Scanning step wedge with DSLR

[Neil Genower]

To create a suitable digital negative for palladium printing, I need to follow a series of steps for a QTR curve.
I currently don't own a flatbed scanner, is it possible to scan the printed step wedge using a digital camera?
I'm wondering if the camera's profile will affect the natural look of the wedge. If I shoot using the TIFF setting, might that work? In grateful anticipation of a solution.

 

[koraks]

Sure. Just create a decent lighting setup. There's all kinds of manuals/howto's on art reproduction that apply to your situation. It can be as simple as a tripod and a north-facing window or as complex as strobes with cross polarized gels, dedicated flat field curvature lenses, color profiles etc..
As to the "neutral color", I'm not sure if I see the problem. Just desaturate? After all it's a density exercise and the color/tone isn't all that important for this procedure anyway.

Have you already tried it? I usually just give it a go and then solve the problems I run into.

 

[Neil Genower]

Thanks Koraks. I haven't tried it, but in various tutorials the users all have flat beds. I understand it's a density calculation. I see now that it's perfectly reasonable to scan this way, I have a tendency to overthink things and I have just done it here. Thank you for your reply, appreciated.

 

[koraks]

Sounds good. For these kinds of curve calculations, what you need to establish is the white and black points and you need a decent degree of linearity in recording the fields in-between (i.e. the various gradations of grey). Things that are not very important are for instance color rendition, sharpness, angle/geometric distortion or even contrast; it's kind of OK if the strip ends up occupying only part of the histogram of the digital file. You can always correct that in post processing. That's what happens with scanning as well anyway; it's just a low contrast original with some digital gain applied to it. The only challenge you face with a digital camera is evenness of illumination and prevention of things like gloss/specular highlights. The latter is usually not a big issue and the former can be tackled by using a diffuse light source - and basically just keeping your eyes open for any problems...

Good luck, I found digital negatives an accessible way of exploring alt. process printing. All the calibration stuff in the end bored me, though. I recently threw out the stacks of cyanotypes, Van Dykes etc. I must have made thousands of calibration strips over a fairly short period of time.

 

[Neil Genower]

It's all new to me. I have researched quite extensively (probably too much) and found a very thorough tutorial online from ' North Light photographic workshops; (Bill Schwab) to make digital negatives for pt/pd printing via the Ware malde method of POP. It's a relatively complicated process and I didn't want to negate it's value by incorrect scanning of the test strip. I've no problem with evenly lighting the test, but correct exposure is important and will take a reading from a grey card. On a separate note: I'm in the UK and the only suppliers of pt/pd salts seem to be in the USA, is that correct/ Appreciate you taking the time.

 

[koraks]

Sounds good. Yeah, the well known suppliers are in the US but usually alternatives can be found in Europe. Theres an Italian outfit that sells this kind of stuff but I forgot the name. And I'm sure there are others across the continent. It's just that the US ones are more well known due to their online presence and mostly the fact that (American) practitioners talk a lot about them online.

 

[Neil Genower]

Yup, most seem to be in the US. I'm fine with that, I only need the pt from there (Bostick & Sullivan) the less salubrious chems I can get from various places in the UK, like the clearing baths and ammonium ferric oxalate. Odd though that you can't seem to find any pt or pd in europe. I did find the Italian one but I didn't see any metal salts.

 

[koraks]

I never looked very hard for Pt or Pd salts, but I did at some point buy some Pd salt from a contact in Eastern Europe. I think it was Romania. But I wasn't specifically looking for it at that point.
There's no doubt in my mind that there are some stores retailing this in Europe to consumers, but it's a small market in a linguistically divided continent.