Focusing to Infinity

[pborgbarthet]

I have read a lot of posts on these forums and the term 'focusing on infinity' is mentioned many times. Can someone explain this to me...possibly with reference to the Canon EOS 350D. I have the 18-55 kit lens.

Thanks

 

[darich]

It means exactly what it says - focussing on the furthest away point in the viewfinder. Alternatively simply set the focus to the furthest away point without looking through the viewfinder.

I believe that doing this means that most of the image is in focus and useful for astonomy images or probably even landscapes....but i've never tried that - i always put something in the forground and focus on that.

I'm sure someone more knowledgeable wil be along soon to explain it better.

 

[bencze]

I would be curious of how this works as well. There are situations when I try to take a picture of a landscape or some city picture - in any case, objects that are far away. Very often I am not sure what to focus on. And if it is a picture where I have many objects at a distance, I am not even sure if the autofocus works correctly; but at that distance I am not even 100% sure how to focus manually to get a sharp picture as a result.
I would like to know what is the minimum distance where I can safely set focus to infinite to get a sharp overall result (guess it may depend on focal length or aperture size).
Not sure if it relates, but I know sometimes it helps to have something in the foreground even if it is something rather insignificant (not the subject), but there are occasions when I just want to capture the whole thing (even if it may not be a technically correct composition).

 

[EOS_JD]

Depends on the focal length.

If shooting at 17mm and f16 (on a 1.6 crop camera) you can focus on anything from 1m away and everything from 0.49m away to infinity will be in focus. You can also try something at 400m away and everything from 0.95m to infinity will be in focus.

Try some dof calculations using this.

http://www.dofmaster.com/dofjs.html

 

[bencze]

ZOMG dof again. I do need to bookmark that site. Awesome.

 

[gizmo2071]

As EOS_JD described, it's called the hyper focus distance. Everything within a certain distance will be in focus, especially good for landscape shots
Not as easy to setup on newer lenses, but still possible with more calculations.

 

[Mike_E]

Way useful in landscapes and street photography where you don't want to be seen taking a picture. Set the hyper focal, manually set the speed, shoot from the hip and crop later.

mike

 

[DSLR noob]

Oh how I miss the days of distance scales....... I mean, I am a n00b who is only 17 years old and has been into photography for only half a year, but I do have old FD lenses. Those scales are helpful, and personally, the lenses look more advanced with them.

 

[cosmonaut]

As a general rule you can focus a third of the way into a shot and you will be at hyperfocal distance.
Cosmo

 

[EOS_JD]

For wide angl lenses, it should be pretty easy to shoot with manual focus. The depth of field is generally huge (even at larger apertures like f4)

 

[nrdm]

As a general rule you can focus a third of the way into a shot and you will be at hyperfocal distance.
Cosmo

I heard of this "rule" before when taking landscapes to make sure everythings in focus. Is this similar to focusing on infinity?

 

[EOS_JD]

Focusing to infinity is a matter of depth of field.

So that comes down to focal length, distance to subject and aperture.

 

[New Hampshire]

Oh how I miss the days of distance scales....... I mean, I am a n00b who is only 17 years old and has been into photography for only half a year, but I do have old FD lenses. Those scales are helpful, and personally, the lenses look more advanced with them.

DOF Preview button on your camera can be your best friend! :mrgreen:

Brian