Green light and inspection

Discussion in 'Enlarging' started by norm123, Feb 6, 2014.

  1. norm123

    norm123 Member

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    Hi

    I want to try to devellop sheets films by inspection, mostly 4 x 5 and some 11 x 14 films.

    I can't find what to buy to do inspection. Is there a specific item I can use for it?

    How do you inspect your films during devellopment?

    Thank you
     
  2. Shawn Dougherty

    Shawn Dougherty Member

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  3. ww12345

    ww12345 Member

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    You have to make sure your films can be inspected under a safelight (I would say 90% of films today cannot). I'm sure others will correct me if I'm wrong, but it's my understanding that only ortho film can be inspected during development.
     
  4. snapguy

    snapguy Member

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    1950s

    I have not done it since the 1950s, but I used a weak green bulb which I kept a few feet away from the film. The idea is you half-develop the film (or, what you think is proper amount of time for half development) and then take the film out of the "soup" and look at it briefly. It will look muddy, like film that has not been fixed properly. The idea is to look for the dark areas in the film, the developed areas. It is a steep learning curve and you have to practice. But you will finally learn how much more development is needed. Or perhaps that you have to stop the development at once, that you have developed it sufficiently already. Or, you may decide you need to put it back in for several minutes or even switch to a more powerful developer because it is very underdeveloped. Good luck. I am putting together a FrankenGraphic (from spare parts) and will hopefully be shooting 4x5 soon, again.
     
  5. Shawn Dougherty

    Shawn Dougherty Member

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    You can definitely develop most of today's film by inspection using a safelight so long as you follow the proper procedures.

    I have heard some say that it is difficult see TMax 400, I have heard other's say it's no problem as long as you pre-soak and remove the dye... I have not tried it with this specific film.
     
  6. Thomas Bertilsson

    Thomas Bertilsson Subscriber

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    This is not correct.

    The common thing to do is to use a very weak light of green color, and only for a very short period of time. Green is the color that the human eye is most sensitive to, which is the reason for using it.
    A standard safelight is used, with a weak bulb, and you inspect the film from about 3-4 feet distance for a few seconds.
    This does technically fog the film, but not enough to make a practical difference.

    After much practice you learn what the film should look like, and you learn to gauge how much more development a negative needs before you pull it and put it in the stop bath.

    Films like TMax 100 are difficult to gauge, because of the incorporated dyes that are used for sensitizing as well as filtering.
     
  7. norm123

    norm123 Member

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    Thank you everybody for tips
     
  8. richard ide

    richard ide Member

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    Kodak safelight filters for panchromatic materials are either a #3 or a #7B. Both these filters are dark green.
     
  9. Gerald C Koch

    Gerald C Koch Member

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    I would like to add that not only is the eye most sensitive to green light but that many films have a dip in sensitivity in this region. Even so it is very important not to expose the film to the light until development is at least 50% completed. The self masking of the developed silver is an added safety factor.

    The film should be inspected from the base side and not from the emulsion side. This technique takes a bit of experience to do well. The standard time/temperature method is actually more accurate in most circumstances.

    A film can also be put in a pre-bath containing certain dyes to decrease the sensitivity of thee film allowing the use of a much brighter light.
     
  10. Jim Noel

    Jim Noel Member

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    OK, I will correct you. I don't know of a current film which can not be inspected if done correctly. I develop most of my 8x10 and 7x17 films by inspection.
    For orthochromatic films I use a 7 1/2 wat red bulb 5 feet from the tray and leave it on continuously.
    For panchromatic films I use a 7 1/2 watt dark green bulb made for the purpose 5 feet from the tray. Inspections are short, on the order of 2-3 seconds. The first inspection is after the film has developed for 60-65% of the estimated time. It usually takes no more than 3 inspections to get the film where I want it.
    Looking at the emulsion will give false information and the film will be under-developed. The base side must be inspected and one looks first for the highlights.
    Begin by turning off the light for at least 5 minutes prior to beginning development. If this is done, the dim green light will look like a floodlight.
     
  11. rmann

    rmann Subscriber

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    You could also invest in a set of IR goggles - that way you can watch the entire development process. They will also come in handy for loading and unloading film holders.
     
