Fomatone MG 132 contrast control with LPL enlarger

koraks said:

First of all, the paper you use is variable contrast and not a fixed grade 2, so in principle you're correct in trying to use filters to manipulate contrast. In my experience, Fomatone responds as expected from any VC paper to variable contrast filtering (whichever approach used, whether it is blue/green or magenta/yellow). You mention you want to do lith printing, but is that also what you're currently testing with or are you making regular prints on this paper first only to move on to lith in the future? Keep in mind that in lith, usually we control contrast by varying the intensity/duration of exposure and the duration (and strength) of development. Combining it with variable contrast filtering works fine of course, but is usually not necessary if the negative is of fairly average contrast.
Are you testing with your paper negatives that you have posted about earlier or a regular negative? I'd start with making a normal print with a regular film negative to get the basics right before introducing more deviant variables, so to speak (paper negatives, lith printing).

Since the problem description is not very specific ('uncontrolled' could mean many things) it's kind of difficult to give specific advice, but given that your enlarger works well with other papers, it should work perfectly fine with Fomatone as well. It's a warmtone paper, but in terms of how it works when enlarging onto it, it's just like any other paper. Only about 2 stops slower than most neutral tone papers, but you figure that out when doing test strips.

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Laci Toth said:

So the instruction says: ‘the contrast grade of the paper is grade 2(special), if no colour filtration is used’. Is this mean if I use colour filtration then it has variable contrast?

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Laci Toth said:

So the outcomes were flat and bright white or blurred

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koraks said:

This means: the paper is about grade 2 when using unfiltered light from an enlarger bulb, and it has variable contrast when filters are used.


'Blurred' implies it's not a contrast issue but some other problem, such as a light leak in your enlarger (light passing along the sides of the negative onto the paper or something like that), bad focus/alignment, etc.
Bright white and flat suggests insufficient exposure, possibly combined with too low contrast setting for the negative used.

You are developing the paper to completion and not pulling it early from the developer, I assume? Just checking.

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cowanw said:

It does seem odd that the paper would be grade 2 with white light AND grade 2 with 20 magenta. Ilford's data sheet says LPL is as Kodak's numbers are and specifies 0 Yellow and O Magenta for a grade 2. I like the combination settings which is 41 Y and 32 M

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Laci Toth said:

To be honest I’m totally confused as to what colours and numbers should I use. Just magenta? Just yellow? Which number? What works with Durst and Meopta would work with LPL/Kodak? 20M for Durst/Meopta is 32M for Kodak. What if I’d like to decrease the contrast? Should I just use less magenta or just yellow? The info says grade one for this paper for Durst and Meopta is 20Y but I couldn’t even find it’s equivalent for Kodak. Grade one for Kodak is 68Y and 10M. But the equivalent for this for Durst is 75Y and 10M. So why is the 20Y? As I understand I only have to use yellow or magenta but how? Or should I just experiment until I work it out? Seems a bit odd to me.

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cowanw said:

"20M for Durst/Meopta is 32M for Kodak"

Ilford's info sheets have two different Dursts; a max of 170M and of 130M
Ilford's data says a durst (170) of 20M is a Durst (130) of 10M and a Kodak of 5M and a Meopta of 20M. Your LPL is a kodak type enlarger. Use Kodak settings. See and read this.
https://www.ilfordphoto.com/amfile/file/download/file/1824/product/745/
Use the Ilford data.
The Foma data cannot be right if they are saying white light and 20M are the same grade.

"What if I’d like to decrease the contrast? Should I just use less magenta or just yellow? "

The settings for single colour (either yellow or magenta) revolve around grade two (no colour filter) So if using that technique, between grade 00 and grade 2, you are manipulating the strength of the yellow filter, so increase the yellow (to filter out more blue light) to decrease the contrast. Between Grade 2 and 5 you are manipulating the strength of the magenta filter. More magenta is less green light hitting the paper and therefor more contrast. The times may change at each setting.
The settings for dual colour filters revolve around using both filters to try to keep the times (seconds) the same for all the grades. Again, more magenta and less yellow is more contrast. less magenta and more yellow is less contrast.

