Determine Dynamic Range

[Tim Gray]

[font color=\'#000000\']That's exactly the technique I've heard described for digital...[/font]

[howard smith]

[font color=\'#000000\']Jack, are talking about the dark end of the scale?

I have no idea how to do this, but it seems like pre-flashing a digital camera would get the dark areas up and running so the next little bit of exposure would count.  Works great with film, but I don't know about digital.[/font]

[Spencer]

[font color=\'#000000\']I am a recent covert from the wet darkroom. I would like to find the exact dynamic range for my camera. I am guessing I would go about this the same way one would for film. Expose a evenly lit subject that has some texture, like a cement wall, and see at what point you lose detail at both the high and low ends. Then count the stops. Much like one would do when determining development time for film.

Could somenone confirm that this is the best way to determine DR?

Thanks,
Spencer[/font]

[Jack Flesher]

[font color=\'#000000\']Agreed.  The only thing I can add is that when you do the test, use 1/3-stop increments (at least beyond about +/-2 stops) because the thresholds fall off pretty rapidly when they start to go.[/font]

[Jack Flesher]

[font color=\'#000000\']Jack, are talking about the dark end of the scale?

I have no idea how to do this, but it seems like pre-flashing a digital camera would get the dark areas up and running so the next little bit of exposure would count.  Works great with film, but I don't know about digital.[/font]

[font color=\'#000000\']Actually both ends.  

And you can manufacture expanded DR in digital. For example you could take a single RAW image and "expose to the right" but without blowing the whites.  This will establish your upper values.  Convert the file as you noramally would. Next, you would convert it a second time, only this time adding the necessary exposure to bring up the shadow detail to where you want it, esentially "pushing" the initial exposure.  Now you have two identically-framed images in PS; one with good whites and another with good shadows.  Layer them and blend them  accordingly with a mask, and voilla, increased -- or more accurately, "manufactured" DR.

Cheers,
Jack[/font]