printing black and white on color enlarger

t al z

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hey everyone again,

I have the have an Omega Chromega B Dichroic enlarger and I am printing black and white prints on it. Just curious as to anyones experiences with contrast filter settings. I am printing on Ilford MGIV RC DeluxeFrom looking at the Ilford Contrast Control Fact sheet:

http://www.ilfordphoto.com/Webfiles/2006130201152306.pdf

I am a bit unsure of what values to use. I see that Omega enlargers are listed under the Kodak as the type of filtration. However, should I use the values for magenta and/or yellow under the "single colour filter settings" or the "dual colour filter settings". As it states, the dual colour filter settings should need less adjustment to exposure times when changing contrast.

What are others experiences? Does dialing in magenta and yellow seriously affect exposure times? Should I use the single or dual filter settings?

Thanks in advance, the advice on here is great!
 

clogz

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Well, your big worry seems to be exposure times. From grade 0 up till and including grade 3 you can use the same times when you use dual filtration. Grade 4/5: double time.
Hope this helps

Hans
 

fschifano

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clogz said:
Well, your big worry seems to be exposure times. From grade 0 up till and including grade 3 you can use the same times when you use dual filtration. Grade 4/5: double time.
Hope this helps

Hans
Click to expand...

I'm here to tell you folks, that it ain't necessarily so. Kodak made similar claims about their filters and papers, and that didn't work exactly as they had claimed either. I've tested many papers, including Ilford and Kodak papers, with filter sets from both manufacturers. I've tested them using both single and dual filter settings with the Omega dichroic color heads, and it didn't work as advertised. By comparing test strips made through a step wedge, using the same enlarger height, lens, f stop, and exposure time, that the paper's speed was effectively faster with no filter and that the contrast range changed for a given filter or dichro filter setting.

Nope, the only way to judge is to do the tests, and the easiest way is to get a step wedge from Stouffer's and make a series of exposures on some test strips. That will tell you exactly how much more exposure you need to add relative to a base exposure made with no filter. Go with the single filter version and figure out what you need from there. It will save you from pulling the hair from your head.
 

Dave Miller

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If, as you seem to be, you are just starting printing then I recommend that you use the dual filter setting as shown on the instructions that you got with the paper. These lead to slightly longer exposure times, but this should not be a problem. As Hans said the extreme grades need additional exposure, this is also given in the instructions. When you have got used to setting the grades through the filters, and judging the effect on contrast then that is the time to worry about slight irregularities in contrast grades, and getting involved in the doubtful benefits of step-wedges. You probably already know, but it is worth repeating for others that pick up this thread, that you should adjust your exposure (by means of test strips) to give you a hint of detail in the highlights with an exposure time of around 10 to 20 seconds, (adjust the lens aperture to get into that range) then, when you are happy with that adjust the contrast, using your filters, to give a satisfactory black whilst retaining the shadow detail that you want.
Using the single filter values will reduce exposure times a little, but exposure will the need recalculating as you change contrast; so in my opinion is not worth worrying about.
Hope that helps.
 
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t al z

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thanks everyone.

Dave, indeed, I am now using the dual colour filter setting which are working out well. I didn't have to adjust exposure time that much when I increased the contrast filter (in some case I didn't have to adjust at all).

Of note, in the .pdf linked above and the notes included with the paper, the dual filter settings has a setting for a 2 contrast (41Y, 32M), but also under single filter it lists 0Y and 0M as being the 2 contrast setting. From my tests it seems like the 41Y and 32M (dual filter settings) are much more of a 2 contrast filter than when all 3 dials are set to 0. Thoughts?

I think wedges are little beyond my level right now, but I truly appreciate all these tips. Makes there be a little less hair pulling
 

Dave Miller

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Printing grades are very subjective, and merely an attempt by paper manufacturers to describe the printing range available. Don't get hung up on grades, one man's grade 2 will be another's 3. Just enjoy the process, and of course your prints.
 

TheFlyingCamera

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Another factor to consider is the brand of enlarger you are using. While they mostly fall into a couple of big groups, each manufacturer's filter set produces a given contrast grade at a different filter combination. I think the Omegas fall into the same group as the Kodak/Beseler filter set, but they may be more akin to the Ilford set. Do a google search on contrast filtration and dichro heads and you'll get more information about what I'm talking about.
 

Dave Miller

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Don't worry about asking questions, you are not the only novice printer on the forum, and others will be interested in what is being said. It's probably best to start a new thread for each subject though since this makes subsequent searches easier. If the mods feel you are "flooding the board" they will soon tell you. Before you post do try a search as you will find most questions have been asked before, although the replies may not completely clarify matters for you. If that's the case then say so.
 
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t al z

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TheFlyingCamera,

Yep, your first instinct was right. The Omega Chromega B Dichroic is under the Kodak section for filters.

Dave, I'll create another thread!
 

haris

clogz said:
Well, your big worry seems to be exposure times. From grade 0 up till and including grade 3 you can use the same times when you use dual filtration. Grade 4/5: double time.
Hope this helps

Hans
Click to expand...


I am using Meopta Color3 color head with Ilford MG papers, and above statement in my case is not true. I allways use dual (M+Y) filtration, and allways must make new test strips when change filtration. When change from grade 2 to 3 or 1 to 2 I can't use same exposure time, and when change from 3 to 4 it is not just simply doubled exposure time. I must make new test strips whenever change filtration to determine correct time.

Regards
 
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haris

And I think above stated colour head/multigrade papers behaving is reason why I have problems to calibrate enlarger exposure meters to work with enlarger colour head, and especially have problems to calibrate contrast measuring on these devices...
 

Ole

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The best way I've found to find the exposure time after changing filtration is to use an Ilford EM-10 exposure meter. These cheap (!) little things give perfectly consistent "Zone VIII" when the illumination is adjusted to give the same reading. Any change in size or filtration - I take a reading of a highlight with what I have, change everything, and then adjust the illumination (my colour head has a ND filter) to give the exact same reading. Then I expose for the same time, and get exactly the same tone.
 

haris

Yes, Ole, that was in theory what mine Jobotronic 2000 quartz and Jobo ComTime exposure meters are supposed to do, including measuring contrast. But, while exposure time is there, or needs slight adjustment, contrast is another story...

Or, I don't know how to precisely calibrate them, and that would be the real truth

I will get some filters for b/w head and they will see what is difference between colour head and "real" filters.

But, I am getting tired of colour head, and plan to change to filters definitevly. And for another reason, I like more contrasty photographs, so condensed b/w head instead of diffused colour head is another reason

Enjoy life
 

haris

Ole said:
...and then adjust the illumination (my colour head has a ND filter) to give the exact same reading ...
Click to expand...

And I allways wonder what that 4th dial on my colour head is used for ...
 
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