C41 negative masking

[Fatih]

Hi all,

So I am trying to create masks for my C41 negatives. All the sources and posts I am reading suggesting that I should calibrate my enlarger head to 5000K, which is 95C 60Y in my case.

However some people says, I should also adjust filtration to cancel orange mask (which I assume I need to turn more cyan and magenta) however Ctein does not mention that at all, which is the only printed source I have at the moment.

I am trying to create unsharp masks and contrast reduction masks.

So what is your recommendation?

Many thanks,
Fatih

[Drew Wiley]

First of all, I don't think Ctein ever actually did any color neg masking for sake of RA4 printing; or at least that's the distinct impression he gave me when discussing the topic in person. He did sometimes write about hypothetical ways of doing things he never actually tested himself. His forte was exposing color negs directly onto panchromatic dye transfer matrix film. I am the one who recommended starting with a 5000K colorhead setting based on a color temp meter reading, which itself takes some patience. But it seems you've already established your own colorhead setting for that. Then you need to null out the orange mask. And since this involves a color neg, the easiest way to do that is to introduce an orangish filter into the light path exactly equal to the specific orange mask itself involved. And what could be better for doing that than a frame or sheet of that very same color neg film with no image on it, yet properly developed, so that the entire thing consists only of the orange mask itself. Then the third element I personally introduce is a light yellow-green filter like a Hoya X0 to compensate for the depressed green sensitivity of the pan black and white film itself.

It's best to fine-tune your methodology for a basic neutral contrast reduction mask first, before attempting double-negative contrast-increase masking. There are many past posts where I've explained both to a certain extent, but not differential or selective color correction masks, which make the whole topic more complicated than necessary for beginner purposes.

An ideal unsharp mask for color neg printing purposes should exhibit density over the full range of the color neg itself you intend to reproduce, but at a very low contrast or gamma, to effect the cumulative density or DMax should be no more than .30 to .45 above fbf.

[Fatih]

Thanks Drew, appreciated.

Ctein recommendation was a bit funny because he suggests 90C60M to cancel orange mask, using a Beseler. It is similar to DeVere I use in terms of filter settings and mixings so I was wondering how he was cancelling that with a nearly the same mix that I have for 5000K

But wouldn't you want to give blueish light to cancel orange mask of the film as it is the opposite colour? Why would orange light null out orange mask? Also whydo we need to null out orange mask?

[Michael R]

If you’re printing traditionally (darkroom as opposed to scanning etc) I’m not sure why you’d want to “cancel” the orange mask in a C-41 negative. The orange mask is there by design and the print materials work with it. On the other hand if you are trying to alter the contrast of specific hues in isolation using masks all bets are off. Not simple.

In calibrating your enlarger light source to approximate 5000K, assuming you are using an incandescent bulb (as opposed to say LEDs) it makes sense to me you’d have a mix of C and M, weighted toward C. The lower the colour temp of your bulb, the greater the proportion of C filtration since you need to remove more red light. A plain incandescent bulb would have the lowest colour temp, a typical halogen bulb is somewhat higher, but still well below 5000K.

[Fatih]

Hi Michael,

I have managed to get reasonable cancellation for Ektar and Portra 400 films however whatever I do, I cannot get a neutral cancellation for Fuji 400H.

I have also managed to get 5000K on my DeVere and yes they are halogen bulb and yes as you say, it is more Cyan than Magenta.

Luckily I have found some film ends to use as filters to give the correct orange lights for each mask, except Portra 160 (I will look for it) but still dont know why the light should be orangish to neautralise the mask, I thought it should be blueish as that would neutralise orange mask of the film. Otherwise, Orange light with orange mask of the film, the result will be even more orange

[Drew Wiley]

Michael - This is about exposing a color neg film onto PANCHROMATIC FILM to create a neutral-balanced supplementary contrast mask first, and NOT about the final exposure onto RA4 paper. Huge procedural difference. If the orange mask isn't nulled out when making the supplementary contrast mask, you're going to have a seriously skewed result. It's not like masking for chrome films without any orange mask, as done with Ciba or Dye Transfer printing, for example.

Yes, some of this sounds counterintuitive at first. But the reason the correction filter should be orange just like the CN film mask hue itself, is that you are creating a negative of a negative - in other words, a soft positive which acts as a neutral contrast reduction mask in this case - unless, of course, you want a selective mask biassed toward certain hues only, and not a neutral one - but that's a more advanced subject.

Certain Fuji films had a fourth dye layer. I have printed some of those films onto RA4 paper, but never with supplementary masks. And I can't go too highly into detail with my exact masking procedure because I'm doing it via a fancy RGB additive light source, which allows a level of control somewhat more precise than traditional CMY colorheads. But in general, I can say that balancing the head to approximately 5000K, and then using a supplementary filter to offset the orange mask in the original, seems to work a lot more efficiently than trying to tweak the colorhead setting to do that all by itself. I have done plenty of tests to confirm that.

And again, Ctein was giving an estimated kind of advice relative to his own Beseler colorhead, which he never seems to have actually tested. As an author, he fiddled with a certain amount of RA4 and even Cibachrome printing, but primarily practiced an uncommon version of dye transfer printing (now he does advanced inkjet work).

[Fatih]

Thanks Drew, appreciated.

So I have found Porta400, Ektar100, Fuji400H scraps that I can use as colour filter.

I need to find Gold200 and Portra160 to make sure I have those options as well. Sadly looks like I have not shot both of them badly enough that I can have a scrap part