Speaking of Apertures?
Jun 3, 2021 09:02:16 #
Is there a 'correct' way to describe Aperture adjustments?
If you decrease the aperture you increase the 'f' stop value and conversely when you increase the aperture you decrease the 'f' stop value.
Don't know why, but it's been bugging me for a few days.
If you decrease the aperture you increase the 'f' stop value and conversely when you increase the aperture you decrease the 'f' stop value.
Don't know why, but it's been bugging me for a few days.
Jun 3, 2021 09:08:12 #
gvarner
Loc: Central Oregon Coast
Look at it as a fraction without the numerator. 1/2 is a bigger value than 1/8. F2 is a bigger opening than F8. Is that what you’re after?
Jun 3, 2021 09:09:59 #
John N wrote:
Is there a 'correct' way to describe Aperture adjustments?
If you decrease the aperture you increase the 'f' stop value and conversely when you increase the aperture you decrease the 'f' stop value.
Don't know why, but it's been bugging me for a few days.
If you decrease the aperture you increase the 'f' stop value and conversely when you increase the aperture you decrease the 'f' stop value.
Don't know why, but it's been bugging me for a few days.
Of course there is but even when you say it correctly people can still misunderstand you.
Jun 3, 2021 09:11:15 #
Aperture as a physical attribute is the physical diameter of the lens opening. Open the aperture wider on your lens, just like the pupil of your eyes in the dark, and more light passes through that larger lens opening to reach the sensor. Close the aperture, like your eyes in bright light, and less light passes through the lens opening.
The f-stop (the f-number) is the calculated ratio of lens focal length to effective aperture diameter. A lower f-number denotes a greater aperture opening which allows more light to reach the film or image sensor. The f-number expresses a standard ratio so f/2.8 on a 100mm lens is the same amount of light as f/2.8 on a 20mm lens and the same on a 300mm lens. "Same" is more accurately "roughly the same" as the f-stop calculation includes some rounding of the numbers to get to 1 decimal of precision. The actual millimeter measurement of the openings on the three 20mm vs 100mm vs 300mm lenses will each be different, but the ratio of that specific opening to the focal length of their respective lens yields the same ratio.
You might read the exhaustive details and diagram examples on this wiki page: https://en.wikipedia.org/wiki/Aperture
The f-stop (the f-number) is the calculated ratio of lens focal length to effective aperture diameter. A lower f-number denotes a greater aperture opening which allows more light to reach the film or image sensor. The f-number expresses a standard ratio so f/2.8 on a 100mm lens is the same amount of light as f/2.8 on a 20mm lens and the same on a 300mm lens. "Same" is more accurately "roughly the same" as the f-stop calculation includes some rounding of the numbers to get to 1 decimal of precision. The actual millimeter measurement of the openings on the three 20mm vs 100mm vs 300mm lenses will each be different, but the ratio of that specific opening to the focal length of their respective lens yields the same ratio.
You might read the exhaustive details and diagram examples on this wiki page: https://en.wikipedia.org/wiki/Aperture
Jun 3, 2021 09:12:11 #
When I refer to increasing the aperture, I'm referring to making the opening larger.
It's a reciprocal, that's why the "numbers" go down to increase.
It's a reciprocal, that's why the "numbers" go down to increase.
Jun 3, 2021 09:12:49 #
David Martin
Loc: Cary, NC
John N wrote:
Is there a 'correct' way to describe Aperture adjustments?
If you decrease the aperture you increase the 'f' stop value and conversely when you increase the aperture you decrease the 'f' stop value.
Don't know why, but it's been bugging me for a few days.
If you decrease the aperture you increase the 'f' stop value and conversely when you increase the aperture you decrease the 'f' stop value.
Don't know why, but it's been bugging me for a few days.
Aperture is an inverse or reciprocal. That is, when we say the aperture is "x", we really mean to describe 1/x.
The correct notation for aperture is "F/x". So an aperture with an "F value of 22" is really F/22, which should be thought of as 1/22. As the "F number" increases, the size of the aperture decreases. F/22 is a smaller aperture than F/2.8.
Jun 3, 2021 09:13:17 #
BebuLamar wrote:
Of course there is but even when you say it correctly people can still misunderstand you.
Jun 3, 2021 09:26:01 #
I understand what's happening, the reciprocal bit and all that. I was curious as to how you explain it to others.
I think it came to me, in a roundabout sort of a way, when I read a test on a new Fujinon lens that had an old fashioned aperture ring, manually operated, on it.
