400 to 100

Discussion in 'B&W: Film, Paper, Chemistry' started by Graham.b, Feb 6, 2009.

  1. Graham.b

    Graham.b Member

    Messages:
    197
    Joined:
    Feb 21, 2008
    Location:
    Swindon,,,,,
    Shooter:
    Multi Format
    Morning all.

    I know this has been done just lately. I ran a 400 TX through my Bessa R, 35/2.5. I had a 400 in there and a setting of 100 on the iso. The lens was set to 1 stop over EX. It was in a very bright snow.

    What would be the best time on the chem's, please. It will be done in TMAX 4-1.

    The tanks going on this Saturday morning to 20C unless there are some i dears.

    Regards Graham
     
  2. SamWeiss

    SamWeiss Member

    Messages:
    51
    Joined:
    Sep 11, 2008
    Shooter:
    35mm
    It is not clear by what you mean here "1 stop over EX." What do you mean by "EX"?

    Assuming you mean that you metered off the sunlight snow then added one stop to the exposure recommend by that measurement.

    The commonly recommended procedure (for snow) I've seen is to expose more than 2 stops above the meter reading (say 2.5 stops, but that is just in the neighborhood, and is there need for greater precision?) This will get you white, not grey, snow. Going only 1 stop over the metered reading will give you rather dingy whites. If I meter off of white objects (and plan to not change my development) I will add between 2 and 3 stops.

    However, if you also used an EI of 100 and not 400, you are already set up to go over by 2 stops (compared to using an EI of 400, and developing according to that EI on the manufacturer's charts.)

    My own experience with TX (in D76 1:1) has led me to disregard any concerns of being a little over a theoretically correct exposure (according to the chart) with that film.

    Of course this all begs the question of how well you metered to begin with...
     
    Last edited by a moderator: Feb 6, 2009
  3. Steve Smith

    Steve Smith Member

    Messages:
    9,154
    Joined:
    May 3, 2006
    Location:
    Ryde, Isle o
    Shooter:
    Medium Format
    Ignoring any metering techniques for snow (and assuming they were correct) I would reduce development time by 25% for each stop.

    You over exposed by 2 stops so .75 x .75 = 0.56 Say 0.6 x the recommended development time for ISO 400.




    Steve.