Zone System with the Help of Photoshop, I thought I had a system...
note: I was not sure if this forum is the right place for this question but I didnt know where else to post.
Expecting to emulate the Zone System Steps using the help of Photoshop, I created a stepwedge of 11 Zones in aRGB space. The steps used were:
0 - I - II III IV V - VI VII VIII - IX - X
0 33 51 72 94 126 143 169 197 224 255
Having printed this on Matte finish Cold Press Natural Epson professional paper using an Epson R2880 Pro printer from Photoshop Managing color and the right paper profile from Epson, I went outside under very even ilumination overcast sky, I spot mettered each of the steps with a Sekonik Light meter in reflective mode. To my dissapointment, the steps do not equal into a one stop difference between one step and the other. For some steps the difference was 1/2 stop or less, particularly towards highlights area. Also there seem to be a big jump in tones from Zone 9 to Zone 10 in retrospect to traditional darkroom. I don't think there is enough room in between steps to vary the tones in such a way that would accomodate the 1 stop difference.
My idea was to shoot this with Film to study expansion and contraction all in one frame. In other words, I would shoot several frames of the same card, then develop them first Normal, then +15% time, +30% etc with the idea of arriving to my N+1, N+2 , N-1, N-2 times. I came up with this, first because I dont have a densitomer, neither do I want a super exact science, and I thought it would be good to be able to do this all in one frame.
Thank you for any ideas regarding the steps in the wedge and zone system, or on why this will not work ?
if everyone agrees that this will not work, what is a practical way to arrive at my N+1 N+2, etc times, without a densitometer.
Here's a link to a place you can get a proper step wedge http://www.stouffer.net/TransPage.htm
How to do things in PS is off topic here on APUG.
Mark Barendt, Ignacio, CO
"We do not see things the way they are. We see things the way we are." Anaïs Nin
Make a smoother grayscale all the way from 0 to 255 and label the grays so you can find them.
Then take spotmeter readings and LOOK for where the spotmeter says they are one-stop-apart.
Those will be your printout steps. That's fine. Print a new target with the full stop steps you found. You might only really get 4 or 5 full stops of meter reading differences from White to Black. Probably best you can do with a reflective target.
I think that's the mental block you are running up against right now. The rest will come easy.
markbarendt is right. Look how "cheap" these transparent step wedges are. They last a lifetime. I've found no other cheap photo accessory as useful as a step wedge - considering how much cost of material and trouble it is to makeshift without one...
Originally Posted by markbarendt
But if the idea is a journey to understanding, then any path that gets you there is fine. Just like climbing straight up a rock gets you to the top, same as taking a walk up the backside.
Considering OP wants to make a test pattern for traditional testing, I think it's OK to talk.
that's right. your paper does not provide large enough of a SBR to do what you want. the whites are not bright enough and the darks are not dark enough. also , a a digital zone scale is not linear. you need to work out a transfer function for your paper(not a simple task)i'd post my atempt, but APUG does not allow me to post filesthat large.
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Bill, thank you. You are right, I am trying to climb a rock possibly the sharpest edge... but I learned a few things from your answers. I guess what I was trying to do is jam up all the zones into one frame. My original idea has to do with trying to determine my n+1, n+2, n-1 etc times by jamming all the 11 zones into one frame and develop separetely (kind of more efficient). I dont have a densitometer or cannot spend too much film, paper, chemicals. thats why I came up with this idea. I figured if I would be able to jam all the zones into one frame, I would only have to shoot a few ones and I could reuse the chemicals since I am only developing one frame.
Any ideas , if I buy a transmission stepwedge, how do I shoot that ? by transmitted light ? by the way I am using 35mm film.
You could go ahead with your plan to create a printout with about 5 stops difference from dark gray to light gray, and then shoot two shots of this "short" grayscale at different f/stops to cover appropriate exposure sets. (Like Meter and Expose for the darkest gray to be Zone V, then you can get Zone VI, VII, VIII and IX... Meter and Expose lightest gray to be Zone V and get backwards Zone IV, III, II and I).
Originally Posted by lhalcong
With a transmission stepwedge, there is a 4x5 sheet that you can tape to glass and light up from behind. Or you can get the 1/2 inch strip and lay it in contact with a strip of film pulled out in the darkroom under your enlarger for about a 1 second exposure.
Is there a formula to calculate the resulting print density? Is the 126 is about 0.75 density?
Originally Posted by lhalcong
Technical considerations like this are easily done with photoshop, but aesthetic ones are not.
“The contemplation of things as they are, without error or confusion, without substitution or imposture, is in itself a nobler thing than a whole harvest of invention”
I'm suggesting nothing more complicated than printing out a few patches of gray that the spotmeter says are one zone apart. This for the purpose of creating a camera test. You could do same selecting patches of construction paper. Technically speaking, the values that correspond to the patches you create are part of a "transfer function" but I don't say take it that far. Just go far enough to create something you can shoot.
I have a two-tone target painted on plywood ... one zone apart to the spotmeter. This goes with Minor White's teaching.