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Questions tagged [f-stop]

The f-stop of an optical system expresses the diameter of the entrance pupil in terms of the focal length of the lens; in simpler terms, the f-stop is the focal length divided by the "effective" aperture diameter. It is a dimensionless number that is a quantitative measure of lens speed, an important concept in photography.

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Why isn't my F Stop changing on my Nikon D7200?

I can use the dial but the number never goes up or down. It stays at 0. I tried holding down the +/- while turning the front dial and it just adjusts the amount of light coming into the view finder. ...
Hannah Hornberger's user avatar
1 vote
1 answer
753 views

How to keep the aperture of an adapted Nikon G lens open?

I would like to leave my lens fully open all the time without having to find an aperture converter. But other than bluetac I cannot find anything that would attach to my Nikon lens and leave it ...
Jamie Hutber's user avatar
2 votes
6 answers
227 views

Why smaller AoV APS-C has same aperture as larger AoV FF lens?

I am quite confused, FF focal length 50mm f/2.0 has aperture diameter 25mm APS-C lens 50mm f/2.0 has aperture diameter 25mm Then both lenses have same size front glass. However Angle of View for lens ...
LilBro's user avatar
  • 197
2 votes
6 answers
1k views

How do I calculate f/stop change for teleconverter that increases lens magnification?

I'm trying to calculate the f/stop change of attaching a x2 teleconverter to a 80mm f/2.8 lens. In this instance, the teleconverter attaches to the front of the lens, and has a larger opening than the ...
buzz go's user avatar
  • 23
2 votes
3 answers
337 views

For the same FOV and f-stop, will total luminous flux increase linearly with sensor area?

Suppose I have two different cameras, one with a sensor whose area is twice the other's. Further assume the sensors have the same aspect ratio. Suppose I put 35 mm-equivalent lenses on both, thus ...
theorist's user avatar
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-3 votes
3 answers
213 views

How does having a large diameter make the SEL85F1.4 a premium lens?

I have been reading about Focal length and Fast lenses when I came across this lens which has 85mm focal length and F1.4 as FStop. https://www.sony.co.in/electronics/camera-lenses/sel85f14gm Generally ...
Lokesh's user avatar
  • 459
1 vote
2 answers
190 views

How can I compute low light performance for different formats?

How can I compare low light performance for different formats? Are there some standard equations to do this? For example, let's say I want to compare these three camera-lens combinations: Nikon ...
Clickety Ricket's user avatar
4 votes
2 answers
2k views

What's the difference between aperture value and f-number?

In macOS Finder it says a photo taken at f/2.8 has an aperture value of 3. What is an aperture value, and how is it different from f-stop?
clickbait's user avatar
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0 votes
1 answer
333 views

How do you calculate ND filter value of gray sunglasses and the colored sunglasses?

I had the idea of using my sunglasses as ND filter when F/16 didn't help in a beach scene with my MC 2500 but then realized something weird. My green Ray Ban cockpit sunglasses claim to block 85% of ...
Delta Oscar Uniform's user avatar
0 votes
4 answers
315 views

Dynamic range of an HDR photo

I was wondering what is the dynamic range of an HDR photo if the bracketing was set at 2EV? (in F-stops)
Tornado 77's user avatar
3 votes
5 answers
3k views

Do you get more bokeh on a APSC sensor with a full frame 50mm f/1.8 lens or a APSC 30mm f/1.4?

I am trying to compose a detail shot where I want to get as much background blur as possible. I am using Sony a6500 camera (APSC 1.5x crop factor body). I am considering two lenses: Sigma 30mm f/1.4 (...
user5359531's user avatar
5 votes
6 answers
2k views

How many extra stops do monopods offer for tele photographs?

I have often wondered what the purpose of monopods is. It seems to me that they remove only two degrees of freedom out of three possible degrees of freedom of camera shake. And the situation is even ...
juhist's user avatar
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0 votes
3 answers
148 views

Why isn't glass transparency part of the exposure calculation? [duplicate]

The F number is a ratio calculated purely from the focal length of the lens and the size of the aperture. Any light meter talks in terms of F, Shutter, and ISO. Different glass, or just different ...
bmargulies's user avatar
0 votes
2 answers
118 views

Aperature/f stops/lenses [duplicate]

I am interested in landscape photography and a common point I hear thrown around is that a higher aperture (f11-f22) is best for landscape photos. However, every blog, YouTube video and photography ...
Domhnall's user avatar
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2 answers
65 views

How do constant aperture zooms produce identical exposure, even though focal length is larger? [duplicate]

My understanding is that a larger focal length corresponds to a larger working aperture diameter, since the numerator is larger. Why doesn't a larger working diameter correspond to a brighter image? ...
neaumusic's user avatar
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1 answer
257 views

How is the diameter of a non-circular (effective) aperture actually measured?

