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Conventional and Actual Numeric Values for Aperture, Shutter Speed and ISO
Sep 13, 2021 13:04:47   #
selmslie Loc: Fernandina Beach, FL, USA
 
There are lots of familiar conventional values used in photography. They all were developed originally for film but digital cameras with electronic adjustments have made it easier to become more precise.

You may be familiar with the whole stop aperture values that were engraved on the lens bodies in film days:



The actual values based on the square root of 2 are what the lens actually uses but the conventional values are easier to remember. They are not significantly different. Newer cameras can use 1/3 stop increments and the same table could be created based on the sixth root of 2 but that would be taking it too far since the increments are really precise 1/3 stop increments in the camera.

Shutter speed full stop increments are similar in that the conventional values do not differ materially from the actual values.



Remember that ASA, ISO and DIN were in use long before digital came along. What's more we have always thought of film speed in 1/3 stop increments.



DIN is a logarithmic progression and sequential integers are each separated by exactly 1/3 stop. Corresponding ISO settings are also separated by precise 1/3 stop increments although conventional ISO values have been restated as a series of integers that are easier to remember. As with the other two, there is no material difference in the values and the cameras know how to keep this all tied together.

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Sep 13, 2021 13:51:54   #
tramsey Loc: Texas
 
Good find - Thanks for posting it - Been awhile.

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Sep 14, 2021 08:05:25   #
jerryc41 Loc: Catskill Mts of NY
 
Thanks! Now I can get good pictures! : )

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Sep 14, 2021 09:41:35   #
selmslie Loc: Fernandina Beach, FL, USA
 
tramsey wrote:
Good find - Thanks for posting it - Been awhile.

Thank you.

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Sep 14, 2021 09:46:24   #
selmslie Loc: Fernandina Beach, FL, USA
 
jerryc41 wrote:
Thanks! Now I can get good pictures! : )

It it won't make any difference in your photography.

I just put the tables together as background for a separate discussion about ISO. That's why it's the only table that I showed in 1/3 stop increments.

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Sep 15, 2021 06:26:53   #
jerryc41 Loc: Catskill Mts of NY
 
selmslie wrote:
It it won't make any difference in your photography.



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Sep 15, 2021 21:40:07   #
mundy-F2 Loc: Chicago suburban area
 
selmslie wrote:
There are lots of familiar conventional values used in photography. They all were developed originally for film but digital cameras with electronic adjustments have made it easier to become more precise.

You may be familiar with the whole stop aperture values that were engraved on the lens bodies in film days:



The actual values based on the square root of 2 are what the lens actually uses but the conventional values are easier to remember. They are not significantly different. Newer cameras can use 1/3 stop increments and the same table could be created based on the sixth root of 2 but that would be taking it too far since the increments are really precise 1/3 stop increments in the camera.

Shutter speed full stop increments are similar in that the conventional values do not differ materially from the actual values.



Remember that ASA, ISO and DIN were in use long before digital came along. What's more we have always thought of film speed in 1/3 stop increments.



DIN is a logarithmic progression and sequential integers are each separated by exactly 1/3 stop. Corresponding ISO settings are also separated by precise 1/3 stop increments although conventional ISO values have been restated as a series of integers that are easier to remember. As with the other two, there is no material difference in the values and the cameras know how to keep this all tied together.
There are lots of familiar conventional values use... (show quote)


Nice review. Thank you. I can put away my sliderule.
Mundy

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Sep 15, 2021 21:41:14   #
mundy-F2 Loc: Chicago suburban area
 
selmslie wrote:
It it won't make any difference in your photography.

I just put the tables together as background for a separate discussion about ISO. That's why it's the only table that I showed in 1/3 stop increments.


Nevertheless, good review!
Mundy

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