All Questions
166
questions
2
votes
2
answers
75
views
Do non-constant aperture zoom lenses vary aperture when zooming, when the aperture is not set to wide-open?
I am an experienced amateur photographer and videographer using a Sony a7sII with a Sigma 28-300mm f3.5-6.3 hyperzoom lens for a music video shot. I notice that when I test the shot zooming out all ...
2
votes
1
answer
3k
views
How to fix stuck aperture?
I have a Micro-Nikkor 55 mm 1:2.8 lens. The aperture appears to be stuck. Is it worth trying to repair the lens? Are there any good guides for disassembling the lens?
- 542
0
votes
4
answers
96
views
Brightness of a full frame lens mounted on aps-c vs mounting an identical native aps-c lens [duplicate]
I am a bit confused about the effect of using a full-frame lens on a aps-c camera on the brightness of the resulting image.
Lets say we have two lenses:
A full frame 50mm f2 lens
An aps-c 50mm f2 ...
- 39.4k
0
votes
2
answers
2k
views
How do I correctly convert from aperture diameter into f-stops?
I'd like to know whether it's possible to convert the radius of the focal point into f-stops properly. The following equation illustrates that the diameter is dependent on the f-stop:
$$ \text{...
- 33.1k
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 ...
- 33.1k
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 ...
- 33.1k
5
votes
3
answers
2k
views
Can I force the aperture to stay open on macro lens?
I have a sigma 180mm f/2.8 lens, which I bought because it was the largest aperture I could find that focuses around 0.5m See this question for why this was important.. Upon arrival, however, the lens ...
- 33.1k
0
votes
4
answers
3k
views
Can aperture be changed in aperture mode even with a constant maximum aperture lens?
I am new to non-auto mode.
If I have a fixed aperture lens with f/2.8 16–35 mm. Does this mean I cannot change the aperture to f/4 or f/5 on my camera because the lens only supports f/2.8?
Is the f/2....
- 33.1k
2
votes
3
answers
440
views
Is diffraction limited aperture independent of lens?
I have always understood diffraction limited aperture as a property of the camera and its sensor, not of the lens. The camera has a certain sensor size and a certain megapixel count, which together ...
CommunityBot
- 1
2
votes
2
answers
269
views
Tamron SP 500mm mirror lens changing aperture and DOF
Please help me understand. I have the above F8 mirror lens. I know the difference between F stop and T stop. I have measured this T stop experimentally it is higher than F8. The DOF feels very narrow ...
- 27k
5
votes
3
answers
1k
views
Is aperture the same on different format of lenses?
I have just acquired a large format lens (a Schneider-Kreuznach Angulon 1:6,8/90) for the first time, coming from 35mm and medium format, and I am a bit puzzled by its aperture.
I want to make sure I ...
- 39.4k
3
votes
4
answers
13k
views
How to remove oil from aperture blades?
If you go on ebay or other second hand places, you'll see a fair amount of lenses that have oil on the aperture (particularly on older lenses).
I've done some reading and it looks like this oil is ...
6
votes
3
answers
6k
views
What lenses can produce a clean starburst effect?
I have seen several examples of a beautiful lens effect, naturally due to a stopped down aperture, but not like a lens star I have managed to create myself - it is so clean. Here is an example:
https:...
- 11
2
votes
4
answers
670
views
What are the technical reasons to design lenses with oddly shaped apertures?
Some lenses have oddly shaped apertures, like star or shuriken shaped. It seems to be intentional since making "normal" rounded or polygonal apertures is fairly simple (as I have observed while ...
- 71
17
votes
7
answers
1k
views
Does lens speed still increase meaningfully when the physical aperture is larger than the sensor size?
This question came to me this morning, thinking about 50mm lenses. I have the Pentax 50mm f/1.7 (manual) and it's a very nice lens, but would be considered (relatively) slow on 35mm film, and many ...
- 22.1k
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