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  1. #1

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    Using colour head and confused

    Hi

    I've finally got a darkroom up and running for the first time in 5 years. In my previous darkroom I had a simple condensor with under the lens MG filters.
    I managed to get hold of a couple of Durst Mod70 enlargers with the colour heads plus and old L1000 that I'm fixing up.

    Last night I tried printing for the first time with the Mod70. I was under the impression that MG paper printed at a default grade (is it G2?) with no filters. So I tried a print with the colour box switched out and the exposure times were much faster than what I was used to e.g. 4 seconds for an 8x10 from a 6x6 neg. Much too fast for me. I then tried turning the lamp down but still not much luck. I then switched in the filters and adjusted them for a grade 2 and the times dropped to a manageable 9 to 12 seconds. Again I thought that with direct light MG printed at approximately grade 2 so are the filters (using Y and M) also acting as a type of ND filter? It looks as though it's going to take me a while to calibrate the filters to my purpose. Is is worth setting up the other enlarger with below the lens filters and adjusting the colour filtration to match these results or should I just do what I used to do and go with what looks right?

  2. #2
    Dave Miller's Avatar
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    Yes, the filters will reduce the light and lengthen the exposure. Ilford give two sets of filter combination, one of which gives constant (but slower) exposure times around grades 2 to 4. The other set gives faster but varible times. I recommend that you use the first set that will allow you to step through the grades without varying times too much. Enjoy the experience.
    Regards Dave.

    An English Eye


  3. #3
    Bob F.'s Avatar
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    If you do not have it already, pop along to http://www.ilford.com/html/us_english/bw.html - download and print the PDF document called "CONTRAST CONTROL" which has filter/exposure tables for the two methods Dave suggested.

    Cheers, Bob.

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    Thanks Dave & Bob. I've already got the filter settings from Ilford and they have two settings, one for just the Yellow filter and the other for Yellow and Magenta. Is there a noticeable difference between the two and which is preferable? I'm certainly noticing the difference between the condensor and the dichroic head. It looks as though I may need to go a grade harder than I used to. Is this normal due to the diffusion? A lot of my old negs were developed as per manufacturers spec. If I understand correctly I need to increase development/contrast for a diffusion type head. Can some this be achieved in film rating and exposure (e.g. I normally expose HP5+ at 320) and then using normal dev times or is it purely down to development?

  5. #5

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    The dual colour filter numbers are supposed to be speed matched. Switch from grade to grade and you are supposedly able to keep the same exposure time. OTOH the single colour filter settings aren't speed matched. The single filters will also be quicker since you'll have less filter in the light path.

  6. #6
    Bob F.'s Avatar
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    What Nick said re' the filtering... In practice, you will find you need to adjust exposure somewhat in any case because the different filter grades effect highlights and shadows differently, so the balance of light/dark is altered somewhat between grades.

    I have not made the switch from condensor to diffused, but my understanding is as you say: increase development slightly. From my limited experience (and a lot of reading...) I do not expect you will need to alter film speed as the increase in development will probably not be sufficient to change the toe of the film curve by much. However, if you find you are now printing on to grade 2 or 3 for most of your negs then you may as well stick with your development times as they are. But, I'd wait for more experienced people to chime in before I took my word for it...

    Cheers, Bob.

  7. #7

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    Thanks Bob. I've seen the rather heated discussions about different types of light source and there is a noticeable difference, but let's not get into that old argument. One advantage I am finding is that the diffuser seems to lessen dust and the like on the neg. The room I have my equipment in is unfortunately carpeted but I have put a large antistatic mat down which helps to a certain extent. I'm working on "she who must be obeyed" to fit a laminate floor in the room but our priorities, as usual, seem to differ.

    I'll plug on for the next few days and hopefully wil be able to post some examples next week. One major advantage over my previous darkroom is that with lens prices at a ridiculously low level I'm now able to print with significantly better glass than before.

  8. #8
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    Since every enlarger type has a slightly different color temperature due to the particular lamp used and the optics, the actual filters needed to attain a given contrast grade or color balanced color print will vary from enlarger to enlarger.

    Values given in tables are as useful as the 50R starting pack recommended for color paper.

    PE

  9. #9
    raucousimages's Avatar
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    Dump the color head and go back to VC filters. I tried to print B&W VC paper over the years with color heads (Vivitar, Omega and durst) with poor results. I always had less work and better results with VC filters. The only thing that comes close is my Saunders VCCE.
    DIGITAL IS FOR THOSE AFRAID OF THE DARK.

  10. #10
    Bob Carnie's Avatar
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    Keep in mind that when changing Magenta filter you will be changing exposure.

    30 magenta change + or - will equal 1 full stop change in density

    15 magenta change + or _- will equal 1/2 stop change in density.
    Yellow filter does not affect the density as dramatically as magenta in fact very little.

    When using a dichroic enlarger, changing grades with yellow and magenta will require a understanding of this.
    I think this is why a lot of people advocate the RHAnalyser in use with a dichroic enlarger head.

    I use condensor heads with VCfilters and I really only notice a big density shift when going up to G 4.
    For diffusion I have a Ilford Multigrade head which has a keypad for density and contrast control and is easy to use.

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