Exposure

Likesithot · Nov 8, 2022

Is there a more intuitive system for f stop and shutter speeds? Obviously confusing that smaller f stops (by number) let in more light and larger 1/2,000 sec ( compared to 1/125 sec.) are less time aperture is open. What about lens speed/35 mm equivalent. Is there a system not necessarily related to historical uses?

Gam3r01 · Nov 8, 2022

Well, both fstops and shutter speed are measured as fractions, so that explains the larger numbers being "smaller".

If you think of fstops as a fraction of 1, they make a bit more sense. 1/2 is much larger than 1/8, for example. So f/2 lets is more light than f/8.

Shutter speeds are also either whole or fractions of a second, depending on duration. Those make much more sense than fstops as well, since its a direct measurement of time. The other option would be decimal format, which would honestly be worse.

sybersitizen · Nov 8, 2022

Likesithot said:
Is there a more intuitive system for f stop and shutter speeds?

Nope.

Likesithot said:
Obviously confusing that smaller f stops (by number) let in more light ...

How long does that confuse people? I think most catch on pretty quick, especially when the terms are properly expressed as fractions: f/2, f/4, f/8, etc. We're taught at an early age that something divided by 2 is larger than the same thing divided by 8.

Likesithot said:
and larger 1/2,000 sec ( compared to 1/125 sec.) are less time aperture is open.

1/2,000 has always been smaller than 1/125, not larger. One alternative would be to express the figures as 0.5 milliseconds and 8 milliseconds. Would you call that more intuitive?

Likesithot said:
What about lens speed/35 mm equivalent. Is there a system not necessarily related to historical uses?

Any number of systems can be invented, but they'll all have certain drawbacks. The current ones are related to historical uses because they've been working satisfactorily for so long.

Leonard Migliore · Nov 8, 2022

Likesithot said:
Is there a more intuitive system for f stop and shutter speeds? Obviously confusing that smaller f stops (by number) let in more light and larger 1/2,000 sec ( compared to 1/125 sec.) are less time aperture is open. What about lens speed/35 mm equivalent. Is there a system not necessarily related to historical uses?

Yes. Use a phone.

JustUs7 · Nov 8, 2022

Should consider looking up an exposure chart where all exposure times (shutter speeds) and f-stops are laid out clearly. I found that helpful early on.

Mark S Abeln · Nov 8, 2022

The exposure system is long established and has been standardized to use particular values for f/stop and shutter speed. I don’t see it changing now, the time has passed; it’s a part of tradition now.

The most helpful tool for me was an old hand held light meter:

You press a button and it measures the amount of light either falling on the scene, or reflected by the scene. You turn a dial to match the meter reading, and it gives you all of the combinations of shutter speed and f/stop that gives you the same exposure.

But feel free to propose an alternate system.

--

The Refracted Light

A website about the Art and Science of Photography

$therefractedlight.blogspot.com$ therefractedlight.blogspot.com

Djehuty · Nov 8, 2022

Likesithot said:
Is there a more intuitive system for f stop and shutter speeds? Obviously confusing that smaller f stops (by number) let in more light and larger 1/2,000 sec ( compared to 1/125 sec.) are less time aperture is open. What about lens speed/35 mm equivalent. Is there a system not necessarily related to historical uses?

Just shoot on auto if its confusing.

Gato Amarillo · Nov 8, 2022

The F number thing can be a bit confusing at first, but it's not too difficult to get the basics. After that it's pretty simple.

It was probably a little easier back when lenses and shutter speed were marked in full stops (doubling or halving exposure), but it's not too hard even now when one click on one dial is equivalent to one click on the other -- or on the ISO, which didn't come into play so much until recently.

Maybe there is a simpler or more intuitive way, but I don't see it, And if there is it could take a generation or longer to put it into general practice.

Gato

Tom Axford · Nov 8, 2022

The f-stop or f-number (often called simply the aperture) is actually the focal length divided by the diameter of the entrance pupil. The entrance pupil is the hole that you see if you look into the front of the lens when light shines into the back of the lens.

From the left: 12mm f/2.8 (entrance pupil = 4mm), 45mm f/1.8 (ep=25mm), 75mm f/1.8 (ep=42mm), 25mm f/1.4 (ep=18mm), 9mm f/4 (ep=2mm)

The size of the entrance pupil determines the amount of light entering the lens.

However, the brightness of the image depends not only on amount of light entering the lens, but also on how large the image (of a particular object) is. The size of the image is proportional to the focal length.

So the brightness of the image depends on the entrance pupil divided by the focal length, which is simply the inverse of the f-number. This is why the f-number of the lens is given rather than its entrance pupil.

Nigvo · Nov 8, 2022

It is the most logical system that there is, based on very simple primary school arithmetic.

The shutter speed is described as a simple fraction of a second, by the time the shutter is open, which is much clearer than let's say seconds and milliseconds.

Aperture is described by the ratio of focal length to effective aperture diameter, again quite logical and useful.

It is a system that has worked well for generations of photographers and ten minutes of study will make everything clear and logical. Knowing how to use the aperture, shutter speed and ISO relationship will take anybody's photography to a better level.

“Everyone sees what you appear to be, few experience what you really are.”
- Niccolo` Machiavelli.

NIGEL'S RAMBLES

nigelvoak.blogspot.com

grsnovi · Nov 8, 2022

Mark S Abeln said:
it gives you all of the combinations of shutter speed and f/stop that gives you the same exposure.

Which is essentially what you get in either A or S mode, one allows you to select the shutter and it selects the aperture while the other allows you to select the f-stop and it selects the shutter.