I think it came to me, in a roundabout sort of a way, when I read a test on a new Fujinon lens that had an old fashioned aperture ring, manually operated, on it.
Jun 3, 2021 09:36:37 #
John N wrote:
I understand what's happening, the reciprocal bit and all that. I was curious as to how you explain it to others.
I think it came to me, in a roundabout sort of a way, when I read a test on a new Fujinon lens that had an old fashioned aperture ring, manually operated, on it.
I think it came to me, in a roundabout sort of a way, when I read a test on a new Fujinon lens that had an old fashioned aperture ring, manually operated, on it.
You can skip all the math and simply recognize the lower the number, the wider the aperture. The higher the number, the smaller the aperture.
With a small amount of 'math', 1/1 is more than 1/2 is more than 1/4 and so forth. The f-number is just a short hand for the ratio, where if you considered f/2.8 as a ratio like "1/2.8" it's easier to recognize f/2.8 is 'larger' than the ratio of 1/22 (f/22).
Jun 3, 2021 10:08:06 #
"... I was curious as to how you explain it to others..." After many years training computer science for both public and private sector I speak to the level of my students... Here on UHH it is common to speak with authority (not arrogance) so as to contribute to the aggregate knowledge base latent within the forums...
If critical commercial work is involved simply state what aperture you are transitioning to/from...
This way there can be no confusion.
That said... John I would suggest you consider using T-Stops instead... they actually use the "Measured" light passing through the optic... DxOMark uses T-Stops as do cinematographers since they are typically recording video on multiple cameras and this allows for seamless fades/dissolves/transitions...
btw, my Tokina AF 100mm f/2.8 is 2/3's a stop "brighter" than my AF 105mm f/2.8D Nikkor at the same aperture (a.k.a. have two very different T-Stop values)... Simply observe the Histogram and see how it reflects the changes in aperture for various lenses...
Hope this helps Bill...
If critical commercial work is involved simply state what aperture you are transitioning to/from...
This way there can be no confusion.
That said... John I would suggest you consider using T-Stops instead... they actually use the "Measured" light passing through the optic... DxOMark uses T-Stops as do cinematographers since they are typically recording video on multiple cameras and this allows for seamless fades/dissolves/transitions...
btw, my Tokina AF 100mm f/2.8 is 2/3's a stop "brighter" than my AF 105mm f/2.8D Nikkor at the same aperture (a.k.a. have two very different T-Stop values)... Simply observe the Histogram and see how it reflects the changes in aperture for various lenses...
Hope this helps Bill...
Jun 3, 2021 10:22:52 #
gvarner
Loc: Central Oregon Coast
John N wrote:
I understand what's happening, the reciprocal bit and all that. I was curious as to how you explain it to others.
I think it came to me, in a roundabout sort of a way, when I read a test on a new Fujinon lens that had an old fashioned aperture ring, manually operated, on it.
I think it came to me, in a roundabout sort of a way, when I read a test on a new Fujinon lens that had an old fashioned aperture ring, manually operated, on it.
The smaller the number, the bigger the opening. That’s how I explain it to others.
Jun 3, 2021 10:27:33 #
larryepage
Loc: North Texas area
John N wrote:
I understand what's happening, the reciprocal bit and all that. I was curious as to how you explain it to others.
I think it came to me, in a roundabout sort of a way, when I read a test on a new Fujinon lens that had an old fashioned aperture ring, manually operated, on it.
I think it came to me, in a roundabout sort of a way, when I read a test on a new Fujinon lens that had an old fashioned aperture ring, manually operated, on it.
Most (at least many) unmounted lenses will stop down as you turn the aperture ring. The most effective way to explain is to have the person look through an unmounted lens while turning the aperture ring and changing the lens opening. It becomes pretty clear pretty fast. A fast prime lens is best for this. Wide angles are the last choice.
Jun 3, 2021 14:57:06 #
Just think of the f stop number as being the denominator of a fraction.
Jun 3, 2021 15:23:05 #
larryepage
Loc: North Texas area
JRiepe wrote:
Just think of the f stop number as being the denominator of a fraction.
A high percentage of folks don't identify with fractions. Denominators are the primary reason.
Jun 3, 2021 15:47:55 #
I think many of you missed the OP question. The OP understood aperture and the f/number well. His question is how to tell others when he talk about increase/decrease aperture without the person thought it's other way around. For example when one say I want larger aperture he means a larger opening and smaller f/number but the other person may thought it's otherwise.
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