Advice on Zone Strips

Ian-Barber

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On a single sheet of 5x4 film, I am wanting to end up with 4 strips of different exposures ranging from zone 2 - zone 5.

Without physically cutting the film into strips, is it possible to slide the dark slide in or out to cover parts of the film during the exposure and if so how would yo do it.
 

mpirie

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Could you paint some white lines on the darkslide with Tipex at regular intervals?

What about using a Stouffer 21-step wedge to give a fuller range of exposure?

Mike
 

Ian-Barber

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Could you paint some white lines on the darkslide with Tipex at regular intervals?Mike
Would I expose the whole sheet to Zone 2, then open up 1 stop slide the slide in and expose again and keep doing this to the end
 

David M

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That would be the way. There is something called intermittency, which means that the sum of several exposures is not the same as one long one, but you don't say how accurate you need to be. Will you also need an unexposed strip to establish FB+F? There are others on the forum who can give more detailed advice.
In any case, Zones are not specific vales, but ranges of density, so that everything between ZIV and ZVI is ZV. Just hold a ruler against the slide as you push it in. If you need to be accurate in the spacing, cut measured pieces of card to size for each advance and push the slide against each one as you go. Easy to check with an empty holder.
For ultimate control, you could cut windows in a series of sheaths and make successive exposures through them, but this seems wilfully extravagant. I have heard of drilling a set of holes in one sheath, which were covered with opaque tape and exposed one at a time, but this would give spots rather than strips. It still looks like vandalism to me, but no doubt there was a good reason.
 

mpirie

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Might be easier to use the step-wedge?

At least that way you'd get a range of densities on the one sheet.

If you have your film speed sussed, then 6 steps either side of step 11 will give you Zii to Zviii
 
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Ian-Barber

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What I am trying to do is nail down just how many stops below zone 5 for a given box of film, I can get the scanner to reveal texture. I will use the film edge (clear) as a reference point for scanner noise
 

David M

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So you will be using something textured (the customary towel perhaps) as a target? Very interesting and useful.
As it will necessarily include a range of tones, please ignore my intermittency comment. Pushing in the sheath in steps should easily suffice.
It might be worthwhile to cover the opening of the dark slide while making your manipulations. A pity to have a random light leak marring the experiment. You've probably thought of this already.
 

martin-f5

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John says in his book, which I highly recommend:

"
If you are working with large-format film, using a sheet per zone can become expensive.
Exposing zones on a single sheet by building up the necessary exposures is inaccurate,
as film's response to additional exposures is not propotional. Densities will be less than those produced by a single exposure.
I have generally compromised by working out exposures for a full scale, but exposing only key zones.

John Blakemore's Blck and White Photography Workshop
Making a grey sacel, page 71
"
We may have to cut a sheet in some parts for exposing them.
 

David M

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Easy enough to use double-sided tape on slices of film in the holder, but you'd need to work out a way to process them. If they were cut 35mm wide, an ordinary spiral tank might work. Tray development would be possible but a bit fiddly with small pieces. Happily for this purpose, scratches wouldn't matter.
 

martin-f5

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35mm is a great idea, brilliant, they fit into normal developertanks so you can go on with 300ml developer.
But where to find a 18% grey or Zone V towel?
 

Ian-Barber

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35mm is a great idea, brilliant, they fit into normal developertanks so you can go on with 300ml developer.
But where to find a 18% grey or Zone V towel?
can't you just use a white towel which the meter will indicate as 18% grey and move the exposure from what the meter says
 

martin-f5

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in theory I would say yes, but I think you'll lose structure if you shot in zone VIII
 

David M

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Martin, I think the original intention was to see where detail begins to be lost, but in the context of scanning, rather than enlarging. The actual reflectance of the chosen subject isn't important. It's placement that determines negative density.
In a real situation, it's easy to imagine a white towel in shade being placed on ZV and another one in sunlight much higher.
It might be a rather odd picture... Laundry at Noon perhaps?
The sun is out. A piece of white textured cloth in direct sunlight is more than five stops brighter than in the shade under a tree. Gossen Lunasix F – the swing needle makes it easy to do this.
 

martin-f5

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John suggested this for film ISO testing and therefore it's important to know if there is texture in zone III or VII.
Comparing this to a 18% grey card there is no way to find out where your film ends.
But yes for it's all about enlarging, I don't own a scanner and so it's probably a different journey.
 
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