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  1. #1
    El Gringo's Avatar
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    Ilford MG filters with Jobo|LPL C7700

    Since I acquired my Jobo|LPL C7700 Pro I have been using the colour filters built into the head to control contrast with VC papers but I have the feeling that I'm not getting as much contrast as I could be out of my negatives.

    As a point of reference I was looking through my copy of Lee Frost's 'Simple art of Black and White Photography' where he has small pics of the same neg printed at grades from 0 to 5. With my current setup, even with the magenta set to full I don't think I can even get a proper grade 3 out of my negs. I am assuming that as the built in filters are old, quite well used and they may have faded, so I was toying with the idea of buying a set of MG filters to use instead.

    The question I have is that there is a yellow leaver on the side of the enlarger's head that moves the diffuser up so you can get the neg carrier out easily, it is then lowered down when you put the neg carrier back to apply a little pressure to keep the negs flat, however, I was wondering whether I could buy a set of MG filters that normally go in the filter drawer but put them on top of the neg carrier instead. Can anyone see any problems with this? Could it damage the filters etc? Or should I just go for the below the lens filter set instead?
    Rhys

  2. #2
    ath
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    Hello Rhys,

    I stepped up from the bw LPL to the LPL7700 (in my case a Kindermann 707 color) with colourhead.
    The filters in the head are dichroic filters and do not fade over time (it is an interference effect that filters and not a dye). This is a big plus compared to the drop in filters.

    The light from the C7700 is very soft because of the diffuse light without condensors. I ended up to adapt my negative developing.
    This is quite normal.

    If you want to use the filter sets you can but the specific set for under the lens mounting or just juse the drop in type (clean of course) and mount it e.g. with cardboard under the lens. I just mounted the red filter of my old enlarger under the lens, removed the filter glass and place the VC filter on the holder when I like to.

    I'm not sure that this will give higher contrast. I suspect the root cause is the diffuse light and not the filtering.
    OTOH it is known that the #5 filter can give a little more contrast than the max. magenta of a colour head.

    I think the best solution is to adapt the negative developing to your enlarger.
    Regards,
    Andreas

  3. #3
    Bob F.'s Avatar
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    The heat from the lamp should be OK for a filter placed on top of the negative and although a bit fiddly, should work OK but you will need to check for physical damage as the lever is depressed.

    However... Dichroic filters do not generally fade. As I understand it, they are made using an optical coating of a diffraction grating, not by using coloured dyes so although mechanical damage might damage them, light will not fade them.

    Looking at the MGIV data sheet, it appears a max grade 4.5 should be available. I have a C7700 and it gets as high a contrast as I can handle on MGIV.

    If most of your negs print reasonably well with no filtration (= grade 2-ish) on MGIV then your negative contrast will probably be about right but if you find yourself needing higher of lower grades a lot, you may consider changing your development times.

    Good luck, Bob.

  4. #4
    Martin Aislabie's Avatar
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    Rhys, I use a below the lens set of MG Filters on my colour head.

    Part of it is - I've always done it this way & the other is not all enlargers can get to full G5 with their colour filter head.

    Swapping the filters in & out of the holder with a below the lens set is a piece of cake with almost no risk of disturbing the enlarger during the printing operation

    Swapping filters mid print allows me to burn in different parts of the print as separate grades

    It is highly unlikely the filters in your colour head have faded but the MG Filters do slowly fade over time, I am just about to replace mine after 12 years of service.

    I noticed the grades were not evenly spaced any more

    Good luck

    Martin

  5. #5
    RH Designs's Avatar
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    I use a C7700 and recently obtained some Ilford below-lens filters. Grade 5 with these is significantly harder than the maximum magenta filtration available with the built-in filters. I wouldn't recommend the above-lens Ilford filters, changing them would be very fiddly. The below-lens ones are so thin and so far outside the plane of focus that they have no visible effect on image quality, and as Martin says they are quick and easy to change.
    Regards,
    Richard.

    RH Designs - My Photography

  6. #6
    ic-racer's Avatar
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    If you have a step wedge you can test your maximum magenta and see how many grays you get.

    It looks like Mike Sparks of fPoint has only made one post to APUG, but this was it (with respect to fading dichroic filters):

    I'd like to put the question to rest about dichroic filters fading. When my company Focal Point was in it's hay days we rebuilt literally hundreds of color heads each year. Believe me Dichroic filters fade. This having been said if you aren't a pro lab that uses the enlarger every day at least 8 hours per day, it will take a decade or two to notice any difference in your enlargements....

    Best regards,

    Mike Sparks
    Focal Point

  7. #7
    El Gringo's Avatar
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    Thanks for all the replies, I've ordered a set of the under-the-lens filters, which hopefully will help with some my contrast issues if not I'll have to look into my developing times to see if I can add a bit more contrast that way.
    Rhys

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    El Gringo's Avatar
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    A quick update, my filters came this week and I've just finished printing a test shot on each of the 5 grades. Using the filters on my colour head I think the highest grade I was getting was somewhere in the range of grade 3. There was no way I could get anything like the grade 4 and 5 filters from the set are giving me.
    Rhys

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    Hmmm, interesting, I have an LPL6700 with a colour head. Using published charts for the filtration values, I think I can print to about grade 4.5, which is plenty contrasty enough for me, but I do find that for 'normal' contrast (whatever that is) I need to print at about grade 2.5-3 rather than the more usual grade 2. On the other hand, I did see a comment once that beginners often print at a higher grade then they need (and I'm certainly a beginner). It does of course depend on the film and development, for me, Neopan 1600 in XTOL has to be printed at grade 2 or less, while FP4 needs 3 or higher, but that's just me, my chemistry, my enlarger and my preferences....

  10. #10
    hoffy's Avatar
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    Sorry for digging this back up again. I would like to try Ilford Filtration with my LPL7700 and was given a Ilford above lens kit. Did anyone try putting the filters between the neg carrier and the box? Like above, I have a feeling I am not getting the right grades either.

    Cheers

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