Free FomaPan Reciprocity IOS APP

[ian barber]

For many years, I have found myself returning to Fomapan black and white films, so I decided to create a simple iOS app specifically for Fomapan users.
There are no unnecessary features or complicated settings. It is simply designed to get the job done.

The app calculates reciprocity corrected exposure times for Fomapan 100, 200 and 400, making long exposure photography much easier without needing to consult charts or work through the calculations manually.

Just choose your film, enter the metered exposure time, and the app gives you the corrected exposure.

It is now available on the Apple App Store.
https://apple.co/4gQtUF9

 

[Vieri]

Hello Ian,

thank you very much, that is a wonderful tool to have! It looks like you used the Te=Tm[1.5(logTm)^2+4.5(logTm)+3] formula and twicked the results a little (a few seconds here and there)?

When I started using Foma 200, I created for myself a spreadsheet (attached here) with three columns; one used that formula, the second the 1.43xx factor I found somehwere online and the third an average of the two.

The numbers in your app look very close to the first column in my spreadsheet, I'd be curious whether the small differences are adjustments you made out of direct experience.

As well, I noticed that you used full stops all the way; perhaps, past 1 sec you could add at least thirds of a stop? In my experience, those are pretty useful when using a film with such a strong reciprocity, and are difficult to figure on the fly given the very non-linear nature of Fomapan 200 Creative's response.

Thanks again! Best regards,

Vieri

 

[ian barber]

It looks like you used the Te=Tm[1.5(logTm)^2+4.5(logTm)+3] formula

The above formula is different to the one I used in the App.

past 1 sec you could add at least thirds of a stop?

I can see the benefit for this so I will add it in the next release

Ian

 

[ian barber]

I have submitted Version 1.1 to Apple to review.
Version 1.0 took 9 days to get approved so will just have to wait and see if they approve 1.1

What's New

• Added selectable full, half and third-stop exposure intervals
• Added filter compensation for ND and coloured filters
• Added a built-in exposure countdown timer
• Added warnings when calculations exceed published data
• Added an About section and privacy-policy link
• Refined the interface and improved usability

 

[Flack]

I shoot a lot of Formapan when I can get out with my camera, so this should be handy, thanks Ian.

 

[Vieri]

I have submitted Version 1.1 to Apple to review.
Version 1.0 took 9 days to get approved so will just have to wait and see if they approve 1.1

What's New

• Added selectable full, half and third-stop exposure intervals
• Added filter compensation for ND and coloured filters
• Added a built-in exposure countdown timer
• Added warnings when calculations exceed published data
• Added an About section and privacy-policy link
• Refined the interface and improved usability


View attachment 21716

Thank you Ian! Will keep an eye for the upgraded version.

Best regards,

Vieri

 

[ian barber]

Thank you Ian! Will keep an eye for the upgraded version.

Best regards,

Vieri

Version 1.1 is now live

 

[Vieri]

Version 1.1 is now live

I checked it out, adding the timer is a great idea!

Nice to have the filters as well, although not as fundamental as the timer in my opinion (people using film are normally used to calculate filter adjustments), but still a cool extra. I think that having thirds of a stop in the Exposure adjustment for ND filter to be overkill, since all ND filters are rated in single stops and it makes it more cumbersome to move between different filters. Also for colour filters, the most you need is 1/2 stop precision, 1/3 is overkill.

Also, but this is just cosmetics, I don't know if the numbers in the "metered exposure" selectors are calculated by the app or if you have any control over them, but you might want to revise them, e.g. in the 1/3 stop selector after 2 you got 2.5 sec (should be 2.6).

Hope this helps, best

Vieri

 

[Vieri]

The above formula is different to the one I used in the App.

Which formula did you use, if I may ask?

I can see the benefit for this so I will add it in the next release

Ian

You are welcome.

Best,

Vieri

 

[ian barber]

but you might want to revise them, e.g. in the 1/3 stop selector after 2 you got 2.5 sec (should be 2.6).

One-third stop above 2 seconds is:
2 × 2^(1/3) = 2.5198 seconds

 

[Vieri]

One-third stop above 2 seconds is:
2 × 2^(1/3) = 2.5198 seconds

Except, your scale is in seconds, not stops. So, if you need to divide the interval between 2 and 4 seconds in three parts, each one needs to be spaced 0.666666666 (periodic) secs.

Just trying to help here, sadly your attitude doesn't make me feel too inspired to keep doing it. Best of luck with the app!

Best regards,

Vieri

 

[ian barber]

Except, your scale is in seconds, not stops. So, if you need to divide the interval between 2 and 4 seconds in three parts, each one needs to be spaced 0.666666666 (periodic) secs.

Just trying to help here, sadly your attitude doesn't make me feel too inspired to keep doing it. Best of luck with the app!

Best regards,

Vieri

Photographic stops are logarithmic, not linear. A one-stop increase doubles the exposure time, so each third-stop multiplies the time by the cube root of 2 (2^(1/3)), rather than adding a fixed number of seconds.

Starting at 2 seconds, this gives approximately 2, 2.52, 3.17 and 4 seconds, conventionally rounded to 2, 2.5, 3.2 and 4 seconds. Dividing the interval into 0.667-second steps divides the time evenly, but does not create equal third-stop exposure increments.

Or are we not talking about the same thing?

sadly your attitude doesn't make me feel too inspired to keep doing it.

I wasn't aware I had an attitube !