Please explain Ilford multigrade filters to me.

Discussion in 'B&W: Film, Paper, Chemistry' started by edcculus, Dec 10, 2012.

  1. edcculus

    edcculus Member

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    I know this is a really basic and almost stupid question. Can anyone help explain multigrade, specifically Ilford filters to me?

    I'm printing on a Beseler 23CIII-XL enlarger with a variable contrast head. This is a link to the head. I'm printing with Ilford MG IV RC Pearl paper at the moment, although I do have some MG Fibre as well. My head has settings for Agfa, Ilford and Kodak papers if IIRC. The Ilford setting goes from green (0) to a dark blue/violet (5). The only instructions I found on Ilfords site say to just set it at 2 and go from there. One of the data sheets also explained that the emulsion on MG paper is sensitive to certain spectrums of light, hence why green vs blue light will help vary the contrast. They offer no other explanation on exactly how or in what situations you would need to use the different filter colors.

    If anyone has a link to a basic tutorial I'd really appreciate it. A few hours of searching via google turned up nothing. If anyone can help with a link, or simple explanation of the filters in regard to the specific Ilford paper, I'd really appreciate that too.
     
  2. MartinP

    MartinP Member

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  3. Simon R Galley

    Simon R Galley Subscriber

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    Hi,

    I am actually not sure what you are asking.......probably just me ?!.

    The use of different colours illuminated on the paper via the negative is what changes the contrast of the multigrade* paper from 0 (soft ) to 5 ( hard ) with grade 2 to 2.5 being the normal grade for printing a correctly exposed and processed negative. You do not have to worry, or indeed know anything regarding the actual colour of the filtrations used.

    You dial in the grade and thats the grade the paper will print at.

    Is that what you are asking?

    * all MULTIGRADE type papers, generically known as Variable Contrast papers.

    Simon. ILFORD Photo / HARMAN technology limited :
     
  4. Pfiltz

    Pfiltz Member

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    I'm a newb in the DR, so all I can offer to you is this . . . .

    Don't wash them

    LOL

    Good Luck.
     
  5. Ghostman

    Ghostman Subscriber

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    These are for split grade printing. So for example, you put in the number 2 filter and make your test print or strip to gauge the exposure time. See number 2 as neutral in light or dark contrast. You don't have to do split grade printing and if you have a good negative you can go ahead and print your picture on a grade 2 or any other filter. As the numbers to up so the darker the contrast becomes.

    For example, here is a basic scenario.

    >You make a test strip on Grade 2 and discover your optimal exposure time is 20 seconds.
    >You find that all tones look good and that grade 2 is sufficient so you go ahead and print on grade 2
    >You don't have to use split grade printing on Variable Grade paper, so you could decide on more contrast and use a Grade 3 filter (or vice versa)

    >You make a test strip on Grade 2 and discover your optimal exposure time is 20 seconds.
    >You split the exposure into 2 part of 10 seconds
    >10 seconds with a grade 5 filter and 10 seconds with a grade 0 filter
    >You can use any grade up and down the grade scale depending on what you want

    Split grade comes in handy when doing lots of dodging and burning and controlling area specific contrast.

    I find I need to be careful about split grade (as a newbie in printing) and first check what I can achieve with a good negative and a straight up single grade exposure.

    Split grade is fun though.

    So, use neutral grade 2 to get your exposure time on a test strip, then divide that time up into however much of the two multigrade paper emulsions you want to expose. For a simple exposure, split in half and try the two extremes (grade 5 and grade 0) then decide what would be optimal from there.

    There is no standard, use and do what gives you the effect you want.
     
  6. edcculus

    edcculus Member

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    I did find that PDF. All it tells me is that multigrade filters are available from 00-5 in 1/2 steps, and that the lowest number is the softest contrast.

    Reading back through the bit about the light sensitivity of the emulsion make a good bit more sense now. I think what was confusing me is that it spends more time talking about magenta, yellow and other color filters. When I went to my enlarger, the dial adjusts from green to blue. Reading more carefully, it seems to be talking about using colored filters to filter white light coming from an enlarger with no variable contrast head.

    I just thought they would spend more time talking about filter colors and giving examples of filters seemingly designed specifically for their MG paper...
     
