calibrating a color head for b&w

[coops]

No. Different VC papers respond differently to a given filter set or color head setting. You can see this, for example, if you look at the data sheets for the various Ilford VC papers. Look at the section in the datasheets labeled "ISO Range".

Contrast will also be affected by your choice of paper developer.

Figures lol. Hoping the answer would be yes. I should have known better.

[ic-racer]

All the reading I have done seems to show that they are only an estimate and rarely accurate. I will not get my paper delivered until wed. so I cannot go into the darkroom and see for myself until then.

For Omega and Durst heads the Ilford table for Ilford MG papers is spot-on.

Exactly how did the table fail you? If you start, say at "2" and are too light at "3" then subtract an equal amount of Magenta and Yellow to make it match. Fine tune the chart that way, it will be easier than making a chart from scratch.

[coops]

If you start, say at "2" and are too light at "3" then subtract an equal amount of Magenta and Yellow to make it match. Fine tune the chart that way, it will be easier than making a chart from scratch.

Think I will do just that cheers

[ChrisN]

After I developed doubts about the accuracy of the contrast setting I was achieving by dialing in the two-filter settings recommended by Ilford, I took the lazy route and bought a set of Ilford multigrade filter that slip into the holder under the lens. I'm happy with the results, and changing filters is much faster too!

I think the problem I was having may have come from too-zealous cleaning of the built-in filters.

[bob carnie]

Adding cyan to a filter pack will certainly provide neutral density.

Point 1. the cyan does not actually provide neutral density. I use to think so but it was pointed out here or on APUG that that was not so. I tested and, strong or weak, blue is blue. Try it and I think you will find the cyan settings are of no effect. (within minor variations in the truethyness of the actual cyan filter.)
Point 2 the values of ilford filters may or may not be written in the bible and they may or may not be what Strand thought grade 2 should be. But that bears no relationship to what you want your picture to look like.
Ilford offers two settings for a variety of different makers. one is the basic filter setting and one is a combo setting to maintain constant times. I use the latter knowing that my old filters are faded and so I start with what I think best and go up or down in contrast as the ilford settings suggest. Fine tune and add a bit of yellow or magenta if you want a 1/4 grade change.
Just don't interchange colour head filters and gel filters. Stick with one.
Exception to the rule.
The old bakelite Kodak or Dupont #5 is much stronger than my colour head, so if I really want contrast I switch to the little under lens gizmo and the magenta #5.
Regards
Bill

[bob carnie]

If you get the results then yes. I have been split printing now for over 15 years so my methods may be different than yours.
When I started using a diffusion with dichroics along side my condensor setups I made a series of match prints, though I never used the yellow/magenta together as a blend.


I only use the yellow as a flash or a burn, I have found with my set up for straight negs *hp5 in d76*
I get a grade two with a 20-30 magenta filter for most scenes, I then will use 200 mag for contrast.
I will use 200yellow to bring in hot areas or flash areas.
For pyro negs my starting Mag pack is higher, but I am always making the first exposure on the light and flat side and then using the blast of magenta and yellow to control contrast and local contrast.
sorry I can't help you with the step wedge issue.

Thanks Bob. Am I right in saying that if, for example, I determine that say 15 secs exposure using a #2 ilford filter gets me the desired result with a step wedge, and 10Y 30 M get me the same print using the color head filters, this combination will get me a grade #2 with any paper, aperture combination? I would just need to determine the right exposure time?

[cowanw]

Adding cyan to a filter pack will certainly provide neutral density.

Keeping in mind that the magenta, yellow and cyan is a subtractive system and that they are really Minus blue, Minus green and Minus red.
Minus red, no matter how much of it, has no effect on a blue green sensitive paper.
Try it next time you are in the darkroom.
Regards
Bill

[cowanw]

Zone VI enlargers are additive and are green and blue. In this case extra green or extra blue give more exposure.
In the subtractive system the filters take away light.
Regards
Bill

[dsphotog]

I use the Ilford dual filter chart on my Beseler 45 Dichro, with great success.
Make a test strip for exposure, and if needed, dial in the change of contrast.
That system was very useful for me when printing other peoples negs, that vary in exposure & contrast.
I've done a printing test, changing only the filtration, same exposure, works great.

YMMV

[cowanw]

Bob
Here is ilford's explanation
http://www.ilfordphoto.com/Webfiles/...0201152306.pdf

Wiki sums it up like this
Variable-contrast - or "VC" papers - account for the great majority of consumption of these papers in the 21'st century. VC papers permit the selection of a wide range of contrast grades, in the case of the brand leader between 00 and 5. These papers are coated with a mixture of three emulsions, all of equal contrast and sensitivity to blue light. However, each emulsion is sensitised in different proportions to green light. Upon exposure to blue light, all emulsions act in an additive manner to produce a high contrast image. When exposed to green light alone, the emulsions produce a low contrast image because each is differently sensitised to green. By varying the ratio of blue to green light, the contrast of the print can be continuously varied between these extremes, creating all contrast grades from 00 to 5. Filters in the enlarger's light path are a common method of achieving this control. Magenta filters absorb green and transmit blue and red, while yellow filters absorb blue and transmit green and red. [7]
(Cyan filters absorb red and transmit blue and green)

Here is Paul Butzi"s site, on page 7
http://photo.net/black-and-white-pho...g-forum/00Toow

Finally, recall that black and white printing papers are insensitive to red light. Adjusting cyan
filtration adjusts how much red light strikes the paper (because transmission filters subtract their
complementary color). Because of this, for black and white printing purposes, cyan filtration
makes no difference at all, and we can ignore the cyan contribution to neutral density. As a
result, cyan filtration is ignored in the final calculations.

Shutterbug has a nice article on it.
http://shutterbug.com/columns/the_da...2sb_inthedark/

If you are using this enlarger to make black and white prints you can ignore the cyan filter. It simply adjusts the amount of red light that reaches the paper. All variable contrast paper is blind to red light. That's why you use a red safelight in the darkroom.

As I said before, try it
Regards
Bill