Reciprocity lightmeter ?

[mfogiel]

I'm recently looking into longer exposures, pinholes, etc, and when I was out late with my camera, my Iphone proved to be really priceless: I could illuminate my Rolleiflex to set the speed and exposure in the dark, I could measure the light and I could work out my reciprocity correction, but I had to constantly fiddle switching between apps.
And a spontaneous and obvious thought has sprung up: why not combine the Reciprocity Timer with the lightmeter, possibly augmented by the incident light sensor and high sensitivity ( that part has been done already by Lumi, I think) ?
You could indicate the film, exposure correction, f stop and voila' you'd get a reciprocity adjusted time for f stops as high as 500...
What do you think of this?

 

[sevo]

That is an idea that should really be suggested to the authors of the various light meter apps. The biggest problem would be to define reciprocity in a way that is easy to feed into the app - it would take hours with grid paper to translate the non-numerical curve drawings usually published by film manufacturers. Might a definition that merely gives the starting point and angle be good enough?

 

[mfogiel]

There is already the Reciprocity Timer app which is quite well made, but it ain't a lightmeter.

 

[sevo]

There is already the Reciprocity Timer app which is quite well made, but it ain't a lightmeter.

It being on the Dark Side, unable to run on my Android devices, how does it work?

 

[mfogiel]

You set the film type, the readout of your lightmeter's exposure time, possible exposure adjustment compensation ( in half stops), you can also dial in f length of the lens and bellows extension as well as a filter with it's factor, and the program reads out the modified time with a handy reading that becomes a count down timer which you can even trigger by voice... Quite smart app, I believe the author was consulting here before he made it.

 

[sevo]

How does it deal with different reciprocity characteristics? There is a whole world of a difference between Neopan 100 and the last remains of EPP in my fridge...

 

[Sarcophilus Harrisii]

Or you could use Fuji. As I recall, both Acros 100 and Provia 100F have a 128 second exposure window before adjustments for reciprocity are a consideration. It's one of the few issues I have with the various Ilford black and white films. None of them are much good for unadjusted exposures over a second or two.

 

[mfogiel]

There is a database of different film stocks inside the app.