All Questions
69
questions
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....
- 32k
36
votes
4
answers
8k
views
How do you find out the "sweet spot" of a lens?
I've tried googling this, but have never found a satisfactory answer.
I've heard the term "sweet spot" thrown around by some photographers to mean the f-stop of a lens which results in the highest ...
- 1,919
46
votes
7
answers
14k
views
How do constant aperture zoom lenses work?
Cheaper zoom lenses usually are faster at the wide end and slower at the long end (for example, the $150 Canon EF-S 18-55mm f/3.5-5.6). More expensive constant-aperture zoom lenses have the same ...
- 5,088
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 ...
- 1,097
22
votes
2
answers
5k
views
Why do zoom lenses and compact cameras have varied maximum aperture across the zoom range?
Why does a camera's maximum (allowed) aperture get smaller when you increase its zoom?
- 641
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?
- 363
12
votes
7
answers
109k
views
Why is my Nikon 50mm f/1.8 giving me an fEE error?
I have a AF Nikkor 50mm f/1.8. When I have the aperture setting on the lens to 22 I can take photos. But when I change the dial to anything other than 22(lowest f/stop) then I get a flashing fEE ...
- 579
15
votes
3
answers
2k
views
How do zoom lenses restrict their widest aperture at the telephoto end?
Does the aperture ring lock the apertures beyond, say 5.6 at length lens's telephoto end?
Does the lens introduce an obstacle to the aperture ring so the lens can't be opened anymore beyond the ...
- 1,515
5
votes
2
answers
4k
views
Is the size of the entrance pupil the same as the size of the effective aperture?
I understand that the entrance pupil is the image of the aperture as seen from the front of the lens. However, is the size of the entrance pupil the same as the size of the effective aperture? In ...
- 265
70
votes
12
answers
93k
views
Is there a noticeable difference between 1.8 and 1.4 prime lenses?
I have been shopping around for a prime lens for my Nikon D50. I noticed that the 1.8 is hundreds of dollars cheaper than the 1.4 AF-S. What will I gain for that cost difference? Is it really ...
- 1,413
12
votes
6
answers
8k
views
What are the theoretical minimum and maximum apertures?
Is there such a thing as a maximum aperture that a lens can be open to? What about a minimum aperture that it can be closed to? Do these concepts even make any sense? Is there a lens with the ...
- 673
31
votes
3
answers
8k
views
Why do wide angle prime lenses have relatively small apertures?
I've noticed that many of the wide angle prime lenses (at least for Canon) have somewhat smaller apertures than their normal or telephoto counterparts. E.g. the regular Canon 24mm prime is f/2.8 while ...
- 4,655
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 ...
- 3,350
11
votes
8
answers
9k
views
What is the fastest lens available for a DSLR?
I've seen references to f1.2 lenses. I was wondering, are there any faster lenses available for a DSLR mount?
9
votes
3
answers
6k
views
What are the advantages of a lens having a fixed maximum aperture?
What are the advantages of a lens having a Fixed Maximum Aperture? Previous answers have indicated that "pros tend to want constant apertures in zoom lenses".
While in general lenses with a fixed ...
- 2,641
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