Calibrating for Carbon


#1

Im creating a new curve for Carbon, and have a couple of questions.

I have limited from the master curve and tested max black. From there I printed a 129 step table which I made a print, that print was measured using a Colorvision spyder pro and a new curve made and then printed again as a 129 tablet. Now I do expect to have to do this a couple of times but the carbon process takes a while so thought I would ask a couple of questions.

First, the first 7 segments are paper white, the 8th starts showing tone. When I take the new set of readings will it cause a issue will having the first 7 step reading the same or should I manually alter the reading a little bit to get a gradually increase so the smoother XL works.

Second , While Ive never notice a problem making Kallitype or Silver digital negs I do see grain in the highlight when printing carbon on glossy photo paper, properly because of the higher ink lay down or maybe the change from 1430 to 2880 printer. I can see it in the negative too. I assume this is because I have been using TPU PictorioPro not TPS Ultra (this has been solved by a speedy delivery, 5 day from B&H to Melbourne Aust). Anyway the question is do we think the grain will effect the SpyerPro reading to any great extent?

 

Shane

 


#2

I think since you are still seeing multiple steps of paper white that you need to lower the limit a bit more - probably 13 or 14 steps (extrapolating from the 129-step linearization target to the 255 step limiter target.) Only step 1 should be paper white.

I can see dots in the highlights of prints made from my 3880 negs (if I look for them) but not from the 1430. I think it is due to difference in dot size and dither, but the higher density range you need for carbon may be magnifying it a bit. I don’t think it affects readings in a significant way, but Walker is certainly better qualified to answer that knowledgeably than I am. :wink:


#3

Thanks Keith,

I thought I had limited it but maybe I messed it up. I’ll apply the limit points again to this curve then reprint the negative onto UltraPro and see if it improves.

 

I think Carbon on glossy is quite unforgiving…

 

Thanks fir the help.


#4

What optical transparency density are you requiring to get paper white on your carbon process?

Related to Keith’s comment, yes the QTR dither produces excess dots on 3.5 picoliter printers like the 3880 in my opinion. I’m working on fixing that but it goes well beyond just ink curves and into driver tech.

I may have a tool for you. I will email you.

 

best,

Walker


#5

Thanks Walker.


#6

Hi Shane,

I just wanted to know whether you ended up obtaining a good calibration for carbon transfer, with good detail all along the highlights? It seems that some carbon printers mention (and have shown through tests) the impossibility of printing highlights with continuous tone negatives… due to the fact there is a certain threshold at which no mechanical bond with the gelatin seems to happen, which cannot be obtained with continuous toned negatives in quite a bit chunk of the highlights… for that reason, they advocate for the use of halftone patterns (imagesetter, etc) that offer hard edges and allow light to fully penetrate through tiny holes, allowing the bond of sensitizer to the gelating structure to take place… I am curious to see whether you could finally obtain detail from step 1 in the target calibration using piezoDN after these posts? Any other member’s experience?

Walker, have you got any feedback about carbon transfer printers using piezoDN with epson pro printers?

Cheers,

Rafael


#7

I’m waiting on anyone to send me neg targets from working systems so I can build out a solution as we do not have carbon transfer facilities here.

 

-Walker


#8

Hi Rafael,

Following that post I started using the Beta version that Walker is working on but also got caught up in “other stuff” so only really getting back to it now. i fact this weekend I was going to restart the calibration process for carbon. Will let you know in due course. I think the issue is a complex one revolving around tissue density, thickness and gelatine.

 

cheers

Shane


#9

 

Hi Walker,

Can you explain what you need. maybe I can help.

 

Shane

 


#10

All I need is some step ramps from a working system (more steps the better, like 256 ideally) and examples of the best “grain” in the highlights required. I have the ability to do some nifty stuff with curve-making here but don’t have the reference materials required nor the lab to make them yet.

 

-Walker