Making my first digital negs

Jarvman · Mar 1, 2009

I have a question about quadtoneRIP. Do you make the original adjustment curve outside of it in Photoshop or is there a way of creating the curve in the program.

donbga · Mar 1, 2009

Jarvman said:
I have a question about quadtoneRIP. Do you make the original adjustment curve outside of it in Photoshop or is there a way of creating the curve in the program.

Linearization is done in QTR. Further tweaks can be made using a PS curve. IMO the QTRgui interface for the PC version is a much nicer working environment than the MAC version.

Don Bryant

Ron-san · Mar 1, 2009

Jarvman said:
I have a question about quadtoneRIP. Do you make the original adjustment curve outside of it in Photoshop or is there a way of creating the curve in the program.

Jarvman

In the QTR workflow I advocate, using the normal Epson K3 inkset, tonal adjustments to the final print are done in three stages.
First, the ink limits of the dark inks are adjusted to make the contrast range of the negative fit the contrast range of the photo process you are printing with.
Second, the ink limits of the light inks are adjusted to bring print tones into rough linearity. These first two steps are accomplished by inserting different number values into a textfile that specifies a QTR profile.
Third, a Photoshop .acv curve is derived that is applied to the ink settings and brings print tones into complete linearity. This Photoshop curve is also inserted at the proper place in the textfile.

This is all described, perhaps in more detail than you want right now, in the QTR Manual that can be downloaded from my website (www.ronreeder.com).

Hope this helps. Cheers, Ron Reeder

Jarvman · Mar 4, 2009

Know if anyone can point me to any pre-made curves as a starting point using bostick and sullivan's sodium chloroplatinate kit with ammonium citrate developer. I'm itching to make a full print. Would Any of Burkholders curves on his CD or website ok. I'll compare them to a custom curve I'm trying to make then.

PVia · Mar 4, 2009

Jarvman...

Use Ron's QTR palladium curve for QTR (see his site the post above yours), it is as close as you will ever get for a pre-made curve for the Epson 3800 and Pictorico or Arista OHP.

If not, use ChartThrob to get your curves...very good system and accurate. If you put in the time, you will be rewarded.

donbga · Mar 4, 2009

Jarvman said:
Know if anyone can point me to any pre-made curves as a starting point using bostick and sullivan's sodium chloroplatinate kit with ammonium citrate developer. I'm itching to make a full print. Would Any of Burkholders curves on his CD or website ok. I'll compare them to a custom curve I'm trying to make then.

Sorry if I miseed this, but what printer are you using?

Don Bryant

Jarvman · Mar 4, 2009

It's an Epson 4800 in college I think. I'm going to give that ChartThrob a whirl. It looks pretty good.

sanking · Mar 6, 2009

Before you use Chart Throb you must first determine a standard printing time and a color that matches the needs of your process. You could do the first with either PDN or with MKS's color array.

You could also just download Ron Reeder's QTR profile for pure palladium and figure out a printing time. You can assume that his profile has the right blocking density. Then, if you like you can make a print with the profile on the ChartThrob step wedge and run the analysis. It will probably indicate that you are close to linear in results, but if not you can apply the .acv curve to your positive image, before inverting, and then print with the QTR profile.

Sandy

Jarvman said:
It's an Epson 4800 in college I think. I'm going to give that ChartThrob a whirl. It looks pretty good.

Jarvman · Mar 6, 2009

My standard time appears to be 25 minutes. It seems a pretty long time but I'm getting a solid black, a clean white (which means the UV blocking density is fine?) and a good range of mid tones on the ChartThrob step wedge. This is printing using photo black ink. that pictorico seems to need a while to expose through. using 9 25W UV bulbs at about a 6" distance anyhow.

PVia · Mar 6, 2009

Jarvman...25 min is long.

Are you using CLEAR OHP or the WHITE FILM OHP?

Or maybe it's just the nature of your UV unit...

carioca · Mar 6, 2009

Jarvman said:
My standard time appears to be 25 minutes. It seems a pretty long time but I'm getting a solid black, a clean white (which means the UV blocking density is fine?) and a good range of mid tones on the ChartThrob step wedge. This is printing using photo black ink. that pictorico seems to need a while to expose through. using 9 25W UV bulbs at about a 6" distance anyhow.

Bulbs or tubes?
If it's tubes, you could reduce to 2" distance and gain in shorter exp. times.

Sidney

Jarvman · Mar 6, 2009

clear OHP :| The guy's exposure box I based mine on uses the same design and his takes 8 mins on average apparently, but that's with film not inkjet material. The film appears to have quite a white sheen to it though. I should double check. I haven't printed with a proper neg yet, should find out next week what they print like.

This stuff... http://www.bostick-sullivan.com/cart/product.php?productid=1011&cat=170&page=1

PVia · Mar 6, 2009

Try what Sidney says...I've heard 2-3"...

Myself, I'm using the So Cal sun...I'm lucky that it's very reliable!

sanking · Mar 6, 2009

Would you describe how you are determining optimum printing time?

Sandy King

Jarvman said:
clear OHP :| The guy's exposure box I based mine on uses the same design and his takes 8 mins on average apparently, but that's with film not inkjet material. The film appears to have quite a white sheen to it though. I should double check. I haven't printed with a proper neg yet, should find out next week what they print like.

