Interesting article, Andrew, thanks for sharing the knowledge!
I use two apps on my phone when I do long exposures: L(ong)E(exposure) Calculator - straightforward, gives you the exposure times when using various filters, and the more complex Art of Foto app - this one, among other awesome stuff, allows calculations based on specific emulsions on their own or in combination with various filters. Great little tools, always in my pocket.
Thank you for posting this Andrew. I am going to print the Ilford/Kentmere Chart, as I'm sure it will be very useful to keep in my camera bag for future reference.
Great handling of a misunderstood subject. Just two comments, the f2 example is 4000 not 400 of a second, and second the failure varies a lot between different types and makes of film. Foam for example has a high failure rate that needs to be accounted for where as ADOX film is quite short and forgivi of a little error in calculating the error, thus more suitable for long exposures at night. No one chart can cover all film types and speeds, and it is important to know each film failure rate, and have the correct chart for each one.
Thanks for pointing out my typo Phillip, I have amended it. You are quite right about the variations, and I forgot to mention Acros which claims to not need reciprocity failure compensation up to 2 minutes.
The calculator on a smartphone can be useful as a way of making the calculations for Ilford films in the field. Turn the phone to landscape mode and the calculator becomes a scientific calculator, including the "power" function.
I've talked about reciprocity failure for years but you've just explained what it actually meant. Maybe I should talk less. Thanks Andrew!
Thanks Vic.
Interesting article, Andrew, thanks for sharing the knowledge!
I use two apps on my phone when I do long exposures: L(ong)E(exposure) Calculator - straightforward, gives you the exposure times when using various filters, and the more complex Art of Foto app - this one, among other awesome stuff, allows calculations based on specific emulsions on their own or in combination with various filters. Great little tools, always in my pocket.
The Art of Foto has been super helpful with my first forays into LF photography.
Thank you for posting this Andrew. I am going to print the Ilford/Kentmere Chart, as I'm sure it will be very useful to keep in my camera bag for future reference.
Thanks again.
Difficult subjects with great titles: reciprocity failure(s).
Great handling of a misunderstood subject. Just two comments, the f2 example is 4000 not 400 of a second, and second the failure varies a lot between different types and makes of film. Foam for example has a high failure rate that needs to be accounted for where as ADOX film is quite short and forgivi of a little error in calculating the error, thus more suitable for long exposures at night. No one chart can cover all film types and speeds, and it is important to know each film failure rate, and have the correct chart for each one.
Thanks for pointing out my typo Phillip, I have amended it. You are quite right about the variations, and I forgot to mention Acros which claims to not need reciprocity failure compensation up to 2 minutes.
The calculator on a smartphone can be useful as a way of making the calculations for Ilford films in the field. Turn the phone to landscape mode and the calculator becomes a scientific calculator, including the "power" function.
Thanks kevin.