# Started dark room classes last night



## the_peel (Sep 30, 2004)

Hi all, 

I started taking dark room classes last night at a high school.  The thing runs for the next 7-8 weeks, so I have plenty of time to play around with the equipment.  I was stupid enough to bring an undeveloped roll of color film I finished shooting last weekend, just to find out they wanted BW.  

Well the @#!$ course book just said "bring a roll of film"!

Anyways, the night was a blast, even though I had to sit through it while everyone else got to play around with their negs.  I pretty much have the basics down, but just a few more questions for you pros that I didn't think about till this morning.

1) How do you dispose of those chemicals?  The guy used T-Max neg developer...  Ilford multigrade print developer...  some other stuff I can't remember (I wrote them down!).  

2) HOW do those filters on a condenser enlarger work?  What is their purpose?

3) The instructor printed one print from a BW negative using a dichroic enlarger.  On the dials, he set cyan and yellow to 0, and magenta to 25, I think.  I really had no idea why he did that.  Can someone explain to me why he set magenta to 25?  

I'm such a noob at this!    Thanks for any responses!


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## oriecat (Sep 30, 2004)

Most chemicals are safe to dispose of down the sink drain.  Some kinds of toner should not be though.

I've never used the enlargers with the built in color dials, so I can't help with that......


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## rangefinder (Sep 30, 2004)

The use of filters in a dichroic color head is to take the place of polycontrast filters when printing on polycontrast paper.

There are graded papers where the contrast is specified (i.e. contrat 2, contrast 3) and polycontrast papers where the contrast of the paper is determined by the used of a filter (most look somewhat purple-magenta).

In the manual that comes with the enlarger and/or the instructions and/or the data sheet with polycontrast paper there is a chart that specifies the contrast numbers and the approximate filter combination to achieve that contrast.  This may vary between paper and equipment manufacturers therefore this combination may not be exact.

If I remember correctly, polycontrast paper, printed without a filter, gives a contrast rating of zero (0).  Years ago there were polycontrast papers and variable contrast papers - same, same.


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## ksmattfish (Sep 30, 2004)

Magenta adds contrast, yellow lowers contrast.

EDIT:  at least with multigrade papers


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## ksmattfish (Sep 30, 2004)

the_peel said:
			
		

> HOW do those filters on a condenser enlarger work?  What is their purpose?



They control contrast.  I can't explain it in detail, but multigrade papers are designed to respond differently to blue and green light (the opposites of yellow and magenta).


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## oriecat (Oct 1, 2004)

I thought multigrade paper without a filter was a 2 or a 3?


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