You brought up an important point. You have overexposed to fight contrast. Well, if you overexpose and either under develop to get lower contrast or develop normally, you will be talking about at least 2 stops which is about ISO 6 or thereabouts. This will reduce the contrast nicely, but it will not center a tonal scale at normal development.
All of my photos include the MacBeth Checker and have the neutral scale centered with Dmin on one side and Dmax on the other, and they were given normal development, no under or over, and no flash.
I think that all of this is important. I am trying to get at the full tonal range. To actually do this with a paper, I suggest a grade 0 or grade 1 graded paper.
As for spectral sensitivity, the Ilford MGIV and most graded papers today have a short green sensitizer that is much shorter than I expected. It peaks at about 520 nm as opposed to 560 - 580 for a "normal" green sensitizer. This gives things much more than blue or dark green no detail or image at all and seems to further increase contrast demanding more overexposure to the eye.
Take a look at my images above and see what I mean about centering the density values on the scale.
Just shot my Gretag chart under strobes. Processed normally for print paper, Sprint 1:9 for 3 minutes. Looks pretty good. I don't know what would account for the discrepancies...perhaps PE is using a different developer and/or method that would account for his ISO being so radically higher than mine and what others have experienced. Very weird. I'll get it out of the wash soon...
See my previous posts Michael which include the entire process and exposure methodology. If I used 3 minutes in Dektol or Liquidol, I think that the negatives would be seriously overdeveloped and dark.
Dektol 1:3 for 60 seconds is your normal development time? This is where you are arriving at your ISO of 25?
Dektol 1:2 for 2 minutes seems like normal print paper development time for me in my own darkroom work. The Sprint paper developer I am using is nearly identical to Dektol.
Maybe that's where the difference is coming in. I'm going to scan these negatives right now...
If you consider for a minute that what you suggest would darken my paper negatives a bit, that would then mean that they are even faster than ISO 25 at my current exposure.
Originally Posted by Michael Slade
What do you think about that?
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I'm not sure. I think I'm kind of confused now. I wasn't trying to suggest anything, just trying to figure out what you have been doing.
Here's my shot from today.
Several things might be happening:
1. I might have the ISO incorrectly set for the paper.
2. I might be processing incorrectly.
3. I might be scanning incorrectly.
4. I might be printing incorrectly.
Those things might all be happening, one at a time, in multiple combinations, or all at once. I am willing to concede that. But...one thing I do know is that I like my negatives and I like the prints I'm able to get from them.
Last edited by Michael Slade; 01-12-2009 at 05:07 PM. Click to view previous post history.
Reason: image didn't load
I would like to see the negative scan.
Your positive scan is considerably lower in contrast than mine, and quite a bit lighter. IDK what that means offhand at this point, but the 3rd patch from the left in the second row of your print is the red patch and should be as black as Dmax taken with this ortho paper, and the right hand bottom patch in the above should be black as well.
The left bottom patch should equal Dmin.
Somehow, the positive appears muted to me.
I looked at my originals here and they look close to the scan of the negative. A print is close to my positive scan as well.
I would like to add that my process conditions yield good prints with the proper tonality when used with an enlarger exposure of f11 - f16 at 12" for an 8x10 print. I use a 30M filter as per the enlarger instructions for grade 2 and this gives me a gamma of about 2.5 on a Stouffer wedge.
I would like to add that the negative step scale should show a distinct step in every position in that bottom row, from Dmin to Dmax if you have exposed it properly and developed it properly.
I would also add that there is nothing wrong with messing with the exposure and process in order to make a good picture, but this is not the way to start measuring the capability of the paper. You start by getting Dmin and Dmax centered with a process that can give good prints by normal means.
Last edited by Photo Engineer; 01-12-2009 at 06:27 PM. Click to view previous post history.
Reason: Additions and spelling....
I scanned the negative then inverted it in Photoshop. I also gave it a bit of a tweak in levels and a minor curve. I was surprized honestly to find that yours and mine were as close as they were.
Originally Posted by Photo Engineer
I am at home now, so I can't really re-do the scan, but I will and then send the original untweaked version.
I think that there could be a whole lot to be learned about using paper negatives. I was considering using them for alt-processes later on...
I'll see what I can't get done tomorrow. I have a bunch of shooting to do, ironically on paper negative, but I'll try to make time to get you a good unmolested scan.
even though we seem to be all shooting paper at different iso's
we are getting negatives we are able to print.
i like printing paper negatives that are a little thin,
so the positive looks good ..
maybe that is the difference.
i over expose and develop like i do, so i can get negatives i will print / contact print, not just scan ..
are you contact printing your paper negatives?
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I scan all of them and post them here either as negatives or inverted as positives, or both as I did in the earlier posts. I suspect that some of these very excellent paper negatives were shot on the shoulder (slower) portion of the curve and then underdeveloped to lower contrast to get good contrast from high contrast papers. The alternative would be to shoot on the toe and overdevelop to get good negatives.
I have done both. In the case in point, I have avoided either, but I could shoot on the toe and probably force things to an ISO 50 or maybe even 100. IDK. I was not trying to do that.
You can push and pull papers the same way as film and without knowing the ISO, you can do this just to get the picture you want.
BTW, I "know" that the ISO speed of the Endura Yellow layer emulsion is nearly 100 and that the Cyan layer is about 25. When you add in the filter pack and orange mask, the overall speed to a neutral reduces speed to about ISO 25. I did that experiment at EK as well. You might want to see Bujor B's work on Photo Net where he exposed CA and Endura papers in camera with a Tungsten filter pack and got some good positive color prints by cross processing.