An f-number is determined as the ratio of the focal length to the diameter of the entrance pupil. But the actual aperture diaphragm is usually not a perfect circle. Its shape is determined by the ...
G_H's user avatar
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2 votes
5 answers
3k views

Why do lower f-stop numbers mean larger apertures? [duplicate]

I thought this would have been asked before but it seems not. I don't understand how f-stops are numbered. From what I read, the lower the f-stop number, the larger the aperture. That is, f/2 is ...
CodyBugstein's user avatar
11 votes
4 answers
3k views

Why are 1/3 stop apertures uneven numbers apart?

Why do 1/3 stop apertures go like 8, 9, 10, 11, 13, 14, 16, 18? There's a difference of 2 between 11 and 13, it goes back to 1 between 13 and 14, and it goes back up to 2.
clickbait's user avatar
  • 1,293
6 votes
3 answers
280 views

How does sensor size affect minimum front element size for a given f-stop and focal length?

Does the sensor size affect the needed size of the front element given a focal length and f-stop? My intuition tells me that a bigger image circle would require a bigger front element to maintain the ...
lijat's user avatar
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2 votes
2 answers
789 views

My Tamron 100-400mm f/4.5-6.3 jumps to f/6.7 beyond 360mm

I got a brand new lens today: a Tamron 100-400mm F/4.5-6.3 Di VC USD. I have mounted it on my Nikon D80. This lens seems to have a problem with its aperture: At 100mm, I can operate from f/4.5 ...
C J Nappoly's user avatar
1 vote
2 answers
295 views

depth of field and f-stop

I have a thorlabs DCC1545M camera. https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=4024&pn=DCC1545M e.g. it has a 1/2 inch format, a sensor size of 6.66mm*5.32mm, with 1280*1024 ...
user3079907's user avatar
3 votes
3 answers
2k views

Confused about T-stop number. Does it account for crop factor?

I understand that a T/stop number deals with how much light is let in, instead of the sensor size vs. aperture like the f/stop number. However, what I haven't found is whether or not that T/stop ...
Tyler VanDenBerg's user avatar
0 votes
1 answer
325 views

What are some general rules for astrophotography?

What are the generally accepted guidelines for iso, f-stop, aperture, etc. that help take better pictures of the stars? In the past I've mostly used a small webcam that fits over the eyepiece of my ...
J Kelly's user avatar
  • 33
1 vote
1 answer
842 views

Will the F-stop Loka or Ajna fit a Macbook Pro 15"?

I'm currently looking at getting a new camera bag that I can use to fit a bit of gear (listed below) and wanted to know if anyone has/had one of these bags and in particular if it will fit a 15" ...
Dale Gribble's user avatar
4 votes
5 answers
597 views

F-stop vs T-Stop - how do I quickly grasp a videographers view of the world?

I'm aware this is flirting with video rather than photography, but the question really relates to how each world can be understood by the other. Very briefly - I am an amateur photographer who ...
Tetsujin's user avatar
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0 votes
1 answer
253 views

How does focus breathing affect DOF?

Like explained in this question Does focus breathing make a lens slower when close focusing? focus breathing does change the effective F-stop. At the same time, the lens behaves, as if it was a ...
user2664856's user avatar
  • 1,150
9 votes
4 answers
1k views

What motivated lens makers to now use 1/3 f-stops rather than say 1/4 or 1/2 stops?

I've noticed that many older lens have just hard f-stops for lens (2, 2.8, etc). However, since the aperture wheel for some is continuous you can "stop" are some arbitrary point and shoot. From my ...
unsignedzero's user avatar
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3 votes
4 answers
1k views

Why does illuminance stay the same for a given f-stop even when focal length changes?

I'm trying to wrap my head around the math/physics of how illuminance on the film/sensor plane remains equal for a given f-number regardless of the focal length of the lens. Since a longer lens will ...
the_meter413's user avatar
20 votes
3 answers
3k views

Why are DSLR lenses measured in F stops instead of T stops?

I understand the difference between f-stop and t-stop, but why are cinema lenses measured in one, and dSLR lenses measured in another?
Barney Chambers's user avatar
0 votes
1 answer
665 views

How to choose f-stop / depth of field? [duplicate]

I am fairly new to photography and I have read many "beginners guides" and watched youtube tutorials. One thing that remains elusive to me is how to properly pick what f-stop to use. I use a 35mm, ...
Alan's user avatar
  • 145
2 votes
2 answers
2k views

Flash guide number f/stop calculation

I have been reading the B&H Speedlight Buyer's Guide. I am confused specifically about the guide number calculation. I understand the principle and how the inverse square law is used. Here is the ...
Albert Savage's user avatar
0 votes
4 answers
195 views

Can cameras set exposure in more precise increments than third stops in automatic exposure mode?

If I shoot in manual I set the exposure to the nearest 1/3 stop. If I use one of the automatic modes does the camera do the same thing or can it set the dependent variable to a resolution finer than 1/...
Alan P's user avatar
  • 261
0 votes
5 answers
14k views

Why doesn't the f-stop on my D7100 change when I hold +/- and change the dial in manual mode?

