The Doctor is IN...

Discussion in 'Photographic Discussions' started by Hertz van Rental, Jan 26, 2005.

  1. Hertz van Rental

    Hertz van Rental TPF Noob!

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    Things seem a mite slow around here...

    So to pass the time I shall offer my services to anyone that wanders in.
    Just ask me a question about Photography - anything at all - and I shall do my best to answer it.
    This is a serious offer so no levity.
    It can be Technical, Scientific, Historical, Practical, Sociological, Philosophical, Psychological, whatever, just so long as it is a question that has been bugging you and you have been unable to find an answer... or one that you could understand.

    Any takers?
     
  2. oriecat

    oriecat work in progress

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    I'll bite! Other than the obvious answer of "the ph is different" :mrgreen:, can you give me a brief understanding of the differences between using an acid and/or alkaline process in the darkroom?
     
  3. Hertz van Rental

    Hertz van Rental TPF Noob!

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    That's a very broad and rather complicated subject. There are a number of acid and alkaline processes in the darkroom. I presume that you mean 'why are developers alkaline and stop/fix acid'.
    We are talking RedOx reactions here.
    In very crude terms (so there are of course exceptions):
    Alkaline substances 'donate' electrons and acids 'take' electrons.
    In development you are reducing the silver bromide to pure silver around latent image points. The silver ions are positive which means they need an electron to become metalic silver. Making the developer alkaline means that there are electrons available for this. If the developer was acidic then the silver would be turned in to silver salts of the acid and be disolved into solution.
    In stop bath you are stopping development - the acid balances the RedOx potential and development stops (development needs to take place in an alkaline environment so if you neutralise the alkali....).
    In fixing you are removing the unexposed/undeveloped silver bromide. Silver halides (bromide, chloride etc) are nearly insoluble. They need to be converted into soluble salts. Thiosulphate does this very well, forming soluble Silver thiosulphate (cyanide is even more effective but has one or two small drawbacks - cost is one). Fix is usually acidified just to prevent developer carry over which would interfere with the process (the developer tends to develop out the silver that has gone into solution and it coats onto the print as dichroic fog).
    Does this answer your question?
     
  4. oriecat

    oriecat work in progress

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    Thank you :), that does help with some (beginning) understanding of it all. I have seen people who specify that they like to use an all alkaline process, so that's why I was wondering about it the differences.
     
  5. aggiezach

    aggiezach Yup...

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    Yeah I've seen that around as well, and my curiosity engine was running! Thanks for that excellent explanation hertz!

    I'll try to think of some questions on my way to houston today and get back to this thread tonight!

    Zach :D
     
  6. jbnhl

    jbnhl TPF Noob!

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    Hey i have a question... I read in another thread that pretty much you should spend good money on a good lens for your enlarger in order to get good results after spending good money on pre-developing equipment . I understand this, but was wondering if you knew anything about the lens i have. I have a Voss 1:35/50mm lens, and it came with my Bogen 22A. Im new to developing, and so far i think the results are good, but then again, im new and i probobly dont have an idea of good or bad yet. any thoughts would be much appreciated
     
  7. Hertz van Rental

    Hertz van Rental TPF Noob!

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    Voss? Afraid I've never heard of that one. That doesn't mean anything though. Your lens may be a good one but I can find no information on it anywhere. If it was a company making high quality lenses someone would have noticed and brought it to our attention (I am quite prepared for someone who knows to chime in and say they are specialists who produce the finest lenses the world has ever known. It happens and I am always willing to be corrected - but I'm not holding my breath). It is most likely one of the multitude of cheap, average lenses usually bundled with an enlarger.
    When you buy quality hi-fi you get cheap interconnects with them. They work and most people are happy with them. But if you try an expensive high quality interconnect then you suddenly notice the difference. It's the same in Photography.
    But don't go changing things just because. If you are happy with the results you are getting at the moment then stick with it. At a later date you may find the lens has shortcomings - then think about upgrading. But if you don't know if you need a better lens then you don't need a better lens. Spend your money on something else.
    I could also say - and this is no criticism - that until you get good at exposing and processing your films you won't get much benefit from upgrading your lens anyway.
     
  8. jbnhl

    jbnhl TPF Noob!

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    Thanks, before i posted, i tried finding info online but didnt find much. Yeah since im so new to it all, im gonna keep on using it until i feel like it is limiting me or something like that. Darkrooms forever!!!
     

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