  7. jeffreyg

    jeffreyg Subscriber

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    I use an Aristo VCL 4500 which allows me to dial in a contrast from green to blue/violet as you mention. It also has other settings that can turn off the green or blue or have blue max. It has a separate switch for normal or split printing. If this is the type of light except for the size then: the on/off switch (not the main power switch) in the "on" position will give you blue max -- blue only at maximum brightness; blue/off -- blue only with adjustable brightness control; green/blue -- green and blue combined with blue intensity being fully adjustable (probably the setting you will most prefer); with that switch in the "off" position it will give you blue max. -- blue only at maximum brightness; blue/off -- off only; green/blue -- green only no blue.


    The more blue the more contrast and the more green the less contrast. A setting of 2 would be a starting point. If more overall contrast is needed then increase toward 5 and conversely less contrast toward 0. You can expose different areas at different contrasts for example you could give an overall exposure at 2 but some part could be burned at 4 if that is your desire or you could go the opposite way or hold back and then expose at some other contrast. Try a test print at different contrast settings and you will see the effect.

    I use Ilford MGF and it works fine. I hope this was of some help.

    http://www.jeffreyglasser.com/
     
  8. edcculus

    edcculus Member

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    Ok that makes a good bit more sense! So lets say I'm printing a somewhat low lit picture of a large old house with plants and ivy growing up the side. I want to get a lot of detail from the bricks, ivy, windows etc. I find my optimal exposure is 20 seconds. I could use a higher number filter (more blue) to really burn in the detail without making the subtle transitions in the shadows fill in. I could then come back and finish the rest of the exposure time with a lower number (more green) to help with the subtle detail.

    Or, say I just want a really high contrast print...because thats my "artistic" vision. I can get my basic exposure using a 2, then just dial it up to obtain a higher contrast?
     
  9. Ghostman

    Ghostman Subscriber

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    Xegatly!
     
  10. edcculus

    edcculus Member

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    Awesome! That clears things up a lot.
     
  11. sly

    sly Subscriber

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    Whoops! Sorry to muddy the waters, but ghostcount doesn't yet have a good grasp about MG filters.

    The best way to learn about them is to pick a negative, one you've printed before maybe, and print at each grade. Skip the 1/2 grades, if you want. The higher grades (4, 5) will need more time than the lower ones. The you'll have a good grasp of what the different contrasts are, and how they can be used for your printing.

    Split grade is much more complicated than depicted. If I can print an image at 2, why would I bother to print 10 seconds with 00, and 10 with 5. I have negs that might call for 3 seconds on 00 and 22 on 5, or I might need a lengthy low contrast exposure, and just a few seconds of high contrast. Check out Les McLean, for the low down on split grade.

    http://www.lesmcleanphotography.com/articles.php?page=full&article=21

    I 'd suggest not going there until you are more familiar with the darkroom and straight forward MG printing.
     
    Last edited by a moderator: Dec 10, 2012
  12. MattKing

    MattKing Member

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    Just in case this is where the confusion arises...

    The OP appears (from his comments) to have a light source that approaches variable contrast in a relatively rare way - it emits light in varying amounts of green and blue, and adjustments are done by adding different amounts of green and blue.

    Most of the information around, including information concerning the sets of filters, deals with light sources that are relatively full spectrum, and filters that subtract differing amounts of green and blue light.

    It is important for the OP to think of light as a mixture of red light, green light and blue light. The red light is visible to us, but doesn't affect the paper. If the mixture of the rest of the light has more blue light than green, the print will be higher in contrast. If the mixture of the rest of the light has more green light than blue, the print will be lower in contrast. So what we need to do is adjust the contrast by adjusting the ratio of blue to green in the light.

    So when he/she reads about using yellow filters, he is reading about taking light which includes lots of red, green and blue and subtracting a portion of blue (to increase the relative amount of green, and therefore reduce contrast).

    And when he/she reads about using magenta filters, he is reading about taking light which includes lots of red, green and blue and subtracting a portion of green (to increase the relative amount of blue, and therefore increase contrast).

    The OP's variable contrast head works more directly.
     
  13. jeffreyg

    jeffreyg Subscriber

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    As I described on the previous page my light source works as Matt described. While there may be several different lights the one I have is from Aristo which I believe is no longer made. If he has an Aristo I would think that the controls are similar. It is quite easy and no other filters are necessary.

    http://www.jeffreyglasser.com/
     
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  15. Michael R 1974

    Michael R 1974 Subscriber

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    Jeffrey and Matt are correct this is additive mixing of blue and green light (through dichroic filters) rather than subtractive mixing. The Beseler 45 Universal VC head worked the same way.

    The key for OP to get started is to know that variable contrast papers bascially have two emulsions, a low contrast layer sensitive to green light, and a high contrast layer sensitive to blue light. By varying the proportions of green and blue light reaching the paper you change the contrast. More green relative to blue = lower contrast. More blue relative to green = higher contrast.

    Roughly, if you dial all the way to green you get grade 00 or 0, and all the way to blue/violet would be maximum contrast (anywhere between grade 4 and 5+). A middle setting giving approximately equal amounts of blue and green light would be around grade 2 to 2.5.
     
  16. edcculus

    edcculus Member

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    MattKing is correct. Here is a picture of my head

    besekerci-1351099405-65002.jpg

    You can't see it in the picture, but you slide the bottom slider to the correct paper, then you dial the yellow knob left or right to select the number. The selection is a smooth transition, not a click to each varying filter. The numbers go from 0, .5, 1, 2, 3, 4, 5. In theory, I could choose something between the numbers to have a slightly different mix of blue/green than directly on 5. There is also a lever on the side to enable unfiltered white light to come through.

    Thanks for all the wonderful detailed responses. I guess I was lacking a bit of understanding on exactly what the contrast numbers meant in the first place (regardless of what color the light is). I've never spent much time in the darkroom and don't even have experience with graded papers. I work in the graphic arts industry, so I have a good grasp on additive vs subtractive color theory. I suppose the Ilford manual spends more time explaining that since its much harder to wrap your head around. My head is actually much more intuitive. low number = low contrast, high numer = high contrast : )
     
  17. MattKing

    MattKing Member

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    FYI, the only reason that there is any reference to specific grade numbers is that traditionally paper had a fixed contrast, and was manufactured in several versions (Grade 1, Grade 2, Grade 3, Grade 4 etc.).

    So the numbers on sets of variable contrast filters, and the conversion tables in various publications are there to assist those who learned to assess contrast while working with those fixed grade papers.
     
  18. kevs

    kevs Member

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  19. jeddy-3

    jeddy-3 Subscriber

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    I also have a question about these filters and perhaps I didn't read things correctly. I am very new to printing and have based almost all of my knowledge on David Vestal's The Art of Black and White ENLARGING.
    I don't mean to intrude on the thread at all. Also, I've read the Ilford PDF.

    According to Vestal, VC paper usually=Grade 2 1/4 or 2 1/2 paper with no filter in place.
    Do you folks typically find that the #2 filter prints with the same, a little higher, or a little less contrast than no filter at all, or does it always just depend on the brand of paper? I know I could just run a series of test prints but am curious to anyone's aswer. I can't seem to find an easy answer online.
     
  20. MartinP

    MartinP Member

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    Jeddy-3, the simple answer is 'who cares'. Unless you are printing a huge mural where you need all the light you can get, always use the filters. That has the advantage that you can preserve some notional mid-tone across the grades and exposures, if you use Ilford filters on Ilford paper anyway. Of course, it is unlikely that the most important part of your print will fall on that tone, but it gives you a starting point for making changes in size and contrast.

    The grade numbers do not mean that you 'must' use 'this' grade for 'that' picture. They are an accident of history. Your usual negatives will usually print around the middle of the contrast range for a usual sort of image - after that, what you do is up to what you want to see. In the Enlarging sub-forum there is a sticky-thread by Bob Carnie over his printing methods (Tips from the Darkroom), which you would find interesting I'm sure.

    One exercise that used to be given to most learners was to make a grid of (small, postcard sized) prints of a neg with a full range of tones that prints easily on a mid-grade. Print each grade and vary exposure by, say, 1/2 stops across a range of a couple of stops and arrange the prints on a board so that you have your 'standard' print in the middle. Going horizontally (change in exposure) or vertically (change in contrast) you see an example of the change in exposure or contrast, by whatever units you have used, and can more easily relate what you see on a future print with what you might want to change to get it where you want.
     