"Grade one for Kodak is 68Y and 10M. But the equivalent for this for Durst is 75Y and 10M. So why is the 20Y?"

Dual colour settings and single colour settings are two different techniques.
You have an LPL enlarger. Stop with the Durst.

"Or should I just experiment until I work it out?"

It is good to understand that you are actually filtering out blue (hard) and green (soft) light by using yellow and magenta filters. It would be useful to take a grade 2 negative (or better yet a Stouffer test wedge negative)
http://www.stouffer.net/Photo.htm
and do six prints at each of the 00 to 5 using Kodak settings on the Ilford data sheet and you will see what the effects are in your own darkroom.

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adelorenzo said:

For lith printing you don't use contrast filters, just white light. You control the highlights by exposure and the shadows by development.

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Laci Toth said:

Thanks for the info! I’ve the Kodak settings but the paper’s info sheet made me confused. But now based on what you’ve said I ignored the Foma’s advice and gave the dual filtration a go. It seems it works.

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adelorenzo said:

For lith printing you don't use contrast filters, just white light. You control the highlights by exposure and the shadows by development.

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mshchem said:

This is definitely the way I would go. I've been doing this for last 20 years with a dichro head. That paper is AMAZING, Foma makes great paper even if they have problems with instructions. Fomatone responds dramatically to Selenium toner.
The mixed filtration allows you to adjust contrast with constant exposure times. Enjoy!

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MattKing said:

It is important to understand that the filtration numbers for the various scales are essentially arbitrary - they aren't a measurement of colour, but rather just an indicator of how far you are along the colour adjustment scale used by that group of enlarger light sources.
Sort of like the measurement numbers on the side of a graduated cylinder that is quoted in both metric and non-metric units - 240 ml is the same volume as 8 ounces.
So your first job is to determine how the numbers on your light source should be read - as the same as the enlargers using the Kodak scale, or the same as the enlargers using the Durst scale with Magenta going up to 130, or the same as the enlargers using the Durst scale with Magenta going up to 170, or ???
Once you do that, you can decide whether to use the single filtration approach, or the mixed filtration approach to vary contrast. I like the mixed filtration approach because of the speed match, but both work well.

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koraks said:

The bit you copied from the Foma datasheet is indeed inconsistent and therefore confusing if you attach too much value to it. Which I just wouldn't do. Assume that for all intents and purposes:
* White light gets you somewhere close to grade 2. That may be 2, 1.5 or 2.5 or somewhere in-between depending on the paper and light source used.
* Full magenta filtering gets you the hardest contrast you can make. This will generally be somewhere between grade 4 and 5.
* Full yellow filtering gets you the lowest/softest contrast you can make. This will generally be somewhere between grade 0.5 and 00.
All the intermediate grades are available by adjusting the filtering.

How much filtering to apply exactly for a specific 'official' grade is something you could try to test, but you could also work in a more informal way and just go by the rule that more magenta or less yellow = increase contrast and more yellow or less magenta = decrease contrast.

So if you start with a 'new' negative and make a test print with no filtration and you find the contrast is too hard, dial in some yellow and make a new test strip. Conversely, if it's too soft and you want some more contrast, start dialing in some magenta. The table in the datasheet (in this case Foma's, but Ilford have similar charts in their datasheets) give you a rough feeling for how much filtration to apply, but in practice, it's really quite arbitrary. After all, nobody says you should try to work in exact increments of a whole or half a contrast grade. So what if you end up printing your negative at grade 2.57? If that's what it takes, so be it. In my experience, changes of less than half a grade are usually not really required, so getting it 'sort of right' is usually more than good enough. If you're feeling frisky, feel free to try and getting the contrast *just right*, but I personally am satisfied when I'm pretty darn close, and half-grade steps happen to be good enough for that. YMMV of course.

So don't worry too much about exact grades, and just see your color head and its Y and M filters as a means to get from very hard to very soft and anything in-between. Do keep in mind that when changing contrast via filtration, you will need to re-establish the exposure time, so when adjusting contrast, make a test strip to figure out what your new exposure needs to be.

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