Precision Digital Negatives

[sanking]

Sandy, thanks a bunch for sorting some of this out for me, I really appreciate it. Now if you could also send me some of your talent.......

Jeremy,

Thanks for the nice comment, but the truth is that I just have a bit more experience with the PDN method. I have been testing different versions of Mark's method for a couple of years and some of it had to stick. Once you have made four or five tests and confirmed the results with real prints you will feel as confident as I do at this.

Sandy

[smieglitz]

I don't have a copy of the book on hand and don't recall that section about how to ZERO the densitometer. My intuition would be to just ZERO (calibrate) the densitometer as per instructions in the manual so I think there may be some kind of misunderstanding here.about the task. What I believe Mark means is that you should not chose one of the squares on the tonal palette that is pure paper white as the basis for the colorization because this will result in bald highlights on the print. And we never want pure paper white anywhere on a print. Instead, chose a square that has some density and is at least one or two removed from the one that is pure paper white. Remember, the square you chooses determines the density range of your negatives. If you choose one that is absolutley white the resulting negatives will have too much contrast.

As to how you should read, just be consistent and always read the print with the same orientation. And I would chose the orientation that gives maximum Dmax. Folks who have color reflection densitometers will find that a process like Pt./Pd. will have different Dmax values depending on whether the reading is in Visual, Red, Green or Blue. In this case I would use Visual even though Blue will usually give the higher Dmax because Visual is the more common reference when comparing results.

Sandy

Sandy,

Reading this it appears that one needs a reflection densitometer to calibrate using Mark's method. Is this correct? I seem to recall someone saying in another thread that a flatbed scanner could be used for that purpose. Am I dreaming?

As you are aware from the alt process list, I have been trying to make a good digital negative for Van Dyke Brownprinting. My other interests for digital negs are for albumen and salted paper. Given the extreme density ranges needed for these 3 processes, will Mark's book have any utility ? I'm really not interested in Pt/Pd for reasons I don't understand nor do cyanotypes float my boat. Am I mistaken in assuming Mark's book is primarily geared to negatives for Pt/pd and silverprinting?

Thanks for any info and opinions,

Joe

[sanking]

Sandy,

Reading this it appears that one needs a reflection densitometer to calibrate using Mark's method. Is this correct? I seem to recall someone saying in another thread that a flatbed scanner could be used for that purpose. Am I dreaming?

As you are aware from the alt process list, I have been trying to make a good digital negative for Van Dyke Brownprinting. My other interests for digital negs are for albumen and salted paper. Given the extreme density ranges needed for these 3 processes, will Mark's book have any utility ? I'm really not interested in Pt/Pd for reasons I don't understand nor do cyanotypes float my boat. Am I mistaken in assuming Mark's book is primarily geared to negatives for Pt/pd and silverprinting?

Thanks for any info and opinions,

Joe

Joe,

Mark's book Precision Digital Negatives has directions for using a scanner to measure densities but I don't know how to do it as I use a densitometer.

It is not correct to say that Mark's book is primarily geared to negatives for Pt./Pd and silver. It can be used for any type of printing, incluidng VDB, salted paper and albumen. However, the colorized method he describes which allows one to match the density of the digital negative to the exposure scale of the process will not work with VDB, salted paper and albumen with the Epson 2200 because the pigmented ink set of this printer does not give enough contrast with the color options of the palette. With this printer you must print in neutral or black inks, or some combination of black and colored inks, to get the necessary contrast. You can, however, get enough contrast with colorized negatives for VDB, albumen and salted paper with a number of other Epson printes, including the 1280 dye based printer and the printers that use DuraBrite pigmented ink sets.


Sandy

[Jeremy]

I would say that it is geared towards any process where a contact print can be/is used, but someone more knowledgeable will probably speak up.

You do NOT have to have a densitometer for any part of this system as long as you have a flatbed scanner--it's what I used and my prints look great to me!

[donbga]

I would say that it is geared towards any process where a contact print can be/is used, but someone more knowledgeable will probably speak up.

You do NOT have to have a densitometer for any part of this system as long as you have a flatbed scanner--it's what I used and my prints look great to me!

FWIW,

If you can use Vuescan with your scanner it can give log values of step tablets or any thing else, However I don't think it will give accurate results with log densities greater than 2.1 to 2.3. Seems like I measured a calibrated Stouffer's step wedge a while back with my Epson 2450 and that was the limit. This is probably more of a limitation of the scanner than the software.

Don Bryant

[donbga]

Sandy,

As you are aware from the alt process list, I have been trying to make a good digital negative for Van Dyke Brownprinting.
Joe

One thing that occured to me after reading Sandy's reply is that for VDBs you can use a lower contrast sensitiser mix by adding Ferric Citrate.

FC will increase print exposure times but it is an effective option if you don't have a dye based printer.

Don Bryant

[sanking]

One thing that occured to me after reading Sandy's reply is that for VDBs you can use a lower contrast sensitiser mix by adding Ferric Citrate.

FC will increase print exposure times but it is an effective option if you don't have a dye based printer.

Don Bryant

The mixture in various proportions of Classic VDB sensitizer (ferric ammonium citrate) with Ferric Citrate is indeed very effective at controlling contrast in VDB. In fact, it is the only way I know that one can control contrast with VDB. The methods described in some of the literature, i.e. adding dichromate to the sensitizer and/or adding it to the developing water, do not work. However, the addition of ferric citrate results in a rather significant shift in color of VDB away from chocolate brown toward rust brown which some may not find attractive.

Given the fact that one can get plenty of contrast out of the neutral black inks of the Epson 2200 I am of the opinion that the best method for working with this printer with processes such as albumen, salted paper and VDB would be to blend in some black with the colors of the color palette. In another thread a few weeks ago David Harris suggested a method for blending in some black with the other colors to boost contrast. What he suggested was this.

1. Set up a new layer above the green color fill layer.
2. Fill the new layer with black.
3. Set blend mode for new layer to multiply.
4. Choose blending options for the new layer and move the white sliders on the Blend if underlying layer scale, pressing the Alt key to separate the two white sliders. Move the sliders until about the darkest 20 squares or so on the tonal palette are visibly darkened - I found this to be 50/175. I chose 20 squares so that the blend in would be very gradual.
5. Reduce the opacity of the new layer. You will need to do some tests with your alt process to determine the correct opacity. I found 2% to be right for palladium toned POP - when printed it produces tone in the 100 square, but 101 is pure white (I prefer to have a pure white, others might prefer to have some tone).

I have not tried this myself but the methodology appears to be sound.


Sandy

[smieglitz]

Thanks everyone for the information. I'll check into the Vuescan software and give the blended ink method a go.

Joe