All Questions
166
questions
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{...
- 297
1
vote
2
answers
131
views
When stopped down, does light still pass through all of a glass element behind the aperture blades
When you stop down and look through the lens, the iris (circle of light) gets smaller. Does this mean that light only passes through the middle of each lens element behind the aperture blades? What ...
- 703
0
votes
2
answers
287
views
zoom or aperture which one decreases DoF?
When I want to decrease my DoF and have Bokeh in my photos, I always stuck between choosing either opening the aperture or zooming.
Should I start zooming or should I decrease the aperture?
Edit: I'...
- 163
1
vote
3
answers
8k
views
What is the sweet spot of the Canon's 18-55mm IS STM lens?
I'm plannning to photograph negative film like this. And I would like to know what would be the sweet spot of my lens to achieve best sharpness possible, what f stop and at what mm I should be ...
- 459
2
votes
5
answers
2k
views
Does a full frame lens require more light on a crop body? [duplicate]
When using a full frame lens on a crop body, does the lens require more light?
If I use an f/2.8 full frame lens on a crop body, does it become an f/4.2 (*1.5)?
- 145
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
3
votes
1
answer
322
views
Can Nikon PK-11a extension tubes be used with G lenses, keeping aperture control?
I own a D3200 and 3 G lenses (kit lenses + 35mm f1.8G) and I was wondering if I could use an extension tube PK-11a with them keeping aperture control functional. At Nikon website seems to say no, but ...
- 33
1
vote
3
answers
3k
views
What factors make a lens brighter? [duplicate]
Let's say I have two lenses of 50mm, one with maximum aperture f/1.8 and another with f/1.4.
I understand that when using maximum aperture, for the latter lens more light will get to the film or ...
- 533
1
vote
2
answers
586
views
Are there lenses f/1 or wider that work on EF or E-mount?
Which lenses have apertures at f/1 or better, and work on cameras like the 6D or A7?
In Sony's case, an adapter is acceptable.
- 739
0
votes
6
answers
320
views
Is the wide aperture and bokeh of a 50mm prime more important than getting to the 70-90mm range for portraits?
I've a Pentax K-30 with the following lens:
Pentax-M 50mm 1.7 manual focus
Tamron 17-50mm 2.8 autofocus
Pentax 55-300mm 4-5.6 autofocus
Considering that :
Pentax 50mm has the nicest bokeh and ...
- 461
6
votes
2
answers
1k
views
How does sensor size affect the brightness of an image given the same field of view and aperture?
Lets say we have two image sensors, each one with 1MPixel resolution but differing in size. The first sensor has the size 1/3", the other one 1".
Each sensor is equipped with a suitable lens (for the ...
- 153
2
votes
1
answer
969
views
Why don't all zoom lenses have variable f-numbers? [duplicate]
As I understand it, the f-number is a ratio between the focal length and the aperture diameter. A zoom lens can change focal length, but shouldn't the maximum aperture be a fixed size? If so, that ...
- 123
5
votes
1
answer
483
views
What prevents a f/1.8, 24 mm - 70 mm or similar range zoom lens from being made? [duplicate]
I see that it is common to have professional grade lenses such as 24-70mm lenses made at f/2.8. After using a 50mm/1.8, I was wondering what would prevent a more versatile zoom lens to be made that ...
- 249
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:...
- 239
1
vote
1
answer
358
views
How can I set the aperture in A mode with a D lens on my Nikon D90?
I use Nikon 35mm f/2d lense on my Nikon D90 but I am unable to change aperture of lens.
I have the aperture on the lens set to f22 and locked, I can change aperture with the buttons and the change is ...
- 13
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