Sirius,EXCEPT as I stated before, using only Yellow and Magenta filters CHANGE THE CONTRAST. Therefore using only Yellow and Magenta filters do not have the same effect as closing down the aperture. That is exactly as it works, even though you choose to disagree.
Using equal amounts of the three filter produce Gray which is neutral which Yellow and Magenta is not.
Sirius, will you agree that the use of filter settings at a grade two level (or 2.5ish) will yield the same contrast as white light will, while requiring more exposure time?
No - the filter settings are not linear, they are logarithmic.Does this mean that if I want grade 2 but the time is too short with 45Y and 24M I can simply double both of the dual filtrations ( 90Y and 48M)and then the paper requires double the exposure but the grade remains at 2 because the balance of Y and M has not changed?
No - the filter settings are not linear, they are logarithmic.
To maintain the same ratio of blue and green light, add the same number to each setting. 75Y and 54M will give you the same contrast, and most likely one stop less light (depending on which scale is used by your light source).
I'd expect them to be exponential, wouldn't you agree? The question (for me) is: at what rate. Power of 2? Power of 4? Power of 10? Something else? I've not yet been able to find good information on this. Does anyone have a suggestion on how to figure this out?No - the filter settings are not linear, they are logarithmic.
I'd expect them to be exponential, wouldn't you agree? The question (for me) is: at what rate. Power of 2? Power of 4? Power of 10? Something else? I've not yet been able to find good information on this. Does anyone have a suggestion on how to figure this out?
Edit: my logic may be more based on an additive system; the fundamental question still stands though.
... or if the relationship between cc''s and transmission is in practice different than the 30=0.30 relationship you mention. Do you happen to know this as well?
Does anyone know if the settings on all the different types of colour heads are actually calibrated to the same cc units?
If you are used to colour heads calibrated in CC or CP filter values, you will notice that the filters of the CLS 501 colour head have considerably higher filter densities at equivalent scale settings.
Kodak filter values need to be 1.5 times as high as equivalent Durst values for the same effect.
CIBA filter values need to be 1.5 times as high as equivalent Durst values for the same effect.
Agfa filter values need to be twice as high as equivalent Durst values for the same effect.
Thanks Mr. Bill,So it appears that there have been at least a few different scales.
30 magenta is 1 stop difference but not 30 yellow... much lessThanks Mr. Bill,
I'll try to keep this in mind whenever the "30 steps = one stop" idea is part of the discussiion.
I suspected this indeed - although I've never been in a position to verify it. Thanks once again! I may do some measurements and experiments just to get a feeling for this.So it appears that there have been at least a few different scales.
That would suggest that the yellow response of the paper is different - which isn't the case. Look at the Endura curves; they track perfectly in the linear region. Probably the same for Crystal Archive, but I'd have to check.30 magenta is 1 stop difference but not 30 yellow... much less
Did some printing yesterday and dialled in 100 of C,M,K. I didn't get the step tablet out but it seemed to knock 1/2 a grade off contrast and 3 stops off the exposure. It achieved what I wanted, to extend exposure time when printing small prints.
I would use the color head instead of the below-the-lens VC filters, according to this chart: https://www.ilfordphoto.com/wp/wp-content/uploads/2017/03/Contrast-control-for-Ilford-Multigrade.pdfI have to make some postcard size prints and I'm finding the exposure times to be ridiculously short, less than 5 seconds which isn't enough for burning and dodging. I can't stop my lens down any more due to diffraction. I'm using Ilford below lens filters. If I added equal amounts of Y, M and C that would extend my exposure times but does anyone see any problems with this?
Did some printing yesterday and dialled in 100 of C,M,K. I didn't get the step tablet out but it seemed to knock 1/2 a grade off contrast and 3 stops off the exposure. It achieved what I wanted, to extend exposure time when printing small prints.
Please read the title of this thread and my original post. I am using CMY to add density to extend print times, Contrast is controlled by under the lens Ilford filters.Adding equal parts of CMK to tweak the contrast? Sounds good.
That was my impression also but you mention K in a previous quote as in CMK and not CMY, hence the confusion maybe. It sounds like K is a typo, was it?Please read the title of this thread and my original post. I am using CMY to add density to extend print times, Contrast is controlled by under the lens Ilford filters.
Did some printing yesterday and dialled in 100 of C,M,K. I didn't get the step tablet out but it seemed to knock 1/2 a grade off contrast and 3 stops off the exposure. It achieved what I wanted, to extend exposure time when printing small prints.
Yes, it was a typo. The only "K" filter I've ever seen in a darkroom is more commonly known as a dodging toolPlease read the title of this thread and my original post. I am using CMY to add density to extend print times, Contrast is controlled by under the lens Ilford filters.
Please read the title of this thread and my original post. I am using CMY to add density to extend print times, Contrast is controlled by under the lens Ilford filters.
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