Focusing on Infinity - A Dumb Question

[susanjm]

Hi everyone,

I was an SLR user many years ago but haven't really been into photography for a while. After a few years of reasonably good quality digital point and shoots, I'm moving into the world of dSLRs with the purchase of a Nikon D40.

My dumb question is this: the kit lens (AF-S DX Nikkor ED 18-55mm 3.5/5.6 G II) doesn't have a distance ring on it and I can't figure out how to tell if I'm focussed on infinity or not!

Thanks in advance for any answer.

susanjm

[gmtech79]

One way of doing it would be manually focus on your hand extended in front of the lens (the focus ring should now be all the way turned in one direction). Then simply manually move the focus ring all of the way to the opposite direction and it will be focused to infinity, thus your hand will be out of focus and everything far away will be sharper. Hope this helps.

[Vich]

One way of doing it would be manually focus on your hand extended in front of the lens (the focus ring should now be all the way turned in one direction). Then simply manually move the focus ring all of the way to the opposite direction and it will be focused to infinity, thus your hand will be out of focus and everything far away will be sharper. Hope this helps.

Somehow, there's always a "beyond infinity" stop on most lenses.

I know I know, you'll say I'm a Canonite and therein lies my problem, but seriously, I've owned 3 Nikon SLRs over the years and this always seems to hold true.

[gmtech79]

Are you talking about lenses with distance scales that will actually move past the infinity mark?

[Vich]

Are you talking about lenses with distance scales that will actually move past the infinity mark?
It's not marked, just that if you look through the viewfinder (far easier on a film camera due to bigger viewfinder), and you manually focus it to infinity (ie: far distance is in focus), the lens lets you go a little beyond that point and things look slightly OOF.

[the Chris]

If I have read correctly, the solution of setting the D40 with the Kit Lens 18-55mm on infinite focus hasn't been found yet as this point of focus lies not at the end of the focus adjustment range. So, is there a solution?

Yesterday I visited a friend in "Leverkusen", big town next to Cologne. Out of his flat, he has a great view on the skyline of Cologne. Having had a quite clear weather I took some shots (and found out, that I need something beyond 55mm btw.). When darkness came over light, I had trouble to focus on the tiny lights of the skyline as the lightend buildings in the foregound were very dominant (I couldn't get past them because of limited zoom power of the kit lens). I tried to focus manually, but as the lights were tiny I couldn't figure out what setting was the correct "infinite focus".

Any new ideas on infinite focus?

Greetz
Chris

[Prospero]

Vich is right, on many lenses you can focus beyond infinity. I don't have a clue why that can be done, it might enable lenses to be used on different bodies with an adapter (as adapters often stop a lens from being capable to focus on infinity). Anyway, all the three lenses I am using now can focus beyond infinity but I'm not sure if the 18-55 does as well. If it does not gmtech answered your question. If it does, you can do the following.

During daytime auto-focus on something that is 'infinitly' far away. Then mark the top of front element (the ring) in some way, for instance with a white marker. Now, you will always no at which point the lens is focussed on infinity (namely when the white part is in top).

That said, it is not all that important to nail the focus when focussing on something that far away. At focussing distance around infinity, the depth of field is huge (even at large appertures and long focal lengths). Therefore, the lens does not need to be precisely at infinity to have your subject in focus.