JLA Analog

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    1. perca

      I believe replacing the two metabisulfites is in principle possible. As per Steve Anchell’s Darkroom Cookbook they can be replaced weight for weight.
      I have never tried it though…

  1. Pingback: The Last of Her Line... Praktica MTL50 - JLA Analog

  2. Subhi alghussain Guston

    So does Rollei have RF table that they can provide for different timing over 60 seconds
    Up to 20 minutes???
    I like to shoot day time or around sunset and I use 10 stopper and polarizer and 2 stops and ND filters to get long exposure
    I normally use Fujifilm velvia 50 transparency color slides and I use fujifilm RF time table
    Do you think that Rollei Ortho supper 25 will , react the same as with fujifilm 50 ???

    1. perca

      I have observed that the reciprocity failure is a simple physical process, and as such can be modeled with a reasonable accuracy. The curve will of course be different for different emulsions, but once modeled it is usually accurate (if in doubt, bracket).

      Have a look at the app over here: http://www.jla-analog.net/reciprocity-failure-calculator/ – it is interactive, with default values entered from Ilford datasheets, but user editable. If you replace the defaults with data points from Rollei Ortho or Velvia 50 datasheets it will calculate the curve automatically, and supports saving the data in csv format.

  3. Ramón Menéndez-Manjón Sancho-Miñano

    Mi primera cámara de fotos fue una FLEXARET, que había comprado mi padre en su juventud.
    Hice muchos rollos, en blanco y en negro, en color y diapositivas.
    Los conservo, también los que mi padre nos hacía.
    Yo no tengo esa cámara. Veo que hoy se siguen vendiendo y por Internet he conocido vuestra agrupación.
    Un saludo desde Oviedo, España.

    1. perca

      Hi, and thanks for your kind words!

      The A solution takes a bit of stirring, as it does not dissolve easily. Hot water helps.

      The original recipe asked for 50°C water, I usually don’t measure it too carefully and just pour in some leftover water from my electric kettle.

  4. Many films reasonably follow a characteristic power curve for reciprocity. I keep them in my phone as it is a simple calculation to do on the spot. I rate RPX25 the same as Ilford PanF – after 1 second, the value in seconds to the power of 1.33 is close enough. 10 goes to 21, 20 goes to 54, 50 goes to 181.

    Given you have just three data points from sheet and no indicated basis of calculation, you may have to resort to experiment.

  5. Logan J

    This is awesome. Makes me feel good that you’re able to see through the viewing lens even with a 62mm over the taking lens; I just bought a b36 to 49mm and was worried about this, so I should be fine! I’m excited to try mine out when it comes, I was thinking the same thing as you – some IR photography should be fun!

    1. perca

      Thanks! IR photography with a TLR (or a rangefinder) is fun.
      It would be even more so if I was not forced to use a tripod due to the long exposure times necessary, but one can not have everything…

  6. Gustavo Lemos

    Hey there!

    I appreciate very much the suggestions regarding dilution. Im gonna try lith printing for the 1st time and i intend to use your dilution.

    Id like to ask you about the range of developing times it requires. I understand it may vary a lot, but it would be nice to know how much, minimum, maximum.

    Again, thanks a lot!

    1. perca

      “old brown” is a colloquial term for old developer saved from a previous developing session – very expired, and thus brown in color. It will not work develop by itself anymore, but it does contain some semiquinone and bromide, which will work together with the fresh developer. You will find conflicting opinions about the utility of this – but many (including myself) printer swear by it. If only as a confidence builder…