    Last edited by a moderator: Feb 19, 2013
  21. pentaxuser

    pentaxuser Subscriber

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    If the OP goes down the route of Ilford filters but reads extensively about the yellow being lower contrastand magenta being higher contrast such as is the case on subtractive dichroic heads using single filtration then when using Ilford filters he shouldn't worry that the range of Ilford filters do not appear to be made that way, i.e. the grade 4, 4.5 and 5 filters are not progressively darker and more magenta which intuitively you might expect them to be.

    So, in short, just ignore the colours on each filter. They work exactly as they should and even if the grade 5 filter appears lighter than say a grade 3 or even 3.5 it will give a higher contrast

    pentaxuser
     
  22. Nicholas Lindan

    Nicholas Lindan Advertiser Advertiser

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    The Darkroom Automation web site has an application note explaining how variable contrast paper works (and sometimes doesn't):

    http://www.darkroomautomation.com/support/appnotevcworkings.pdf

    Contrary to common belief the various emulsions in VC paper all have the same intrinsic contrast. The only difference is that one emulsion has a green sensitizer added to it - it is the same sensitizer used for Orthochromatic (blue-green sensitive) film. This is very old technology, the addition of erythrosine dye to the emulsion to make it orthochromatic was discovered in the late 1800's. Dupont came up with the idea of 2-emulsion VC paper - called Varigam - in the late 30's.

    The reason that a high contrast filter is magenta rather than green is that VC filters also pass red light. The addition of red results in more illumination when you are dodging and burning. Try putting a deep blue filter in the holder and then hold a cardboard dodging card under the lens -- it is very difficult to see just where in the image you are with the card. The original VC filters were green to blue in color, but user's didn't like them, and that's where the change to yellow to magenta filters originated. Color heads also use yellow & magenta, while VC cold light heads are stuck with green and blue.
     
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  23. jeddy-3

    jeddy-3 Subscriber

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    Martin, Thanks for your reply. The exercise sounds like a good idea to me. I did some printing last night and compared a non-filtered print to my #2, #2.5, #3, just to see what would happen. I got very confused as my non-filtered print is drastically different than what I get with a #2 MC filter. Your exercise sounds like just what I need. I'll do this before attempting to print anything else. Now I just need to figure out which of my negatives are "normal" enough to use. :D I think I'll mount the prints on a piece of cardboard to hang in the darkroom for future reference. Thanks a lot.
     
  24. pentaxuser

    pentaxuser Subscriber

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    Just as a matter of interest what could the unfiltered print be compared to grade-wise and what was the paper? If I recall correctly Ilford says that its VC paper unfiltered corresponds to grade 2

    Thanks

    pentaxuser
     
  25. jeddy-3

    jeddy-3 Subscriber

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    I went into the darkroom just now and turned on my enlarger and guess what I noticed? The stupid negative is on Ilford's XP2 (C41)film. The resulting negative isn't black and white, but BROWN and white.:whistling: I feel very silly and you (and anyone else) are welcome to come over and kick me in the ass, as it should have been obvious to me that brown negatives are going to require a different approach. I didn't realize it last night as I'd been under the red lights a long time and I guess I went a little color blind.

    But for reference, the unfiltered print is lower in contrast and very dark. I am using Arista's RC and FB papers, as they seem to need almost identical exposures as each other. I'll look through the forums for how to best print C41 "B+W" negatives but I will also make the test print grid as Martin suggested. I think it will do me a lot of good.
     
  26. pentaxuser

    pentaxuser Subscriber

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    Thanks for the response. If the print is overall very dark then I wouldn't expect the use of filters to correct that. They will increase contrast and that way appear to brighten the highlights compared to the midtones and shadows so yes parts of the print will look brighter but you need to look at overall exposure as well. If a low contrast but "too dark" print has its contrast raised but at an exposure that simply equates to the "too dark "exposure on the low contrast print then it will still be too dark.

    I might be stating what is obvious to you but a sparkling print is a combination of the right exposure for the highlights with a right exposure for the shadows so the details can be seen. I agree the exercise of printing at all the grades is very educational


    pentaxuser