Philips PCS 2000 alignment and split grade printing

Discussion in 'Enlarging' started by hoojammyflip, Aug 6, 2012.

  1. hoojammyflip

    hoojammyflip Subscriber

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    Hi, I am using a PCS2000, and my toddler has yanked the head so that its drooping a little. Placing a bubble level on it, the bubble slips from middle, but still sits roughly in the centre of the chamber, whereas its perfectly centred on the base board. Things straighten up a bit when I lock the head off. I am wondering, whats the tolerance for alignment? Its obviously got some "tolerance", of the order of degrees, so that its the same whatever the enlargement, logically. I guess, having seen in a Zeiss MTF document some flatness of field discussions that this tolerance is actually very small, but its a cosine relationship, so initially the fall off in performance is slight and then accelerates. I dont want to replace the PCS2000, as its one of two, and I am getting to understand the filtration adjuster now. Has anyone shimmed the base column on one of these...what material would you use, or, given its aluminium....could you file it down/machine it! At least the photo is sharp in the centre.

    Separately, I am looking at split grade printing, and last night was mucking around with 4s intervals. This left me with 16 different exposures on one 5x7 print. But the 4s steps seem too granular, so exposure steps are too high, although I do get a rough idea of which mix of blue and green I want. I was printing with Kodak -ve filtration of 10 blue or 10 green (half power basically). It strikes me when I wind the filtration right up to turn either the blue or green light "off" there is still light coming through the blue and green channels, which means I am not getting pure blue or pure green. If I use higher filtration, it wont really be either blue or green light coming through (I am aiming at mixing 0 and 5 grades). I dont think I could do with less than 5s intervals. Maybe I start using f11/f16 on the lens for fine tuning the mix of blue and green, and then just reduce the final exposure by a factor of 4, when stepping back to f5.6/f8. Anyone have practical experience to share with the PCS2000 and split grade printing please?
     
  2. MartinP

    MartinP Member

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    The Philips enlargers used additive filtration didn't they? The opposite measurements to most other colour-heads so far as I recall. Few others will have tried split-grade printing with Philips, but I can recommend white-light and under-lens filtration with the standard Ilford under-lens filter set.
     
  3. MattKing

    MattKing Subscriber

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    Anyone using a later edition Ilford Multigrade 500 heads will be used to using blue and green light for split grade printing, and I think they have been quite effective :smile:.

    And as for intervals, have you considered using logarithmic (e.g. 2, 2.8, 4, 5.6, 8, 11) instead of arithmetic ones (5, 10, 15, 20, 25, etc.)
     
  4. MartinP

    MartinP Member

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    I thought the Multigrade heads were automatic though? No manual calculations required, just a twist of the knob to change contrast and balance the exposure-time compensation for the different filtration?
     
  5. MattKing

    MattKing Subscriber

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    They are automatic, if you are printing using the paper they are calibrated to, and the tone you wish to match (as contrast is varied) is the tone that was used for calibration.

    I actually use a Multigrade 400 head in my darkroom - it uses magenta and green (EDIT: actually yellow of course) filtration, but otherwise works similarly to the newer 500 series heads. In my experience, the "automatic" feature is helpful, but not perfect - it gets you close.
     
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  6. MartinP

    MartinP Member

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    I remained a little bit curious, so I Googled and an old thread here came up.....

    http://www.apug.org/forums/forum41/34570-philips-pcs-2000-a.html

    So far as alignment goes, using a grain-magnifier you can see there is not much tolerance of mis-alignment as the distance to the easel increases. A normal spirit-level (potentially better than 0,5 degree) is marginal for alignment due to difficulty getting it on to the head, lens-mount and neg-stage and it might be better to use mirrors, or a test-neg and a corner focus-magnifier - or one of the laser alignment tools. Most good-quality enlargers have specific adjustment devices built in for micro alignment, but whether that is enough to combat toddler-assault is another question.
     
  7. hoojammyflip

    hoojammyflip Subscriber

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    Separately, someone has advised me on the depth of field considerations, based upon circles of confusion. If the depth of field allowed for the given circle of confusion limit at the negative side of an enlarging lens is the same as in a camera, its going to be of the order of 0.3mm. When enlarging by a factor of 5x, this leads to a depth of field allowed on the base board of 1.5cm. By my maths, that means 7degrees for the short side of a 5x7, or 5degrees on the long side.

    I looked into some advice yesterday regarding split grade printing on Les McLeans website, and it had some great tips, making it seem trivially simple. Separately, I have a EM 10 winging its way in the post.
     
  8. markjan1

    markjan1 Member

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    We have an Ilford Multigrade 500 Enlarger and Control System with green and blue lamps. Does anyone have information on how to use programs 0 - 9 which are in the switch at the back of the control unit/keypad?
     
  9. MattKing

    MattKing Subscriber

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    Welcome to APUG!

    I would gently suggest that your query deserves a thread of its own - except it already has one!

    See it here: http://www.apug.org/forums/forum43/93644-ilford-multigrade-500-system.html

    Hope this helps, and that you enjoy your time here.
     
  10. hoojammyflip

    hoojammyflip Subscriber

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    I think my maths are wrong on the depth of field stuff. But just looking at a 50 lens depth of field calculator, and given an enlargement distance of about 40cm, you do indeed have roughly 1.5cm in front and behind the focal plane to play with. This then doubles the angles I was talking about. So...your enlarger would have to be pretty badly out of whack for this to be a problem. Of course, any misalignment does introduce a technical reduction in contrast, and the circle of confusion limits are really when the MTF drops to 10%, which is pretty dire, so backing this angle limit off 50% would give a 50% MTF etc. Just print and be done with it I guess! Prints are coming out fine, so its not really a problem.

    Regarding my problem with 4s steps, there is lamp cool down and warm up at these times...anyone using a PCS 2000 should try to avoid sub 10s exposures I reckon. Just backing the lens off to f11 or f16 obviously extends the time. The problem with dropping the green channel back, for example, is that this alters the contrast, as its not possible to entirely shut down either blue or green, without physically putting a green filter at the end of the lens. Some light comes through, even when the channels are switched right down.

    A Stouffer step wedge has just come through which ought to assist in working out what contrast range I can get in the limit, full green, or full blue, and I can work from there.
     
  11. MartinP

    MartinP Member

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    I'd suggest using a card to block the light at short test-strip like times (and use the f-stop system), I thought this was standard-practice, and also please consider the under lens Multigrade filters to simplify so much of the struggle you are going to meet printing in a different way to almost everyone else.
     
  12. Ronald Moravec

    Ronald Moravec Member

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    There is no tolerance period. It must be perfect. This is the last step in the chain so why blow it now?

    Mine was off 5 deg right out of the box. There are clips on the back side of the head so you loosen them and reposition.