On my Nikon D7100, the f/stop will not go down from 14 when I hold down the +/- button and turn dial. All I get is a little number below but the photos do not change exposure when I change this number....
Katy Pauls's user avatar
3 votes
1 answer
7k views

Can a lens exist with an f-stop of less than 1? [duplicate]

As I understand it, the F-number of a lens is equal to the aperture diameter divided by the focal length. So f/1 would mean that the aperture is as wide as the lens is long. Question: Is it ...
MathematicalOrchid's user avatar
2 votes
1 answer
997 views

Why don't the Shutter Speed, Exposure Time, Lens Aperture, and F-Number metadata values from my camera make sense?

I was just looking at some digital image properties, and it did not seem to make sense. ...
mcu's user avatar
  • 123
6 votes
3 answers
1k views

Why does Rosco's filter page show that 33% transmission is 1 stop rather than 50%?

I was taught that each stop halves/doubles the light throughput. So one stop up is double as much light, one stop down is half as much light. Now, according to this Rosco table: https://www.rosco.com/...
sharkyenergy's user avatar
  • 1,394
0 votes
1 answer
114 views

Recommended F-Stop for older Canon 35mm F/2 [duplicate]

I have a few year old Canon 35mm F/2 lens (Here it is on Amazon). I've been shooting wide-open, but I realize that doesn't make for the sharpest photos. What would you say would get me the sharpest ...
Isaac Wasserman's user avatar
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 ...
Echo88's user avatar
  • 153
0 votes
1 answer
142 views

Why does Photoshop say the f-stop is f1.6 in the summary but 1.4 in the details at the bottom?

Here is the picture; photo shot in RAW. Why is it that at the bottom it says f1.4, but the summary on top says ...
Brandon's user avatar
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0 votes
2 answers
892 views

How is depth of field usually measured and how can I get depth of field measurements for a lens

I really like a deeply washed out background as a backdrop. I expect using a 35mm film camera that f-stops is inversely related to depth of field. I assume this remains true for compound lenses. But ...
John Robertson's user avatar
2 votes
2 answers
1k views

Does crop factor affect exposure time?

I'm confused on this, even after researching: Given 2 cameras- one full frame with 50mm lens, one Micro Four Thirds (2x crop factor) with 25mm lens, let's pretend the cameras are beside each other, ...
user3833000's user avatar
0 votes
1 answer
524 views

I want to know about the relationship between focal length and aperture [duplicate]

I have Nikon D7000 and I know the basic relation of shutter speed, aperture, and iso. All I want to know is focal length and aperture relation. As I zoom in the camera the f/stop increases (e.g. it ...
hardik's user avatar
  • 1
1 vote
1 answer
459 views

How to photograph oil and pastel art works with DSLR? [duplicate]

I'm using a Nikon D800 with a prime Sigma 50mm f1.4 lens to photograph a selection of artwork for producing an art book. I will shoot in raw format. My questions are: What light source will look ...
WilliamKF's user avatar
  • 1,715
3 votes
2 answers
2k views

How does physical aperture size relate to f/stop?

There are two lenses on the market I am comparing AF Micro-Nikkor 60mm f/2.8D AF-S VR Micro-Nikkor 105mm f/2.8G IF-ED If I use the formula for calculating apertures of both the lenses I will use the ...
Black Dagger's user avatar
3 votes
2 answers
832 views

Why does my lens refocus when the f-stop is changed?

I have a prime Sigma f1.4 50mm lens on my Nikon D90 in P mode and focus mode on a set point of the field and notice that when I am using a tripod and change the f-...
WilliamKF's user avatar
  • 1,715
1 vote
1 answer
124 views

How to shoot the sequence of adjusted exposures wanted for a ColorChecker?

I'm trying to shoot a sequence of photos needed for calibration. As instructed, I'm in manual mode, with fixed ISO 100 (camera dafault), and other values read from the lightmeter ... and now: Can you ...
user37699's user avatar
2 votes
3 answers
1k views

How is the number of stops of benefit provided by VR determined?

I hear people talking about vibration reduction giving you extra 'stops' on a lens, thus giving you extra shutter speed to play with. How do people work this out into an amount of stops? E.g. by ...
connersz's user avatar
  • 1,896
1 vote
4 answers
2k views

What is the equivalent f/stop for 50mm?

If f/8 And Be There is the rule for 35 mm, what is the best f/stop if I am using 50mm? Context: Street Photography Note: Though one can say that "it depends&...
LCJ's user avatar
  • 287
1 vote
1 answer
211 views

what is the barriers of making fast lenses? [duplicate]

I know there are lenses like f/0.7 However as a beginner I'm wondering what's the barrier of making ultra fast lenses like f/0.01 ? Also if lens manufacturers willing to make wide aperture lenses, ...
inckka's user avatar
  • 241
10 votes
4 answers
699 views

Are the aperture, ISO and shutter speed stops perfectly interchangeable?

Imagine you have an scene with shutter speed 1/60, f/8 and ISO 200. Then you change the configuration to get an equivalent exposure: speed 1/120, f/5.6, ISO 200 (plus one stop in speed, minus one stop ...
rodripf's user avatar
  • 225