density range

I'm trying to get a density range of 1.7 with some difficulty. I use

fp4 (rated at asa 50) with d76 (1:3). 120% development over my N time

gets me around 2.3 on the high value. But shadow details (usually

placed around zone III) have also risen quite sustantially to

around .75. So I'm getting around 1.55 DR on the average.

 

For a low contrast scene (usually 2-3 stops value), if I had to do an

N+2, the increased 120% overdevelopment over N+2 resulted in the

shadow details move up almost as much as the high value (Is that

fogged?), thus a helpless low contrast negative.

 

What are my best options: Change film? Change developer/dilution?

Place the shadow at a lower level (e.g. zone I)? Increase development

further? Digital negative?

 

Many thanks for your answers.

When using N+ development to increase contrast, use a higher EI. This will keep the shadow details from moving up as much. For N+2, you should at least double the EI to 100, and maybe even higher.

What zone are you attempting to get at 1.7? That seems kind of high. I think I shot for a Zone 8 at 1.48, and even that was a little high.

 

At 1:3, I'm not surprised that you are having trouble.

D 76 is usually used either stock or 1:1. Is there some special reason you're using it at 1:3? I would have thought that using a dilution that high would tend to reduce the highlight density and thus reduce the density range, but you say the problem is on the shadow side, not the highlights, so apparently that isn't happening.

 

Apart from that, when planning for plus or minus development you need to adjust the exposure index - higher speed (i.e. less exposure) if planning N plus, lower speed (i.e. greater exposure) if planning N minus. I usually see adjustments of a half a stop recommended for plus and minus one but I've always used a full stop and it has worked well for me with HP5+ and T Max 100 though I don't usually seek a specific density range. A couple tests should establish the right number for you.

When you are planning increased development for push processing you need to decrease your exposure to compensate for the overall increase in density of the negative. I would raise the ISO or put my shadows on a lower zone like 1.5 or 2.

I agree with the suggestion that you should change your dilution for starters, and try D-76 (1:1) or stock. You may be exhausting the developer before reaching the Dmax of the film.

 

If you are processing in open trays, is the darkroom really dark? With the long development times you must be getting if you are trying for N+1 or N+2 with D-76 (1:3), small light leaks could become significant enough to increase base fog.

On the development side you might think of changing a few things. Use at least 2-3 times the developer indicated for the amount of film being developed so you don't run into developer exhaustion while processing the film. Using the minimum needed doesn't give you any leeway at all. If you soup the negatives in 3 times the developer needed you have an extra safety margin while developing & won't run into developer exhaustion problems. The suggestions of using a more concentrated developer may help also. Changing to a film that goes crazy with density might work. TMax 100 is a good one for this if you care to try it.

Try Fp4 in Pyro PMK, ABC or Pyro Rollo! Rate it at ASA 64 for starters. Adjust for your own equipment / meter / etc.

Incredible scale! - and NO blocked up highlights!

(One thing: you cannot use a B/W densitometer to read Pyro negs properly. )

 

 

Per Volquartz

 

http://www.volquartz.com/pervolquartz

After reading all the responses, I have a question: do you want to increase density RANGE (as in the delta between the lowest and highest values) or HIGHEST density (the highlightiest highlights)?

Neil, I'm attempting a high of around 2.3 (zone VIII) and a low of around .60 (zone III) to get A DR or 1.7 for salt paper.

 

Mark, Brian & James, Yes, 1:3 dilution (18 degree celcius) gets me to zone VIII at a normal development time of 9:40. I didn't feel comfortable going at 1:1 dilution or straight due to the shorter time. But I guess for the extensive development time required for a long range (1.7 DR) negative, I could go 1:1 or straight. But at my current 1:3 dilution, I could get there (2.3 on highlight). Just that the shadow (usually placed at zone III)goes up quite a bit along with it. I think your (along with the other contributors) suggestion to adjust the index for plus/minus is the way to go.

 

David & Dan Smith, my understanding is that 125ml stock is minimum requirement for 5x7 film (250ml for 8x10). So 125ml stock to make up 500ml working solution (effectively 1:3 dilution) shouldn't cause exhaustion, right? Am I missing something here? Wouldn't a more active dilution (adding 2-3 times the developer indicated for the amount of film) create more activity in the shadow details and as a result pushes up the low value further?

 

Per, Pyro isn't an option for me. Pretty strict rules here. Read much good things about Pyro. Wish I could use it.

 

Chad, yes I need to increase the density range (DR). Around 1.7 for salt.

T-max100 in T-max developer will get you a LOT more density, and on the straight line of the film curve as well.<p>D-76 has a solvent and physical development action, which means that high density build up is curtailed with most films.

Aaron wrote:

"David & Dan Smith, my understanding is that 125ml stock is minimum requirement for 5x7 film (250ml for 8x10). So 125ml stock to make up 500ml working solution (effectively 1:3 dilution) shouldn't cause exhaustion, right? Am I missing something here?"

 

You are missing what I am trying to say. Instead of using the minimum amount of the developer for a given surface area of film, use more than the minimum required though you use the same dilution. If 125ml is the minimum stated, use 250ml to 375 of the stock & dilute as normal. This provides extra developer to cover longer developing times, oxidation and the 'fudge factor' you don't have when working with negatives that have a lot of silver to be reduced. Minimum amounts are just that and don't always give optimum results. The extra developer will save you a few images as it will give full development for the full time with its extra stock in reserve.

Thanks Dan. Got it now! Thanks to all.

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