This stuff... http://www.bostick-sullivan.com/cart/product.php?productid=1011&cat=170&page=1

Jarvman · Mar 7, 2009

With a test strip, covering one side of the sensitized paper with pictorico OHP and leaving the other side bare then exposing in increments of 5 mins masking with a piece of off-cut black darkroom paper bag. I'm determining the optimum time as when the area under the film is as black as the darkest area on the bare side.

sanking · Mar 7, 2009

If you are not already doing so make sure that you have at least two steps of Dmax that merge visually. This will assure that you are indeed getting maximum density. Then for exposure you can back off as necessary to avoid compacting the shadows. Some people actually like to over expose and make the correction in the curve to obtain the absolute maximum Dmax possible. What you will find is that the drop off is not sudden but very gradual. For example, you might have one step read log 1.56, the next 1.60 and the next 1.62. Visually there won't be much difference, if any, between the three readings.

Sandy King

Jarvman said:
With a test strip, covering one side of the sensitized paper with pictorico OHP and leaving the other side bare then exposing in increments of 5 mins masking with a piece of off-cut black darkroom paper bag. I'm determining the optimum time as when the area under the film is as black as the darkest area on the bare side.

Jarvman · Mar 9, 2009

Here is the scan of my step tablet, it looks ok to me but for some reason the curve it's producing is off the wall. Too dark?

sanking · Mar 9, 2009

Basically you don't have enough blocking density in the negative for the process. So in order to pull the highlights in your shadows are well over-exposed. For this process you need to produce a negative that has more blocking density.

Sandy King

Jarvman said:
Here is the scan of my step tablet, it looks ok to me but for some reason the curve it's producing is off the wall. Too dark?

Jarvman · Mar 9, 2009

gah! So how am I supposed to go about rectifying this?

Colin Graham · Mar 9, 2009

Is that the post-curve step, or just the plain linear one initially used to generate the curve in chart throb? You say 'the curve it's producing is off the wall', so I'm not sure where this step tablet is in your testing.

sanking · Mar 9, 2009

Bascially, you need to use a longer exposure scale (ES) process for the negative you are using. If you are using a pt/pd mix drop the pd and try again.

Alternatively, you could re-make the negative to have higher UV blocking. As I advised before, use PDN or download MKS's color array and carry out tests for UV blocking.

There are three steps.

1. Determine the printing time for your process.
2. Determine the color array that gives white on your step wedge.
3. Make a correction curve.

You can do the first two steps with PDN or MKS's color array. For the second step use Chart Throb. However, until you understand apply the logic of steps 1 and 2 Chart throb is basically useless.

Sandy King

Jarvman said:
gah! So how am I supposed to go about rectifying this?

Jarvman · Mar 9, 2009

I'm using a hell of a lot of materials in doing this and haven't got a decent neg yet. I never realised how time consuming and frustrating making digi negs would be, let alone sifting through all this new information. I've done it backwards again, should have tried the MKS colour array before making the neg buy wasn't aware of it. Doesn't help that I'm having to do this between home and college. I'd use PDN if it wasn't so rediculously expensive. Is it worth getting? Will it stop me wasting all this material? Maybe I should just stick to palladium and the existing QTR profile.

sanking · Mar 9, 2009

Do what you like. I am simply telling you what you need to do to optimize results.

I don't sell any of these methods for making digital negatives. Just offer advice.

If all you want to do is make some kind of print you can do that without any kind of curve or concern about UV blocking of your process.

Finally, I would say yes. Stick to pure palladium and use Ron Reeder's excellent profile. Most people who do pt/pd eventually migrate to pure palladium anyway.

Sandy King

Jarvman said:
I'm using a hell of a lot of materials in doing this and haven't got a decent neg yet. I never realised how time consuming and frustrating making digi negs would be, let alone sifting through all this new information. I've done it backwards again, should have tried the MKS colour array before making the neg buy wasn't aware of it. Doesn't help that I'm having to do this between home and college. I'd use PDN if it wasn't so rediculously expensive. Is it worth getting? Will it stop me wasting all this material? Maybe I should just stick to palladium and the existing QTR profile.

PVia · Mar 10, 2009

Jarvman...

Here's what my chartthrob wedge looks like.

http://www.flickr.com/photos/viapiano/3180317853/

If you are using a 3800 to print the negs with, Ron's QTR profile for palladium is as close as you're going to get for an excellent starting point, then tweak from there. You mention using the 4800. I don't think that this profile will get you the results you're after. This stuff is pretty specific.

Yes, it takes a long, long time to dial in the whole digi-neg process. There are so many variables in the pt/pd process alone, before even trying to add digi-negs to the mix. It took me 3 months of constant printing and study to get to the point where I could be semi-confident of my results, and there are still days where things take a left turn. I also started with traditionally enlarged negs so I could learn that process and gain insight there.

I feel that pt/pd with or without digi-negs is a lifetime pursuit. There is so much to learn and the variables with materials, environmental conditions and more are daunting.

nocrop · Mar 10, 2009

So, how does all this stuff look as a final print? Pardon my arrogance and ignorance, but surely all this intermediary digital dithering can't possibly create anything approaching a "real" contact print, right? Like how does the all-important tonal gradation look?

Making my first digital negs

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