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57 votes
9 answers
144k views

What is aperture, and how does it affect my photographs?

How does aperture affect my photographs? Why should I care about the aperture with which a photo was taken?
Dan McClain's user avatar
  • 2,087
68 votes
4 answers
153k views

What does f-stop mean?

What does f-stop mean? Is it the same thing when people say "2 stops" for example?
matt burns's user avatar
  • 6,036
32 votes
2 answers
27k views

What is T-number / T-stop?

Usually, when discussing aperture of a lens, F-stop and F-number are used for quantifying. But some photographers, and especially videographers, also mention T-stop. The concept and numbering used (e....
Imre's user avatar
  • 32k
23 votes
7 answers
14k views

How can aperture be f/11 on a lens with an aperture range designation of 3.5-5.6?

I made a series of outdoor shots with Nikon D5000, with the 18-55mm 1:3.5-5.6G VR kit lens. On some shots, I see in the EXIF info f/11, and in another shot, f/9. How can that be, that the f-number ...
Andrei's user avatar
  • 1,097
26 votes
4 answers
6k views

What is a "fast" lens?

I've been reading lots of camera reviews lately and have ran across several references to "fast" lenses. What exactly is a fast lens and what are its advantages compared to other lenses?
Patrick Ritchie's user avatar
14 votes
6 answers
12k views

What is the meaning of "stopped down"?

Was reading this answer (emphasis mine): It also tells us that the lens was stopped down, as if it were wide open there would be no corners to cause diffraction, regardless of the number of ...
Billy ONeal's user avatar
  • 3,350
12 votes
3 answers
9k views

Why don't comparisons of aperture take sensor size into account?

When one compares focal length, many times we use the 35mm equivalent length. A 50mm lens on an APS-C sensor camera(1.6x) would be a 80mm equiv. length on a full frame camera. But when we state the ...
dpollitt's user avatar
  • 46.6k
19 votes
5 answers
3k views

What are the benefits of the classic f-number scheme?

Classic ƒ numbers are entrance pupil diameter as a fraction of focal length. This seems like a slightly strange choice as exposure is proportional to area rather than diameter. Naively I would think ...
Mr.Wizard's user avatar
  • 416
12 votes
4 answers
15k views

What is a "small" aperture?

It happens a lot. People refer to the aperture being small (or big!). By default does this imply a small opening of the iris (literal aperture), or a small f-value (how the aperture is measured, for ...
James's user avatar
  • 2,724
10 votes
3 answers
2k views

What is the technical name for a zoom lens which has a fixed maximum aperture?

What is the technical name for a lens which has the same maximum aperture throughout the entire zoom range?
Aquarius_Girl's user avatar
6 votes
4 answers
4k views

What are the types of aperture blades?

The Canon EF 24-105mm f/4 L USM IS lens has rounded aperture blades. What other types of aperture blades are there, and what are the advantages and disadvantages of each of them? Is the aperture ...
K'''s user avatar
  • 6,497
2 votes
3 answers
3k views

What does "maximum aperture" mean in a camera spec? Where can I get the full aperture range?

I own a Canon S95, and am considering getting a newer model (e.g. Canon S110 or S120), and I'm comparing the specs. According to DPReview.com, the S95 has a maximum aperture of F2.0-F4.9, and the S110 ...
Jason's user avatar
  • 635