Film Characteristic Curve

markbarendt · Feb 14, 2014

BetterSense said:
I would love to be able to view complete H&D curves for various films to compare Dmax, latitude and shoulder behavior, but the way the manufactures only print the bottom 6-10 stops, it's impossible. There are plenty of reasons to be interested in the shoulder behavior including to make predictions about highlight rendition, exposure latitude, suitability of the film for masking or lithographic use, suitability for UV contact printing, or basically most of the things you need the curve for in the first place.

That is definitely a reasonable hope.

The other thing that would be nice is a comparison of developers for a given film. In those respects Kodak definitely gives us more to work with.

Photo Engineer · Feb 14, 2014

When you dodge and burn, or use split grade printing, you can use that "extra" part of the curve if it is there (by means of good exposure and good development). And, if you make a transparency from the negative, you always get the full curve as long as you have the above, and a good print film.

The long curve is also there for over and under exposure.

PE

Gerald C Koch · Feb 14, 2014

jsimoespedro said:
I understand the characteristic curve to be S-Shaped. My question is: Why do manufacturers do sometimes post the entire curve and others only the upwards section?

What you say is not completely true.

"There are more things in heaven and earth, Horatio,
Than are dreamt of in your philosophy."

The complete curve eventually flattens out and then moves downward in a negative direction. In this region density decreases with additional exposure. So things are more complicated than would be interpreted from the portion of the curve usually published. A short answer is that only the portion of the curve that is useful to most people is given.

Photo Engineer · Feb 14, 2014

Jerry, I didn't get into that (re-reversal and reversal and etc) as I thought we would start to hear too many exploding heads!

PE

Gerald C Koch · Feb 14, 2014

Photo Engineer said:
Jerry, I didn't get into that (re-reversal and reversal and etc) as I thought we would start to hear too many exploding heads!

PE

But I just had to use the quote. It just fitted so perfectly. Its not often that one can quote Shakespeare on APUG.

Photo Engineer · Feb 14, 2014

Yeah, yeah, yeah, but the poster's name was not Horatio!

BTW, if you are making direct reversal emulsions, the total curve shape gets really weird. It looks kinda like the cross section of a half pipe! There, I brought in an Olympics connection.

PE

RalphLambrecht · Feb 16, 2014

a ZoneV midtone has a typical transmission density of around 0.75.see the attached table

Film Characteristic Curve

markbarendt

Photo Engineer

Gerald C Koch

Photo Engineer

Gerald C Koch

Photo Engineer

RalphLambrecht

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