  12. cliveh

    cliveh Subscriber

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    This is all correct and I would like to add that before and during the initial development with the panchromatic film covered in total darkness, you let your eyes adjust for about 20 minutes to this very dark green light before inspection.
     
  13. Gerald C Koch

    Gerald C Koch Member

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    Yes, good point it is very important that one's eyes become adapted to the dark before starting. The light from the safelight is very dim.
     
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  15. cliveh

    cliveh Subscriber

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    Actually Gerald, one point I would dispute in your post is inspection from the base side. I understand the reason behind this, but does this give you enough information to judge development? I would suggest a brief inspection of the emulsion side may be a better option.
     
  16. ww12345

    ww12345 Member

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    Ah, I stand corrected. I knew somebody with more know how would step in and correct me if I was wrong... :smile:

    Very cool about inspection via safelight! I had no idea!
     
  17. Mainecoonmaniac

    Mainecoonmaniac Subscriber

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    I shoot Fuji HRT green sensitive x-ray, orthochromatic film and I process it under a red safelight. I still haven't mastered it. For me, time and temperature has works for me.
     
  18. richard ide

    richard ide Member

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    I learned the hard way that examining the emulsion side and terminating development will give you thin negatives. Possibly with thin tabular grain emulsions the difference would be less.
     
  19. Bill Burk

    Bill Burk Subscriber

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    Haaa, You are right - thin negatives. No there's no difference between types of films. I develop by infrared viewer and the emulsion comes up quickly and you are so right that if you don't flip it over and look at the base, you will be tempted to pull the film. TMY-2 is no different than any other film (though X-Ray film may be a different story - isn't it 2-sided emulsion?)

    (I develop to time and temperature, but with the aid of infrared viewer because it's as much fun as developing prints when you can watch it develop.)
     
  20. Bill Burk

    Bill Burk Subscriber

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    I think part of the reason develop by inspection by dim green light late in the process "works" is... Yes you are exposing the film a little... but you aren't developing it that much longer. So the grains you exposed "to the point of being developable" with the green light, aren't developed for very long.
     
  21. michael_r

    michael_r Subscriber

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    Bill, also note depending on the film and developer formula, the development process itself has a desensitizing effect. This helps with DBI too.
     
  22. Shawn Dougherty

    Shawn Dougherty Member

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    My understanding is that the film is desensitized to a degree by the development. Your idea is interesting though, Bill. Have you read about this anywhere?
     
  23. Gerald C Koch

    Gerald C Koch Member

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    The problem with evaluating the negative based on the emulsion side is that you are seeing reflected light only. So you are seeing only the surface of the emulsion, the rest of the emulsion may be undeveloped. Stopping development at this point will lead to thin negatives. This is why the base side is used since if you see a satisfactory image it means that the entire emulsion has been developed. Thus the warning to inspect the base side of the film. Every discussion of the technique that I have read always mentions doing this.

    The idea that the oxidation products of the developer act as a desensitizer is very old. If the effect ever existed it would be dependent on the developing agent(s) used. I seriously doubt that the developing agents used now would have the same effect. The oxidation products of phenolic developing agents like pyrogallol are vastly different from those of a developer like Xtol.
     
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  24. Shawn Dougherty

    Shawn Dougherty Member

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    So do you have any thoughts about how it does work, Gerald? Developed silver helping to block light? The exposure occuring late in the process so not enough time to develop as Bill suggested? Simply too little exposure to make a difference beyond a slight increase in base fog? All of the above?

    I'm just curious. Thanks!
    Shawn
     
  25. Thomas Bertilsson

    Thomas Bertilsson Subscriber

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    The article linked to by yourself earlier in the thread was to Michael and Paula's web site, and if I remember correctly they use ABC pyro, which is a pyrogallol developer. I wonder if it makes any difference that it's pyro and a rather heavily staining formula?
     
  26. Shawn Dougherty

    Shawn Dougherty Member

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    That's right, they do use ABC pyro. I watched Paula develop film this way and I've dabbled in it myself. Never noticed any fogging that seemed different than what I'm used to... by eye anyway. I've never measured it with a densitometer. My understanding is that there is only a SLIGHT increase if done properly.

    I'm just curious about what is actually happening. I would LOVE to get some nice IR googles, glass trays with an IR light source underneath them some day. :cool: