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# Thread: BTZS 0,5 ZS 0,57 Why?

1. Originally Posted by Bill Burk
Well you could do what I do. Pick a flare value that you believe applies to your system. I say 0.4 Log Exposure Units.

At an appropriate part of the curve (and this is where I just throw darts and start where the curve crosses 0.1 density on the non-flare test plots), identify the exposure. Now identify the exposure at 0.4 Log Exposure Units to the right.

Take the difference*. Add that amount (call it flare exposure) to the exposure for each plotted point. Look at the original graph to see what density you get for the summed exposure (original plus flare exposure*). Plot that density point directly above the original plotted point.

As you move to the right, the flare exposure becomes logarithmically less significant, so the new curve will taper.

Sounds awful, maybe someone can explain it better than me.

*Get the antilogs so you are summing arithmetic values and then get the log of that sum
I think I get this explanation.
Now for the lazy and wanting to get quick results (getting deeply involved needs to come later since I want to carry on Photographing, and learning by doing) if I continue plotting my curves and using the WBM method everything should be fine again.
I am going to replot my data concidering flare to see what I get.
I used to plot on paper now I use computer spreadsheets since it is clean in the optic.
I also have the BTZS plotter programm, this is what got me confused, I added flair in the programm which resulted in really weird curves and nothing seemed right. I changed the paper ES from 1,05 to 1,20 which as I understand is the ZS way and I seem to get "normal" results.

2. i wondere about that for years, and after asking phil about it, i had to disagree with his arithmatic. to me, the average gradient is the SBR/ NDR, which is 1.2@ grade 2. consequently, a 'normal gradient is7*0.3/1.05 or 1.2/2.1=0.57. i know fred newman thinks this is too contrasty, but i can't see a flaw in my logic.(see the attached for details)

3. Originally Posted by RalphLambrecht
i wondere about that for years, and after asking phil about it, i had to disagree with his arithmatic. to me, the average gradient is the SBR/ NDR, which is 1.2@ grade 2. consequently, a 'normal gradient is7*0.3/1.05 or 1.2/2.1=0.57. i know fred newman thinks this is too contrasty, but i can't see a flaw in my logic.(see the attached for details)
Ralph, you know where I stand on this issue.

4. i do, and i don't have the strength for another detailed conversation. there is too much flare around here, but do you know fred newman came to his conclusion0.57 being too contrasty?

5. Yes Ralph I had a short Email exchange with him wondering about this and he said that 0,57 is too contrasty. It was short and blunt!

6. Originally Posted by RalphLambrecht
i do, and i don't have the strength for another detailed conversation. there is too much flare around here, but do you know fred newman came to his conclusion0.57 being too contrasty?
I would love to read this discussion, where can I find it??

7. Originally Posted by RalphLambrecht
i do, and i don't have the strength for another detailed conversation. there is too much flare around here, but do you know fred newman came to his conclusion0.57 being too contrasty?
Well, I've found that understanding flare answers many of the outstanding questions in photography. Flare is the answer to Andreas' gradient question.

As for 0.57 being too contrasty, I'm always interested in a well reasoned argument, but I really can't see how there can be one with this.

8. Originally Posted by RalphLambrecht
fred newman came to his conclusion0.57 being too contrasty?
It's probably a misinterpretation of flare.

9. he must be ounder estimating flarethen.

10. Originally Posted by RalphLambrecht
he must be ounder estimating flarethen.
That's my first thought. Another possibility is a change in the LER or gradient parameters, or a different value for the average luminance range.

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