What is EI?

[ErinHilburn]

blind luck, I have a knack for night photography when it rains.

 

[Helen B]

“So to summarise, what effect can I expect on skies if I lower box speed?”

Pentaxuser,
This is something that is best answered by testing in the typical conditions you are referring to, using your normal printing method. Colour print materials are usually designed to respond to a fixed density range on the negative (and that density range is only a portion of the potential negative density range), so doing a straight print to capture shadow details is likely to burn out the highlights (in the print) and vice-versa. It’s worth finding out, by personal experiment, how your particular materials and technique respond to changes in exposure: how it affects the different representations of shadows, mid-tones and highlights.

If the print material were capable of responding to the entire density range that negative film is capable of having, the result with most scenes would look very flat. Tonal compression equivalent to thirteen stops of scene brightness condensed into seven stops of image brightness on the paper. So, without resorting to unmentionable techniques, dodging and burning, or masking are necessary. Unless you fix it at the taking stage with a grad.

“Wow!! you get not one but two professors teaching a 6 week B&W course!”

Sounds very impressive. ‘Professor’ means very different things in US and UK English: in the UK a professor is typically a department head at a university and thus rarely to be caught teaching, or doing anything else that even faintly resembles real work. In the US a professor can be the equivalent of a teacher in the UK.

“f/1.4 lets 2.04086 times as much light through as f/2.”

Ed,
Small nitpicking point, but the f-numbers that aren’t equal to two raised to an integer power (ie 0.5, 1, 2, 4, 8, 16 etc) are quoted to two significant figures, and the last one may not be correct (eg 5.6 should be 5.7 and 22 should be 23 but it doesn't really matter) so calculations to more than two sig figs are a bit meaningless. Example: ‘1.4’ is the shortened form of the square root of 2, so it is 1.41421 if you want six figure accuracy. Not that aperture settings are ever likely to be anywhere near that accuracy, of course.

Best,
Helen
(and thanks to Mick for the kind comment)

 

[pentaxuser]

“So to summarise, what effect can I expect on skies if I lower box speed?”

Pentaxuser,
This is something that is best answered by testing in the typical conditions you are referring to, using your normal printing method. Colour print materials are usually designed to respond to a fixed density range on the negative (and that density range is only a portion of the potential negative density range), so doing a straight print to capture shadow details is likely to burn out the highlights (in the print) and vice-versa. It’s worth finding out, by personal experiment, how your particular materials and technique respond to changes in exposure: how it affects the different representations of shadows, mid-tones and highlights.

If the print material were capable of responding to the entire density range that negative film is capable of having, the result with most scenes would look very flat. Tonal compression equivalent to thirteen stops of scene brightness condensed into seven stops of image brightness on the paper. So, without resorting to unmentionable techniques, dodging and burning, or masking are necessary. Unless you fix it at the taking stage with a grad.

“Wow!! you get not one but two professors teaching a 6 week B&W course!”

Sounds very impressive. ‘Professor’ means very different things in US and UK English: in the UK a professor is typically a department head at a university and thus rarely to be caught teaching, or doing anything else that even faintly resembles real work. In the US a professor can be the equivalent of a teacher in the UK.

“f/1.4 lets 2.04086 times as much light through as f/2.”

Ed,
Small nitpicking point, but the f-numbers that aren’t equal to two raised to an integer power (ie 0.5, 1, 2, 4, 8, 16 etc) are quoted to two significant figures, and the last one may not be correct (eg 5.6 should be 5.7 and 22 should be 23 but it doesn't really matter) so calculations to more than two sig figs are a bit meaningless. Example: ‘1.4’ is the shortened form of the square root of 2, so it is 1.41421 if you want six figure accuracy. Not that aperture settings are ever likely to be anywhere near that accuracy, of course.

Best,
Helen
(and thanks to Mick for the kind comment)

Thanks Helen. Sounds as if a ND grad is favourite. However I must try the same scene at different speeds to check the effect first. Nothing ventured nothing gained as they say.

Pentaxuser