Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,938   Posts: 1,557,301   Online: 1051
      
Page 3 of 5 FirstFirst 12345 LastLast
Results 21 to 30 of 41
  1. #21
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    23,197
    Images
    65
    Quote Originally Posted by jd callow View Post
    Ron,
    My experience is different, although I haven't made a print in 18 months maybe things have changed and or it may have something to do with the lamp output and not the paper.
    There is a warm up and afterglow associated with some types of lamps, most notably tungsten. This increases the red output of the lamp and makes prints more cyan. The longer the light is on, the more the afterglow as the filament cools down.

    I use halogen lamps.

    PE

  2. #22
    jd callow's Avatar
    Join Date
    Jan 2003
    Location
    Milan
    Shooter
    Multi Format
    Posts
    8,002
    Images
    117
    As do I in my durst, but I'm unsure of what was used in the Beselers and Omega's I've used.

    *

  3. #23

    Join Date
    Feb 2005
    Location
    Fort Collins, CO 80521
    Shooter
    Large Format
    Posts
    178
    Images
    11
    I have eight 250W halogen bulbs in my head. When I first starting printing I was using all three settings liberally like 90Y 50M 30C and very long exposures were the rule. I had no clue about what I was doing. I burnt out all eight bulbs in less then 6 months. Now my settings are more like 10Y 15M 00C, and I adjust the aperture so that my exposure vary between 5 to 10 seconds. I have not burned out a bulb in three years, and I am printing all winter long.

    A lot of things I am noting here are based on memory and observations over long periods of time so the degree of accuracy is questionable. However, I am getting to a place where my sales demand that I can fill orders fast so I need to spend sometime quantifying all of these issues, if indeed, they really exist.

    Recently I got a batch of 20x24 Fuji CA paper paper that significantly deviated from settings I have recorded in my database for my master print. I was very surprised. I do have a JOBO ColorLine 7000 color analyzer that I have never used. It has the ability to create a virtual master (VM) YMC setting, and then I can calibrate each batch of paper with respect to changes from the VM settings. These are called batch adjustment (BA) settings and could be recorded on the applicable box of paper. All settings in my database for the master prints would be VM settings. When I would set up my colorhead for a print, I would first set the VM setting and then add in the adjusts for the BA setting of the paper I am using. I think the JOBO will also compute print density setting using the same model. Of course, this is just another idea I will be playing with.

    Just for the record I would never recommend a color analayzer for fine-art photography. They are designed for rough production lab work, but used in the manner I just outlined above, they may be a very productive tool.

  4. #24
    Mick Fagan's Avatar
    Join Date
    Sep 2005
    Location
    Melbourne Australia
    Shooter
    Multi Format
    Posts
    2,844
    Images
    29
    2,000 watts of lighting, sounds like an 8x10 enlarger.

    I don't know what you call long exposures, but in my book a long exposure is one where you set the timer in minutes, something like 5 or 7 minutes for an exposure. This is for mural enlargements using a 10x10 horizontal enlarger.

    With a conventional vertical enlarger with 2,000 watts of go juice, unless you were enlarging with a 380 or larger lens at f64 or so, I wouldn't expect anything longer than about 25 seconds, 45 seconds tops, for the size of enlargements you are talking about.

    Yes, the lights can go out, when one goes you do have to replace the whole 8 globes.

    I would suggest with your reasonably short exposures for a 2,000 watt head, you may be getting minor colour changes due to lamp temperature fluctuations.

    The best 2,000 watt tungsten head enlargers, always had a shutter in the head. That way the lamps stay on permanently (so to speak) and when you press the button your integral timer trips the shutter and away you go.

    If you place a quite sensitive light meter under your enlarger, place some extra diffusion material above the sensor, then trip your enlarger in total darkness and watch the meter change as the exposure ticks on towards a minute.

    I have the original Jobo Colorstar analyser made by Lici, it has a digital readout and I know that a powerful colour head will still be warming up for the first 5 to 10 seconds. In fact all tungsten lamps do, but with a power source as you have the effect can be noticed by paper more easily, than with a single tungsten lamp enlarger

    Mick.

  5. #25
    Mick Fagan's Avatar
    Join Date
    Sep 2005
    Location
    Melbourne Australia
    Shooter
    Multi Format
    Posts
    2,844
    Images
    29
    I forgot about the afterglow effect of all of those lamps, it is there, and with 8 globes a glowing

    Mick.

  6. #26
    Ian Grant's Avatar
    Join Date
    Aug 2004
    Location
    West Midlands, UK, and Turkey
    Shooter
    Multi Format
    Posts
    16,331
    Images
    148
    A friend runs a pro-lab near where I live in the UK, he spent many years as a Durst engineer and he taught me many years ago that to overcome slight colour shifts at different enlargements adjust the aperture to keep the actual exposure time constant. All his printers were adjusted so that the exposure was constant regardless of the lens used, and they did the same with their LF enlargers.

    Using this constant exposure time method means that any warm up and after glow is constant, and with older papers helped overcome reciprocity too.

    Ian

  7. #27
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    23,197
    Images
    65
    What Ian says is what I also do (or try to do) but sometimes due to magnification I just cannot do it, I have to change exposure time. But, within those limits, color balance is unchanged as is filter pack.

    However, there have been many reports of recent deviation in Fuji CA filter packs. I have to assume this is their new CA II paper which uses new emulsions. It was reported on at the ICIS conference in 2006 here in Rochester. Apparently, the filter pack change is not trivial.

    PE
    Last edited by Photo Engineer; 06-07-2008 at 10:50 AM. Click to view previous post history. Reason: Bad error in phrasing.

  8. #28

    Join Date
    Feb 2005
    Location
    Sydney
    Shooter
    Multi Format
    Posts
    1,364
    Images
    84
    I heard the paper changes were to optimise for digital printing, i.e. lambda & frontier but the paper is now more difficult for optical printing.

  9. #29
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    23,197
    Images
    65
    Quote Originally Posted by goldie View Post
    I heard the paper changes were to optimise for digital printing, i.e. lambda & frontier but the paper is now more difficult for optical printing.
    Not so!

    The changes made it all round better.

    PE

  10. #30

    Join Date
    Jan 2004
    Location
    Cleveland, OH
    Posts
    378
    Even without afterglow, which most people do have to deal with so it will factor in, you're going to run into paper reciprocity.

    A good rule of thumb is to adjust F/stop rather than exposure time, but this will then start to affect sharpness at either extreme of the lens.

    I'd say that you'll run into paper reciprocity shorter than 10 seconds and longer than about 60, it'll be minimal within this range.

    With B&W paper, I've heard you still get about 1/6 stop of reciprocity every time you double exposure. It will be different with color paper, but probably not too different.

    Kodak and Fuji papers have gotten much better than other competitors' (are there any even left?) in terms of minimizing color shift with changing exposure, but IT IS STILL THERE. If anyone would like, I'll post samples. I was using "Ultrafine" paper back in '05, probably rebranded Mitsubishi or Konica or Agfa, and it had very pronounced color shifts with changing times.

    The newer papers have probably been heavily optimized for short exposures; there'll be little to no improvements over a minute, as they're working on optimizing paper for quicker exposure in digital machines, and really couldn't care less about people dodging and burning in the color darkroom. If Kodak cares so much about color darkrooming, then why did they discontinue the 5x7 size?

Page 3 of 5 FirstFirst 12345 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin