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  1. #1

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    Exposure time and temperature...

    Hi all,
    I am wondering if air temperature has anything to do with exposure time. I shot a couple roll of Ilford Pan F a few years back in -25C (-13F) condition and they all came back with lots of grain. I am wondering IF it was because they were all underexposed and that the lab (which cannot confirm with me) pushed it in the processing and left me with very grainy Pan F prints.
    I asked this because intuitively, chemical reaction time usually is affected by temperature and if the film is cold, would it then slow down the reaction time and affect the light meter reading?
    Cheuwi

  2. #2
    Mike Wilde's Avatar
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    What kind of camera were you using? At low temperature a suspect issue is the shutter may have been slow to open if it was a mechanical shutter, and hence the film could be subject to under exposure; it could also run slow and give you over exposure.

    Extreme cold could also have affected the voltage that the battery powering the metering was productiing, and hence may have over exposed all frames, which would have guven rise to problems, but not nesessariliy grain.

    -25C here also usually means snow. If an automatic metered camera is not 'corrected' it will usally treat the white scene to try to expose it to make it grey. The film does not get enough exposure to yield enough density in the negative to give convincing whites in the print with normal development. To compensate there may have been over development to try to build density in the areas that yielded print highlights.

    There is no chemical reaction on exposure. It is a gathering of electrons on the silver halides.

    How big are the prints; Pan F is pretty fine grained usually.

    You say they all came back grainy; a lot of labs have not a clue what to do with conventional b&w processing. You imply by pushing that they may have looked at one film, the first, and then over developed the rest.

    Usually when the weather around here is -25C the sky is not too cloud covered, and the scenes are of a rather high contrast. Pan F, and most slow films are not known to handle wide dynamic range scenes very well.

    Lots of issues batted around here. Respond as you see fit.
    my real name, imagine that.

  3. #3

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    Thanks Mike for clearing up a few things for me. Based on your comments, I believe the lab was the issue.
    Seeing that you are from the GTA area as well, which lab do you go to? Or do you process your own?

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    All things being equal and if your equipment functions normally, extreme cold increases the sensitivity of film, sometimes dramatically. In Astrophotography with film, a cold back was essential for long exposures with film to reduce sky illumination sometimes referred to as fog and to decrease reciprocity effects during long exposures. Cooling is also used in CCD Astrophotography for many of the same reasons but primarily to reduce "noise" in the exposure.
    Denise Libby

  5. #5
    Sirius Glass's Avatar
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    Quote Originally Posted by archer View Post
    All things being equal and if your equipment functions normally, extreme cold increases the sensitivity of film, sometimes dramatically. In Astrophotography with film, a cold back was essential for long exposures with film to reduce sky illumination sometimes referred to as fog and to decrease reciprocity effects during long exposures. Cooling is also used in CCD Astrophotography for many of the same reasons but primarily to reduce "noise" in the exposure.
    Denise Libby
    So Denise, this is more than a shot in the dark, right?

    Steve
    Warning!! Handling a Hasselblad can be harmful to your financial well being!

    Nothing beats a great piece of glass!

    I leave the digital work for the urologists and proctologists.

  6. #6
    Mike Wilde's Avatar
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    Quote Originally Posted by cheuwi View Post
    Thanks Mike for clearing up a few things for me. Based on your comments, I believe the lab was the issue.
    Seeing that you are from the GTA area as well, which lab do you go to? Or do you process your own?
    I process all my own stuff. B&W, C-41, RA-4 and E-6. Yes, I know I am a bit obsessed with doing it myself.

    One of my other photo related hobbies is to gather bits of old darkroom gear at garage sales and incredibly chaep local esates sales and craigslitings and the like, and assemble complete B&W darkroom kits to be given to those who are interested in this craft to get them started doing their own darkroom work. Necessary equipment, information books, a starter supply of paper, and chemisty, heck an older camera and film thrown in if need be.

    I have set up three individuals this way in the past three years.

    I presently have enough stuff in the basement to make you number 4 if you are interested. This offer has been made to another person about three weeks ago, and so far no call back from him, so it can be yours if you are interested.

    Mike.
    my real name, imagine that.

  7. #7

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    Hi Mike,
    Your offer does sound very attractive... what kind of set up do I need in order to set up a darkroom at home. I need to make sure the wife is cool with it if I need to occupy a room in the basement.
    Do I need running water? My basement, unfortunately, does not have a sink... do I need a sink?
    Winston

  8. #8
    Mike Wilde's Avatar
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    Winston - I have worked though about 9 different living places with darkrooms of one sort or other in all.

    One apartment had the darkroom in a half bath, with shelves that fit onto rails attached to the walls either side of the toilet. You printed on the enlarger on the highest shelf, and then slipped the print down a shelf to the developer tray, sideways to the stop, down a shelf to the fixer, over to the hold bath, etc. The hold bath would be filled with fresh water from an attachement that fit over the sink faucet to do final wash at the end of a session and here the waste water was funnelled down into the toilet.

    You don't need running water; a floor drain is nice to save carrying buckets of used solutions and hold water back upstairs though. If you lug water in, it is always possible to install a small pump to pump it out and down a drain when you get tired of lugging the waste water out.

    I have also set up in two different bathrooms (this was pre-kids, but were in 1 bathroom 2 bedroom apartments), with a dark out blind that popped into the window (one had a vent fan and the outside window was left open a crack). A pile of towels filled the light gap under the bottom of the door. The enlarger rolled in on an old microwave cart, and was rolled into a closet in the spare bed room. The lower cabinet of the cart stored trays, stock solutions, etc. I put a plywood shelf covered in mac-tac over the bathtub for a working surface. The safe light attached to a clip on the side of the back shelf of the microwave cart and was bouced off the celing to light the room. A couple of nails either side of the door frame allowed the extension cord to get up off the floor for the occasion when my mate would call to come in and use the room for the purpose it was intended.

    No darkroom, particularly your first one needs to be perfect.

    Start out loading film into a daylight tank (in a truly fully dark closet at night for darkroom-less places), and there is nothing to keep you from doing the processing of the film in the kitchen and then hang the film to dry in the bathroom shower (usually the least dusty place in most houses).

    Then move to printing in a room in the basement, or wherever where you get in the habit of carrying a 5L or pail of water in each session to allow you to mix up fresh print developer. A 8x10 tray takes about 1L to easily work with it. Stop bath can be re-used, and fixer is generally always re-used. Then use a holding bath for prints after they are fixed. You can take the holding bath/pail upstairs and wash finished prints in the kitchen sink or bath tub, etc, at the end of the session.

    If you have never done this before, we can try to link up schedules, and I will run you though processing a flim, and printing some negatives that have already been processed and are ready to print. I will do this on top of the washing machine and dryer if it takes place at my end to show you that a perfect darkroom is not necessary to get you started.

    I'm out near Erin Mills and Dundas in s/w Mississauga. I can work out a delivery time if you don't have easy access to a car Give me a call (905) 823-2805. I am home most night after 6. .

    Mike.
    my real name, imagine that.

  9. #9

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    Thanks for the info and the offer. I am currently checking out the options around the house for a location - the wife is thinking that it may be a good opportunity to put a bathroom in the basement... $$$.
    What I may do is come out (if you don't mind) and watch you do it once and then decide.

  10. #10

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    Mike, you are doing a great thing helping people the way you do. I got involved with digital years ago but it didnt take long for me to really miss the darkroom. Its very meditative. So I got an rb67 and couldnt be happier. Don Weed

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