How to improve the dark details on my Pt/Pd print

[Andrew ren]

Hello all,

Got some problem with my Pt/Pd printing.

I am using the digital negative approach to make my contact prints.

now, the same file, scanned from 57 tmax, is printing fine by my epson 3800 on silver rag, all sorts of nice deep dark details showing on the inkjet print.

but the same file, got pitch black on the Pt/Pd print, I tried to open the shadow a little bit in the Photoshop and re-adjust the level, the curve, just can't get it right, at least to my eye. i mean the black is blocky, ugly looking.

is that hard to get a nice deep dark details on Pt prints? I knew that Pt is good on the middle/upper tone..

Jim.K, my friend on this forum suggests me to over-expose, say, zone 3 to zone 5, then N-2 to get all the dark details i need on the Pt print, and meanwhile you can adjust them in the Photoshop to get a darker detail on the digital print...

any ideas?

Cheers

Andrew

[Steve Sherman]

Hello all,

Got some problem with my Pt/Pd printing.

I am using the digital negative approach to make my contact prints.

now, the same file, scanned from 57 tmax, is printing fine by my epson 3800 on silver rag, all sorts of nice deep dark details showing on the inkjet print.

but the same file, got pitch black on the Pt/Pd print, I tried to open the shadow a little bit in the Photoshop and re-adjust the level, the curve, just can't get it right, at least to my eye. i mean the black is blocky, ugly looking.

is that hard to get a nice deep dark details on Pt prints? I knew that Pt is good on the middle/upper tone..

Jim.K, my friend on this forum suggests me to over-expose, say, zone 3 to zone 5, then N-2 to get all the dark details i need on the Pt print, and meanwhile you can adjust them in the Photoshop to get a darker detail on the digital print...

any ideas?

Cheers

Andrew

Hi Andrew,

I am fairly new to PT / PD printing but do remember that the dark values of a Pt / Pd print will dry down considerably from what you see while still in a wet state. I think much of what you need is to balance the high value and dark values through your developer contrast knowing the dark values will darken considerably when dry.

Also, I remember that for larger areas of dark tone many printers use a solution of "Tween" to even out the dark values you describe.

Hope this helps

[Jim Michael]

Doesn't pt have a different curve that pt/pd? If so I think the digital negative production process should be recalibrated for pt and include your step wedge in the test print in order to establish that any issues are with the negative rather than the chemistry.

[Andrew ren]

Steve,

you knew me, I am doing things in Photoshop :-0 but not too much though.

the problem is the "file" looks good on my calibrated screen and print well on the silver rag on the epson 3800.

Jim,

yes, I did the test pretty consistently, the ratio of Pt/Pd, the temperature of the Potassium developer.. and so on.

the only thing i noticed is that the uncovered the coating area is still slightly lighter than the covered area(by OHP) even @ 275units on my nuarc 26-1k. so you are right, I have to redo everything, start from 200units, then rebuild the curve. but this will only fix the solarizing problem, not the dark detail.

Andrew

[Colin Graham]

I'm not really clear what your workflow for digital negatives is, so it's hard to tell how to help. How did you arrive at your curve for pt? Are you using the epson driver and composite black ink, or a color negative system like PDN, or a RIP like Quadtone Rip?

You might want to check out this site- hybridphoto.com- there is an entire subforum devoted to digital negatives.

[Andrew ren]

Colin,

first and foremost, is the base exposure, as i mentioned, 275unit on my nuarc.

then print the step wedge with QIP, with no curve modification, raw scanned. and build the correction curve based on the scanned file.

[Andrew ren]

next, print the step wedge with QIP with this newly built correction curve. scan it and double check the file, the input and output value.

[Colin Graham]

If your using QTR and need more shadow separation, you might want to adjust the LK inkset (density and limits) to give more of a boost in the 90-100 step range. That's often the most difficult area to curve. I usually try to get a much more linear response in the 0-20 steps and 90-100 steps just with ink densities and limits before I even start to curve.

[Andrew ren]

to me, the I/P and O/P are pretty much matched and seems quite linear.

so the correction curve is a working curve. to me.

and also, any value higher than 95% ON THE STEPWEDGE(from 95-100) is rendered as pitch black on my print. but not on my digital print. same "file"

Andrew

[Colin Graham]

I'm a little confused about the two separate curves. Are you using them in sequence somehow? Did you change the ink profile between them to get a more linear response?

But maybe try printing a wedge with a longer range of tones in the problem areas. Smaller wedges with 5 step increments might be trickier to tweak with small inconsistancies of sensitizer, etc. If the step is printing correctly but similar tones in your image file aren't, they may be blocking up in areas hard to nail down with shorter step tablets.