Reciprocity failure with FAST shutter speeds.

[jip]

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I am wondering how Reciprocity failure works with very fast shutter speeds like the R8 with a 1/8000 shutter speed.

 

Most film is rated accurate from 1/1000 to 1 second.

 

How does this work with shutter speeds faster than 1/1000?

 

Might using a ND filter be better than to use the very high speeds?

 

Thanks!!

[fotohuis]

Correct but the deviation is above 1/2000s and till 1/8000s it is not much. So I would bother more on the other end: > 1-2s.

Or use the Fuji Acros 100 with a linear exposure till 120 seconds. With this modern film I would not do any reciproke correction between 1/8000s-120s.

[jip]

Thanks for the quick response, film is still sort if new for me. I've developed black and white myself but I'm still learning. Like recently I read about the reciprocity failure. Then I though yes of course (remembering my chemistry class) but wasn't sure how it would deviate.

 

Films I most use are TRI-X and Portra by Kodak. Would it be save to use the 1/8000 shutters speed with those films? Or anything shorter than 1/1000 at all?

[erl]

I often use 1/8000 on my R8. Mainly because I use a large aperture lens even during good light. Exposure has never been a problem because of the fast shutter speed. Use it with impunity.

 

P.S. I use a whole range of films. No difference that I can detect.

[StS]

(...)

Films I most use are TRI-X and Portra by Kodak. Would it be save to use the 1/8000 shutters speed with those films? Or anything shorter than 1/1000 at all?

 

Both films are very tolerant in my experience, especially Tri-X. If you look in the data sheet for Tri-X, the correction is half a stop (plus 15% development increase) for 1/10000 s but Kodak also mention, that Tri-X can be underexposed by one stop without correction. If you skip the increase of development time, you might even make life more easy for your film scanner.

 

I wonder, how accurate the camera shutter actually is at 1/8000.

 

If really in doubt, especially with slide film, you can run a test series with different aperture/shutter time combinations on the same strip - I doubt there will be a visible difference.

 

Stefan

[jip]

Okay so basically just use it, and if I understand right the reciprocity failure is usually only noticed with long shutter speeds at night?

[CrisRose]

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That was actually a really interesting question - i knew about the problem at very low speeds, but i didn't even think about very high ones. Clearly i'm getting too used to shooting 1/4000 and 1/8000 on digital

[jip]

I just read that most modern films say their accuracy is good between 1/10000 an 1 second so I can easily use the 1/8000 shutter. On the R8/9

[TomB_tx]

Automatic strobe flash units can quench the light burst to 1/50,000 or less, so you might search for effects of reciprocity with strobe use.