Focussing to infinity??

[Nathaxthelarge]

Also, what does it mean focus to infinity? I dont understand how to do this...

 

[John Mc]

Its used mostly in landscape and wide angle shot's. but i could be wrong,if someone could correct me if i am.

 

[MichiganFarts]

Something like, at a certain distance from the lens, everything is considered in focus...I'm not sure the technical explanation.

 

[Nathaxthelarge]

I see what you mean. How do you do it?

 

[MichiganFarts]

I believe there's an infinity mark on you lens that shows you where infinity is.

Looks like an 8 resting on its side..

 

[John Mc]

Theres not one on a Kit lens. Well a Canon Kit lens atleast.

 

[Nathaxthelarge]

I know what infinity looks like.. Ill never forget it after uni maths.. haha. I believe i havent experienced it yet because my lenses cannot focus to infinity, ive only got the lens kit. At least i know for the future!!

 

[pgriz]

There are two separate ideas. "Focusing at infinity" can either mean that literally you align the lens focus mark on the infinity symbol (which would be a waste of lots of depth-of-field), or it can be referring to focusing to the hyperfocal distance, which allows you a maximum depth-of-field, with the far side of the depth-of-field range to extend to infinity.

Prime lenses usually have the f/stops engraved on the barrel of the lens on either side of the lens focus point. To achieve a desired depth of field, one chooses a focus distance so that the chosen f/stop covers the desired range. To focus on the hyperfocal distance, one chooses the f/stop (say f/22) and align the 22 engraved on the lens barrel with the infinity mark on the lens distance scale. The lens focus mark will be aligned with the "target" distance, and the other 22 on the barrel will be aligned with the closest focusing distance.

Since the depth of field also varies according to focal length, Zoom lenses do not have these convenient DOF markers on the barrels. So you have to use tables (such as at www.dofmaster.com) to calculate the desired depth of field for your specific local lenght, aperture, and sensor size.

 

[Robin Usagani]

At some distance from your lens if you focus to that disance, everything on that range and farther will be in focus. Lets say you see a mountain. There is a cabin far away. You cant make the cabin in focus and the mountain blurred once you reach this infinity distance. If you go closer or zoom closer until you are closer than the infinity distance, then the mountain starting to blur. This infinity distance varies between focal length.

P.S. That is just my understanding. I never read it from anywhere. So correct me if im wrong.

 

[MichiganFarts]

At some distance from your lens if you focus to that disance, everything on that range and farther will be in focus. Lets say you see a mountain. There is a cabin far away. You cant make the cabin in focus and the mountain blurred once you reach this infinity distance. If you go closer or zoom closer until you are closer than the infinity distance, then the mountain starting to blur. This infinity distance varies between focal length.

P.S. That is just my understanding. I never read it from anywhere. So correct me if im wrong.

Yeah, this is more or less the way I had understood it. I can't be sure if my memory from 10 years ago is all that great though lol.

 

[erkh]

you should read about hyperfocal

 

[enzodm]

I believe i havent experienced it yet because my lenses cannot focus to infinity, ive only got the lens kit.

Your lens of course can, every time you take a picture of something very far.
Or: switch off autofocus, and manually focus to something very close (0.25m if you have 18-55IS). Then rotate the focus ring fully on the other side: there you will find the infinity (in optical sense) (and first meaning according to Pgriz explanation).