[den9]

it stops at infinite, but you can continue spinning the ring, just like a the volume button in your car. if i understand correctly.

 

[Jayme Cowley]

no, it will focus past infinity, and the image goes out of focus again, there is a sweet spot where inifinity is in focus, but the focus ring will blur the image both before and after that point.

 

[Overread]

Most lenses have a little play at the infinity end of the focus scale - this is to take account of material adjustments with regard to temperature as well as other factors - expansion or contraction of the elements within could cause a fine set infinty point to shift a little - thus the need to have this play at the end of the scale.

Also the USM (ultra sonic motor) focusing works just as you say, you can turn the focus wheel constantly around even though the focus itself has stopped moving. It is part of how these lenses focus manualy and electronically. Also even when the lens is in auto focus mode you can easily turn the focus and adjust it (of course this only works in one shot AF since the AF will turn off after thecamera finds focus - if you are in constant AF mode like AI servo you should never attempt to change the focus manually because you will just get into a fight with the AF motors and end up wearing them down)

 

[D-B-J]

my nikkor 105mm 2.8D micro sticks at infinity. is this a canon-only thing?

 

[Overread]

Any canon lens without USM or any Sigma lens without HSM will "stick" at the end of the infinity scale with it comes to manually focusing (there will of course be the small amount of play at the infinity end for all lenses). I am sure that Nikon has its own named focusing mode similar to Ultrasonic/Hypersonic that canon and sigma use, but I don't know its name or abbreviation.

 

[D-B-J]

Oh, so its the hsm or usm that makes that possible?

 

[Overread]

Yes it also makes it possible to use manual focus whilst the AF switch is set to on (sometimes called "all the time manual focus"). Of course as said there are limits to using that mode, but it can be invaluble for tricks like focus and recompose - where you focus with AF onto the subject, then whilst still holding the shutter button down shift the frame so that a new composition is created - then you can adjust the focus manually a little to correct any change in the plane of focus as a result of recomposing and take the shot.