Color correcting

Discussion in 'Color: Film, Paper, and Chemistry' started by Ian, Aug 27, 2006.

  1. Ian

    Ian Member

    Messages:
    25
    Joined:
    Nov 2, 2004
    Shooter:
    8x10 Format
    When correcting for color with gel filters, would it be better to use a wratten or cc filter system? At the moment i have not decided, but just wondered what other people have used. It is quite an investment in a filter set, and i want to get it right.
     
  2. Nick Zentena

    Nick Zentena Member

    Messages:
    4,677
    Joined:
    Nov 21, 2004
    Location:
    Italia
    Shooter:
    Multi Format
    In the enlarger? If you're using filters then you want CP. Colour printing filters. I think Freestyle still has a set for sale. Better would be a colour head IMHO.
     
  3. Ian

    Ian Member

    Messages:
    25
    Joined:
    Nov 2, 2004
    Shooter:
    8x10 Format
    Sorry buddy, forgot to mention that these filters are for film exposure.
     
  4. Roger Hicks

    Roger Hicks Member

    Messages:
    4,913
    Joined:
    May 17, 2006
    Location:
    Northern Aqu
    Shooter:
    35mm RF
    I use a mixture. Sorry to be unhelpful!

    Wrattens for gross correction; CC for fine tuning.

    Cheers,

    R.
     
  5. Thomassauerwein

    Thomassauerwein Member

    Messages:
    1,627
    Joined:
    Apr 20, 2003
    Location:
    Southern Cal
    Shooter:
    Large Format
    What Roger said with a couple additions. Whenever possible correct from the light source. Camera corrections I find glass filters the best. Hard to get and expensive plus fragile but worth it from my viewpoint. Especially with grad filters in the landscape.
     
  6. Helen B

    Helen B Member

    Messages:
    1,557
    Joined:
    Jul 1, 2004
    Location:
    Hell's Kitch
    Shooter:
    Multi Format
    The only time I use CC filters is when correcting for fluorescent lights, in which case I use either CC10M or CC20M. Otherwise I use LB (light balancing, Wratten 81 and 82 series) or occasionally conversion (Wratten 80 and 85 series) filters for colour temperature adjustment. CC filters are not good for colour temperature adjustment of continuous-spectrum sources (eg tungsten lamps) because their spectral absorbtion changes too abruptly. My choice of filters reflects my requirements, and people with different requirements would use different filter sets. The choice of negative or reversal film, how accurate you want the colour rendition, how much of the character of the light you want to keep, whether or not it is practical to filter the sources instead - these are all factors that will affect your choice of filters.

    Will you be using the filters with negative or reversal film, and in what conditions (documentary, studio etc)?

    Best,
    Helen
     
  7. Ian

    Ian Member

    Messages:
    25
    Joined:
    Nov 2, 2004
    Shooter:
    8x10 Format

    Thanks Helen.

    I plan to use only Kodak Portra 100T. It would be used in many lighting situations, mostly outside and many subjects. I want to produce the best possible neg without having to correct it later in Photshop prior to printing.

    PS. like the hair by the way.
     
  8. Helen B

    Helen B Member

    Messages:
    1,557
    Joined:
    Jul 1, 2004
    Location:
    Hell's Kitch
    Shooter:
    Multi Format
    Hi Ian,

    If you are using neg film then you need not make the fine adjustments that would be required for reversal film, referring to the filter on the camera lens. Fine adjustments can be made on the overall balance at the printing/scanning stage. Adjustments for different light sources and partial colour casts are another matter, and the magic Photoshop techniques for that are outside APUG. However, the aim is to filter the sources so that they match, or at least so that they give the effect that you want. The movie "Collateral" and almost anything shot by Chris Doyle for Wong Kar-wai always come to mind as great examples of using the qualities of different light sources.

    That issue of consistency aside, restricting the discussion to the filter on the camera:

    The most important filter will be an 85 or 85B to convert daylight to 3200 kelvins. In the Heliopan/B+W/Rollei nomenclature that would be a KR15.

    Light balancing filters will hardly ever be necessary. Portra 100T has quite a bit of overexposure latitude, and that can be used to the same effect as a filter. For example, all an 85 filter does in daylight is to cut down on the light progressively from red to blue, with the most reduction at the blue end of the spectrum and no reduction at the red end. You open up to compensate for the filter.

    If you just open up the same amount, but without the filter, the red-sensitive layer gets about the same amount of exposure as it would if you had opened up with the filter (because the filter doesn't affect the red end of the spectrum) and the blue-sensitive layer gets overexposed (because the blue light hasn't been reduced). But that overexposure doesn't matter with negative film.

    Getting all three layers exposed the same is still a good goal, but it isn't as critical as it is with reversal film, or as it was with negative film in the good old days.

    So, the conclusion of all that is that there is an advantage in using conversion filters (large shifts in colour temperature) but little advantage in using the LB filters for fine tuning. There's no harm using them, of course.

    Apart from the colour temperature or correlated colour temperature, there is also the green-magenta balance which you would normally take care of with a magenta CC filter. For negative film I wouldn't bother with anything other than a CC20M and a bit of overexposure.

    There are combined colour temperature and magenta filters sold by the major manufacturers. You may need such a thing for florries balanced for daylight with remaining green if you are using tungsten-balanced film. I'd have to refresh my memory about those because I don't use them nowadays.

    Including a grey reference, or grey, white and black, in a spare frame helps.

    Were you thinking of using a colour meter?

    I hope all this makes sense. Exactly what the answer is for you will depend on exactly what you want.

    Best,
    Helen
     
  9. Ian

    Ian Member

    Messages:
    25
    Joined:
    Nov 2, 2004
    Shooter:
    8x10 Format
    Hi Helen.

    Thanks for the info, most helpful.

    Yes i have a color meter it's a Gossen i got it of that ebay thing.

    I want to get the neg as close as possible to perfect for my own peace of mind, and you know what they say, if you want something doing properly do it yourself.

    The negs would be drum scanned and stiched in Photoshop (2 x 8x10 = 8x20) and printed via laser light printer. All this is very expensive in the UK compared to the US so you can understand that the less i leave to others the better as i have no control over the processing or scanning.

    I did as this question of Kodak but got no reply so maybe you could help with it. What would be best to use for a test shot, grey card or color card or both? This i would intend to do initially to set up my taking lens, light and color meter with a new batch of film for neg density and color balance. I would have to do further tests i expect as some exposures would run to 20-30 mins.

    Regards

    Ian.