Being relatively new to this forum and having only sketchily trolled through previous posts, is it correct that the system cannot be applied to either PS7 or early CS ? I do not have access to a later version of CS.

ChartThrob requires CS2 or better.

Don Bryant

Ah that makes sense. So whatever COLOURED process I use, such as cyanotype or coloured print, I should automatically convert the scaned print from COLOUR to a 16BIT GREYSCALE. Then get ChartThrob to analayse the print and create the curve from there.
Thanks Don.

Hmm, now I'm confused. It's my understanding, reinforced by a re-reading of the preceding pages of this thread, that it doesn't matter what working space you choose to analyze the charts in, as long as you maintain the same settings consistently throughout the process. And that since the calibration is done in 8-bit, there's no particular advantage to switching into 16-bit before analyzing, although if your workflow calls for working in 16-bit greyscale, there's also no harm in staying in that mode. I hope Kevin's still watching this thread and can clarify. Did I misread the advice given earlier? Thanks,
Katharine

Hello all,

I just picked up an Epson R1800 and I'm wanting to create my curves for cyanotypes using Chartthrob. I've done this once before, using a borrowed R2400 and I was very pleased with the results.

I've read in other places that dialing in color is a good way to get the needed UV density in the negative.
Is this true/helpful at all, or does it even matter, as long as I'm consistant and do the same thing to my final negatives that I do to the chartthrob test pattern?

Thanks

Hello all,

I just picked up an Epson R1800 and I'm wanting to create my curves for cyanotypes using Chartthrob. I've done this once before, using a borrowed R2400 and I was very pleased with the results.

I've read in other places that dialing in color is a good way to get the needed UV density in the negative.
Is this true/helpful at all, or does it even matter, as long as I'm consistant and do the same thing to my final negatives that I do to the chartthrob test pattern?

Thanks

You can do it without using a coloured negative, but using a colour eliminates one of your printing variables. If I told you that I had a way of eliminating say temperature as a variable when you were developing your black and white negatives you'd probably be all ears, right? Well I haven't figured out the latter yet but the colour --> density range relationship has been known since Dan Burkholder published the effect in "Making Digital Negatives for Contact Printing". (See the other threads running in this forum on the arrays too. i.e. ChartThrob (http://www.hybridphoto.com/forums/showthread.php?t=36), RNP Arrays (http://www.hybridphoto.com/forums/showthread.php?t=236).) What printing an ordered array of colours does is essentially the same thing you do in Photoshop when you use the "Levels" menu to set the white point, it trims the excess head room. You could also choose more advanced method such as using a RIP method which allows you to achieve this by setting ink limits on your printer (thus setting the density range) and creating custom curves to smooth out the tonal scale. There are several books and systems you could also buy. You basically have to see what works for you. But that said all the parts necessary to achieve great results are available here for free on hybridphoto.
~m

Hmm, now I'm confused. It's my understanding, reinforced by a re-reading of the preceding pages of this thread, that it doesn't matter what working space you choose to analyze the charts in, as long as you maintain the same settings consistently throughout the process. And that since the calibration is done in 8-bit, there's no particular advantage to switching into 16-bit before analyzing, although if your workflow calls for working in 16-bit greyscale, there's also no harm in staying in that mode. I hope Kevin's still watching this thread and can clarify. Did I misread the advice given earlier? Thanks,
KatharineYes, you're correct. What you want to avoid is automatic recalibrations, but in general since ChartThrob is intended for gauging grayscale values, the color of the scan, when reduced to grayscale, should be consistent with the charting process and not a cause for alarm.

Hey everyone. Just wondering what scanners/scanning software people are using with Charthrob and what sort of scanned results they're getting (i.e. is there any affordable flatbed scanner out there that gives anywhere near a linear response out-of-the-box). I just scanned an IT8 target with my ancient Epson and the Luminance values for the greyscale patches along the bottom of the target are waaaaaaaay off from what they should read. In fact, they were still pretty far off even after I'd profiled the thing! Looks like it's time for a new one, primarily for using in the production of digital negatives via charthrob, so any recommendations would be appreciated.

Important Note: When using ChartThrob set your "Color Settings|Working Space|RGB" to Adobe 1998 :) or Adobe RGB rather than sRGB :( else you'll get less than optimal results. Off by one to three per cent in places.

~m

Important Note: When using ChartThrob set your "Color Settings|Working Space|RGB" to Adobe 1998 :) or Adobe RGB rather than sRGB :( else you'll get less than optimal results. Off by one to three per cent in places.

~m

Ah, maybe that explains the nonlinearities I mentioned earlier. I had to go into the chart and manually change the values of the squares to what they should be, because they were off by that much in many places.
kt

Yes I just noticed I had the problem. I had change my working space to match my digital camera and forgot to change it back again...

~m

Just an update....still looking at my work flow that includes scanning MF and LF negs, ChartThrob-arrays, Canon-TCFilm, CanoniPF5000 pt/pd printing...I am finding that my initial color choice in CHartThrob (R 144, G 128, B 0) --greenish-yellow---has not needed any tweaking yet. In fact all my prints seem to be about right with either straight pd or few drops of Na2 5% . I posted a scan in the gallery of a pd print that I was doing to exam tonal range and smoothness with in ahighly textured subject....

Miles

Important Note: When using ChartThrob set your "Color Settings|Working Space|RGB" to Adobe 1998 :) or Adobe RGB rather than sRGB :( else you'll get less than optimal results. Off by one to three per cent in places.

~m
I seemed to be doing well until you said this and I went back and checked ...I probably have been using the sRGB from the beginning..I plan to leave it that way until I prove otherwise...I will try a dig neg for pd print with RGB1998 to see what happens...

Miles

I just found this tool, and pleased to see that it was received well here. So maybe this is just a little bump to let newer people to the site know it exists.:D