Most reciprocity failure?

[rco3]

I have a need for some film in 120 and possibly in 35mm with appalling reciprocity failure in the 1-5 s range. Well, 4x5 could work, too. I often hear about how good certain films are for lack of reciprocity failure, but much less talk about which are worst. In my case, it's a desirable characteristic. Thoughts, anyone?

--Rob

 

[Nicholas Lindan]

Arista EDU 100 / Fomapan 100 is really wretched... 2x failure at 1 second, 8x failure at 10 seconds, 16x at 100 seconds

http://www.foma.cz/upload/foma/prilohy/f_pan_100_en.pdf

Reciprocity failure isn't really a time failure but a failure of sensitivity at low film illumination levels. Time is used because it corresponds to illumination at the film plane for a Zone V tone.

However, few of us take pictures of 18% gray cards.

For the above Fomapan, with a reference illumination level such that Zone V / 18% gray meters for a 1/2 second exposure, Zone IV will be 1 stop underexposed and Zone II will be 3 stops underexposed. If Zone V meters for a 1 second exposure, and you double the exposure to two seconds to compensate, then Zone VI-IX will be one stop overexposed and Zone II will be two stops under exposed. And so on and so forth.

 

[Vaughn]

Efke...

 

[rco3]

Thanks, fellas. I have some Fomapan 100 in 4x5 right now. I'll have to give it a try on this project.

 

[pgomena]

It's not in current production, but a friend of mine joked that Bergger 200 started exhibiting reciprocity failure at 1/125 of a second. I think Bergger was a Fortepan variant.

Peter Gomena

 

[Ian Grant]

I did some practical reciprocity tests with Fomapan 200 and it was nowhere remotely near as bad as the published figures.

The problem is there are far too many variables but in low daylight light levels 1 second at f8 it needed around half a stop extra and at 10 seconds at f8 only a stop extra not the 3 recommended by Foma. I've also used Fomapan 100 LF film in very low light levels and again little reciprocity failure.

Most manufacturers only give ball park reciprocity figures because the reality is you need to test for all conditions, bracketing and notes can be enough.

Ian

 

[Ian Grant]

It's not in current production, but a friend of mine joked that Bergger 200 started exhibiting reciprocity failure at 1/125 of a second. I think Bergger was a Fortepan variant.

Peter Gomena

Berrger 200 was Fortepan 200 which is itself a variant/descendent of Kodak Super-XX which the Forte factory manufactured along with Tri-X just before WWII when it was Kodak Ltd's Hungarian coating plant. The European Kodak plants came under the auspices of Kodak Ltd in the UK rather than Eastman Kodak in Rochester, US.

Contrary to a digital company who've just launched a Tri-X plugin for Photoshop (to emulate the feel of the film digitally) on what they said was Tri-X's 50th Anniversary it was actually introduced in 1938/9 over 20 years earlier along with Plus-X, and Super-XX.

I've still got 2 boxes of Fortepan 200 in 10x8 from the very last coating run and I can't say I've noticed any reciprocity but then I'd guess I've not used it a shutter speeds faster than an 1/8th second

Ian

 

[Mainecoonmaniac]

So far Fuji Neopan Acros has the best reciprocity response from my experience. Check out Flickr for images.

 

[ntenny]

Reciprocity failure isn't really a time failure but a failure of sensitivity at low film illumination levels. Time is used because it corresponds to illumination at the film plane for a Zone V tone.

Thank you for the explanation---I've always wondered about that, why time rather than "number of photons" was the metric.

I agree about Fomapan 100---it shoots like they forgot to put the reciprocity in when they mixed the emulsion! I find it useful for really long nighttime exposures, where the reciprocity failure helps control the highlights.

-NT

 

[Ian Grant]

Reciprocity affects the shadows more than the highlights. So it isn't going to help control the highlights.

Ian

 

[bobwysiwyg]

Came upon this at one time and felt it was a pretty good description.

http://home.earthlink.net/~kitathome/LunarLight/moonlight_gallery/technique/reciprocity.htm