Portra 160 and 400 Reciprocity Failure

Thanks a lot for this app! Testing it now.

The only photo app I use, and it's a damn useful one in all kinds of situations.
Highly recommended, worth the price.

I would use aperture. Using shutter speed only puts one further down the curve.

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Originally Posted by jbenedict

For the purposes of exposure, "a stop is a stop" whether adjusted via aperture or shutter.

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Quote:

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Originally Posted by neil poulsen

I would use aperture. Using shutter speed only puts one further down the curve.

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Unless you're using aperture for a very specific depth of field (for esthetic reasons), which is why I always bracket via shutter speed.

Well, I'm not too much of an app person, I prefer a little chart to have in my pocket. Here's one in 1/3 stops based on time as I prefer to shoot with very small apertures. Much better than my previous one :-)

Attachment 151961

Hope this can help :-)

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Originally Posted by BM PHOTOS

Well, I'm not too much of an app person, I prefer a little chart to have in my pocket. Here's one in 1/3 stops based on time as I prefer to shoot with very small apertures. Much better than my previous one :-)

Attachment 151961

Hope this can help :-)

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Sorry BM, I don't understand your chart. What do you mean by 1/3 stops? Is it in 1/3 of a minute? I don't normally have my light meter output in stops. Didn't even know that was a thing.

Quote:

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Originally Posted by BM PHOTOS

Well, I'm not too much of an app person, I prefer a little chart to have in my pocket. Here's one in 1/3 stops based on time as I prefer to shoot with very small apertures. Much better than my previous one :-)

Attachment 151961

Hope this can help :-)

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Sorry, don't understand this.

Guys I guess you all love complications, formulas and such. Why not make it the simplest way there? 1 sec -> x stops, 2 sec -> y..

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Originally Posted by BM PHOTOS

Thanks a lot Raul! This helps tremendously

Here are a graph and a Table I made using your formula and rounding the numbers.
Hope it's useful for people in the field.

Best,

Nico

Attachment 151827

Attachment 151826

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Thank you for making this! I'm coming in 3 years later haha with what I just want to clarify. "Tm" stands for the time measured by whatever device you're using to meter the scene and "Ts" stands for what your actual shutter speed should be? So for example in your chart, it says "Tm 1" and then next to it it says "Ts 2"; that means if the light meter is telling me I should expose the scene for 1 second, I should apply your chart and expose it for 2 seconds?

Thanks again!

I love the app. Use it for it for Portra, etc. Just used it this weekend for a sunrise/sunset session. I also use it for bw film. I like the timer and being able to account for bellows extension and stops compensation (like using a red25A filter, etc)

It will be interesting to see how long an exposure you can make with Portra before there is a color shift if any. And the app says Portra 100/400, should say 160/400 I believe.