It would seem basic to me that a total newbie would shoot in either of those before tackling full manual mode where you need to have some idea?

grsnovi · Nov 8, 2022

Nigvo said:
It is the most logical system that there is, based on very simple primary school arithmetic.

...but it's not like you have to do arithmetic!!

I initially didn't even reply to this because frankly I didn't understand the OP's question (if there is even a question embedded in that first post).

a_c_skinner · Nov 9, 2022

The present system is actually very simple with one proviso. You need to learn the physics/maths behind it. Learning the very basics will serve anyone well as they take photos. A basic book will take up a few £/$ and a few evenings and both will be repaid time and again.

Nigvo · Nov 9, 2022

a_c_skinner said:
The present system is actually very simple with one proviso. You need to learn the physics/maths behind it. Learning the very basics will serve anyone well as they take photos. A basic book will take up a few £/$ and a few evenings and both will be repaid time and again.

Well said. I get the impression that many do not want to do a minimum amount of study to understand how to get the best out their camera.

I have understood why so many find the concept and relationship between shutter speed and aperture so difficult.

AlbertTheLazy · Nov 9, 2022

I can't think of a more 'intuitive' way of expressing exposure time than as a fraction of a second. Just don't call it 'speed'.

For the aperture there have been a number of attempts, mostly assigning an arbitrary number to a particular f:stop as a base line.

For example, US (Uniform System, IIRC), used on many Kodakcameras about 100+ years ago, based its sequence on f:4, which means a modern f:2 lens would need to be marked 0.25.

Some other cameras were just marked 1,2,3,4.... without reference to the actual light passing capacity of the lens

Loading…

en.m.wikipedia.org

All this was back in the day when light meters did not exist and film sensitIvities were not accurately measured.

emax · Nov 9, 2022

Gam3r01 said:
Shutter speeds are also either whole or fractions of a second, depending on duration. Those make much more sense than fstops as well, since its a direct measurement of time. The other option would be decimal format, which would honestly be worse.

One could use microseconds (μs), where 1/1000 s = 1 μs, 1/500 s = 2 μs, etc.

Expressing 1/3 s as 333 μs might be a bit awkward, though, and shutter speeds faster than 1/1000 s would become decimals or fractions again.

Note: I posted this before noticing that at least one previous poster (sybersitizen) had already discussed the same thing.

Quarkcharmed · Nov 9, 2022

Nigvo said:
It is the most logical system that there is, based on very simple primary school arithmetic.

It's not very sophisticated mathematically, but far from being very simple.

Member said:
The shutter speed is described as a simple fraction of a second, by the time the shutter is open, which is much clearer than let's say seconds and milliseconds.

The shutter speed has a confusing name because it's not 'speed' but 'time'. It's not described as a fraction of a second, it's defined as time for the shutter to open and close. It's the same as exposure time.

Now the OP's question implies the OP thinks 1/2000 is a larger number than 1/125. The is where the misunderstanding stems from.

Member said:
Aperture is described by the ratio of focal length to effective aperture diameter, again quite logical and useful.

So from your definition, aperture is focal length divided by aperture.

What you described is not aperture but 'f-number'. F-number is what follows 'f/', for example, when you see 'f/2.8', 2.8 is the f-number.

Also it's not an 'effective' diameter, it's the diameter of the entrance pupil, here's a brief explanation https://en.wikipedia.org/wiki/Entrance_pupil

a_c_skinner · Nov 9, 2022

I think 1/1000 is a 1 ms not 1 μs.

Nigvo · Nov 9, 2022

Quarkcharmed said:
Nigvo said:

It is the most logical system that there is, based on very simple primary school arithmetic.

Click to expand...

It's not very sophisticated mathematically, but far from being very simple.

In what way. Anybody who cannot understand what a fraction of a second is, must be seriously lacking in basic numeracy.

The shutter speed is described as a simple fraction of a second, by the time the shutter is open, which is much clearer than let's say seconds and milliseconds.

Quarkcharmed said:
The shutter speed has a confusing name because it's not 'speed' but 'time'. It's not described as a fraction of a second, it's defined as time for the shutter to open and close. It's the same as exposure time.

Semantics like many other things. Easily resolved by reading a basic photography text.

Quarkcharmed said:
Now the OP's question implies the OP thinks 1/2000 is a larger number than 1/125. The is where the misunderstanding stems from.

Quarkcharmed said:

Aperture is described by the ratio of focal length to effective aperture diameter, again quite logical and useful.

Click to expand...

So from your definition, aperture is focal length divided by aperture.

What you described is not aperture but 'f-number'. F-number is what follows 'f/', for example, when you see 'f/2.8', 2.8 is the f-number.

It is the F number on the lens which is useful.

Quarkcharmed said:
Also it's not an 'effective' diameter, it's the diameter of the entrance pupil, here's a brief explanation https://en.wikipedia.org/wiki/Entrance_pupil

Djehuty · Nov 9, 2022

Nigvo said:
It is the most logical system that there is, based on very simple primary school arithmetic.

The shutter speed is described as a simple fraction of a second, by the time the shutter is open, which is much clearer than let's say seconds and milliseconds.

Aperture is described by the ratio of focal length to effective aperture diameter, again quite logical and useful.

It is a system that has worked well for generations of photographers and ten minutes of study will make everything clear and logical. Knowing how to use the aperture, shutter speed and ISO relationship will take anybody's photography to a better level.

“Everyone sees what you appear to be, few experience what you really are.”
- Niccolo` Machiavelli.
https://nigelvoak.blogspot.com/

Y'all making it more confusing.

Exposure

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