comparisation between curves

[marko_trebusak]

OK, now tet's talk .

Sandy, I understand that curves and colour are printer and process specific. Both curves we are talking about (Dan's and Clay's, see this thread) are for the same printer: Epson 2200/2100. The only variable is colour of Clay's negative. I chose density range 1.9 for Zia. I hope that I made it all right, because I don't own densitometer. When I prepared negative it was obvious that separation in highlights isn't ideal. But since I'm inexperienced and don't know how this digital negatives respond to UV light, I went out and print it. And results were as I predicted: no separation in extreme highlights. SO I'll try Dan's procedure next, and will make adjustments after I have results.

Marko

[sanking]

Marko,

For Clay's system, the key is to change the color to a lower contrast match. You could also adjust the highlight region of the curve, but changing the color is the most effective.

The key here is that different color give varying amount of contrast on negative.

What color did you use?

Sandy

OK, now tet's talk .

Sandy, I understand that curves and colour are printer and process specific. Both curves we are talking about (Dan's and Clay's, see this thread) are for the same printer: Epson 2200/2100. The only variable is colour of Clay's negative. I chose density range 1.9 for Zia. I hope that I made it all right, because I don't own densitometer. When I prepared negative it was obvious that separation in highlights isn't ideal. But since I'm inexperienced and don't know how this digital negatives respond to UV light, I went out and print it. And results were as I predicted: no separation in extreme highlights. SO I'll try Dan's procedure next, and will make adjustments after I have results.

Marko

[marko_trebusak]

Sandy, I used R:70, G:140, B:0 (for dynamic range od 1.9). Result was as I predict (beginners luck): last 4-5 squares on step tablet are white. I'm thinking about using R:127, G:255, B:0 (for dynamic range of 1.6), or something in between for next try. I'll also try to tweak curve to increase separation in midtones. Do you have any more suggestions?

Thank you
Marko

[sanking]

With the Epson 2200 try something like R=0, G=255, B=20. Or even just G=255 and no R or B. That works for me with pure palladium printing.

Sandy

Sandy, I used R:70, G:140, B:0 (for dynamic range od 1.9). Result was as I predict (beginners luck): last 4-5 squares on step tablet are white. I'm thinking about using R:127, G:255, B:0 (for dynamic range of 1.6), or something in between for next try. I'll also try to tweak curve to increase separation in midtones. Do you have any more suggestions?

Thank you
Marko

[marko_trebusak]

Thank you Sandy. I have a print by my side. Midtone separation is actually quite good (from square 5 (245) till square 80 (53)) but far away from ideal. Above that it's white paper, and belove that it's blackness. And when I compare print to image of file prepared for adjustments, it's lifeless in one word. I used following formula: 8 Ferric Lithium oxalate, 2 Ferric ammonium oxalate, 7 Lithium palladium chloride, 3 potassium chloroplatinite, 1 Tween 20. After drying, I humidifie paper above oversaturated solution of NaCl (RH~70%). I went with Ferric Lithium oxalate for slightly warm tone and add potassium chloroplatinite to increase shadow separation. I got tone that I was looking for (probably more due to humidity), but in a field of tone separation I need to do something in a field of negative preparation.

Marko

[nze]

Hello Marko

I use a color closed to the Keith Schreiber one. SO I play less with the color as did Sandy. But my personal feeling is that t is better to have a more contrasty sensitizer and to try working with smaller Drange digital negative. I find that that most problem come with high density neg and for ziatype you need 2.2 Drange.

With your sensitizer the Drange surely is smaller ( due to lithium Fox and Platinum)

You may nor forget that to get a good curve it may be done in 2 step, first curve will give the general contras and second curve create from the first will resove all the microcontrast problem.

Hope this help

best regards

[marko_trebusak]

Christian thank you for jumping in. Can you explain your two curve approach? And another note: as far as I know Keith is using Epson 1280 and not 2200?

Marko

[sanking]

Marko,

The first part of the correction is really at the heart of both Mark Nelson's PDN system and Clay's color point method. With both approaches you determine at the beginning process exposure scale, and then you select a negative printing color to match the ES. After that, you make curve corrections as the second part of the process.

Sandy

Christian thank you for jumping in. Can you explain your two curve approach? And another note: as far as I know Keith is using Epson 1280 and not 2200?

Marko

[marko_trebusak]

Thank you, Sandy!

Now I got it. My experiments show some light at the end of the tunnel. Basically, I'm set now. Only highlights needs some tweaking, and hopefully I'll be done till the end of this week.

But on the long run, I'll be on a market for Mark's PDF, because it's better to have a system to work with.

Marko

[Michael Koch-Schulte]

I usually can tweak the first curve to do what I need it to do, but, if you really want to try a second curve Liam Lawless outlines a method for doing so in an issue of Post Factory and I think it might have made it to a web page. It involves using the transfer function of the PS print menu. If you wanted to try a second curve using the curve dialogue I think all you would have to do is print a stepwedge out using your first curve and record the values. You'd be in a situation where you would have to apply the second curve to fine tune your first curve all the time. Maybe someone knows of a way around this ie. adding the values of the curves together to produce one curve.

Christian thank you for jumping in. Can you explain your two curve approach? And another note: as far as I know Keith is using Epson 1280 and not 2200?

Marko