Paris

by Jon

submit your photo


Hall of Fame
View past winners from this year

Please participate in Meta
and help us grow.

Autofocus is the ability of a camera/lens system to automatically adjust the focus of the lens via a motor attached to the focus group of the lens. Contrast with manual focus.

learn more… | top users | synonyms

19
votes
2answers
1k views

Why am I allowed to turn my focusing ring beyond infinity?

Is there a good reason why I can turn the focusing ring on my lenses beyond infinity mark on focusing scale? Following recent questions here and here, it sounds like a real usability issue. ...
27
votes
3answers
1k views

What is the difference between a linear and a circular polarizer?

When I bought my polarizer, a friend told me that I should get a circular one, because the linear ones can mess with the autofocus. Is this true? What should each be used for?
4
votes
4answers
1k views

Why does my Nikon D90 autofocus not work in rapid succession?

When photographing candid shots of my children at play with a Nikon D90, I have trouble with the autofocus system. I focus and shoot one shot, great. But a second later another shot opportunity ...
6
votes
3answers
412 views

How does the Nikon D40 decide which focus location to use?

How does the D40 decide which focus location to use? It always seems to choose the wrong focus area.
28
votes
4answers
41k views

What is back-focusing?

What is back-focusing? Is it something I need to be worried about, or can I just live with it? How can I tell if my camera/lens is sufferring from it?
4
votes
2answers
768 views

Force AF assist light on body / flash to come on with Nikon DSLRs?

I have a Nikon D-40 and D-90 with a wide assortment of prime lenses. I like fast primes for low light photography. Some of my lenses are sufficiently old that they do not auto focus at all. Others ...
25
votes
6answers
4k views

Can I damage the focus system by turning the focus ring when the lens isn't mounted?

I have a couple lenses that don't have an internal focusing system, and whenever I want to put them back in my bag, I turn the focus ring to make the lens shorter. I noticed that when the lens is set ...
47
votes
4answers
14k views

What is the best way to micro-adjust a lens?

I have a Canon 7D with a 50mm f/1.4 lens, and I think the auto-focus of the lens is off. How can I test and adjust this reliably? Will this approach work with all of my lenses? If I had a different ...