C41 Dynamic Range on RA4

Forgive me as this analog question is inspired from a digital workflow

I was recently scanning some Lomo800 and I noticed one frame had an incredible amount of dynamic range- such that I could only represent a full range of tones by masking off the sky by hand or using an HDR software solution. This experience informed the following question:

Does printing RA4 have some sort of HDR sort of process built into the chemical process on the paper (via, possibly, reciprocity failure)? I am curious if printing is able to capture all the tones in a way that digital has trouble, especially when the highlights would only render meaningfully when darkening the image by about 4EVs, at which point everything in the shadows and midtones would be crushed.

RoboRepublic said:

Does printing RA4 have some sort of HDR sort of process built into the chemical process on the paper (via, possibly, reciprocity failure)?

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No. Your high contrast negative will also be problematic to print on RA4.

One can use burning and dodging to deal with these sorts of situations.
It also may be the case that the characteristic curve of the paper may help deal with a part of it - any difference depends on the negative, and how you normally create and post-process your scans.

Reflective media inherently has lower dynamic range than media using transmitted light.

It is said that a good quality glossy reflection print dynamic range is in the about LOG range 1.80, or about 6 F-stops, or about 64:1 range, while LCD montors are perhaps 400:1, and some other monitors claim 1000:1 or higher.

But the dynamic range of scene brightness during shooting is a different thing than dynamic range of reproduction, regardless of media type.
You could have 13EV brightness range in scene, captured into 14-bit RAW, which is converted to 8-bit-JPG, and then it is printed on flat photographic paper vs. glossy photoraphic paper vs. offset press on newsprint vs. offset press on glossy magazine paper.

You have choices of RA4 paper. Some of it is a little punchier and more saturated and contrasty than other options. Likewise, color neg films themselves are available in a range of contrast and hue saturation levels. So you need to find a happy marriage of the two that suits your own purpose best. That is where you need to start. Basic dodging and burning is also routine. Beyond that, there are specialized controls available to experienced printers. Labs which scan the film for sake of outputting the content onto laser printers can tweak the film characteristics in PS to a degree. And people like me know how to do it all-darkroom style via specialized masking.

But to understand all this, it's best to un-hitch your digital camera experience and its kind of vocabulary and begin over, experimenting with real film and RA4 print paper. If you don't have your own color enlarger, you could seek out a lab which still does optical printing. RA4 printing and processing is actually quite easy and affordable once you've learned the basics. But avoid services like one-hour labs, or you'll learn little except how disappointed you can get.

Sophisticated contrast controls in the darkroom constitute a far more involved learning curve. That's why most color neg film shooters don't even bother with advanced technique, and stick to simply mating a happy film to a happy paper. For example, among Kodak pro films you have Portra 160, which is fairly soft with a wide exposure range, Portra 400 which is a little more contrasty and saturated, and Ektar 100 which has distinctly punchier color, but also somewhat less exposure latitude. Which types of hues in nature reproduce well, and which do not, is a complicated topic; so you'd have to be more specific about your actual intentions. Most CN films are engineered for good skintone/portraiture applications, however.

You're not going to find much about that kind of topic that's anywhere remotely up to date. Too few of us do it in this manner. Some of the old Kodak Color Printing guidebooks do briefly outline variations with the films then available. I happen to come from a Cibachrome printing background, where masking technique was essential, so already knew the basics and already had the equipment, although color negative film involves recalibration of the whole idea.

Old Gregg said:

I don't have the means to set up a darkroom, but would love to read more about this. Anything you can recommend/link to? Thanks.

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Ctein's Post Exposure.

Ctein mentions very little about masking in relation to RA4 printing. He apparently never tried it, based on what he told me in person. But I should visit him again one of these days for another chat, and show him some samples, especially since CN films have changed quite a bit in recent years. His specialty was dye transfer printing using Pan Matrix Film, the less common version of dye transfer which didn't involve intermediate color separations onto black and white film, but direct enlargement of color negatives onto the three sheets of panchromatic film which received the dyes, subsequently transferred that to the special receiving paper. He might have been the last person doing that particular method, since the necessary Pan Matrix Film has never been replicated since Kodak quit making it. He does explain masking generically a bit, and did some testing relative to masks with Cibachrome at one point.

The problem with CN film masking is that you've already got an integral orange mask in place doing most of the heavy lifting. So supplementary masks have to be quite subtle because just a little goes a long ways. It's a lot like power steering on a car. You can either do conventional contrast reduction masks if the original is too contrasty, or a contrast increase mask via the double-neg method (a b&w film inter-positive is made from the color neg original, and this in turn is used to make a gentle supplementary b&w negative, which is then registered to the color original to increase printing contrast). There are many other tricks possible.

In past threads I've explained the need for a very low contrast developer and appropriate film for sake of these kinds of masks. Ctein had a low-contrast brew he called Muir Softshot, and provides the formula in his book, Post Exposure; and I have my own special elixir. Either FP4 or TMax100 can be turned into excellent masking films. TMX is better for smaller originals due to its finer grain. But because the orange mask on the original has to be factored, there are certain filtration hoops you have to jump through to do it right, which I won't take time to explain here.

You may want to check your scanning software and configuration. Some of it can get a little "trigger happy" with the histogram if you're not careful. Color negative film has quite a _low_ DMax relative to a slide film, so even the most hideously botched C41 negative shouldn't be problematic for scanning. With my Epson V850 I'm able to capture the full dynamic range in 48 bit color and then adjust later for final contrast, including areas in full shadow all the way to blistering direct sun. If you're not able to do that your scanning software should be the first place to check.

These days with the paper choices you basically only get one, so unless you want to get crazy you need to expose the negative correctly for printing. Back in the 2011 era I would print on Kodak Supra Endura at room temp and it looked great well-exposed off a matrix meter. I'm quite tempted at present to set up another color darkroom and run 20x20 hasselblad negatives onto Endura Metallic... the scanner resolution is crap compared to a real enlarger, sorry to say.