Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,548   Posts: 1,544,559   Online: 1024
      
Page 2 of 3 FirstFirst 123 LastLast
Results 11 to 20 of 22
  1. #11
    Athiril's Avatar
    Join Date
    Feb 2009
    Location
    Melbourne, Vic, Australia
    Shooter
    Medium Format
    Posts
    2,532
    Images
    28
    Quote Originally Posted by Photo Engineer View Post
    There are reports here of the single part blix being the lowest quality, and the two part blix being acceptable to the users. No one here (AFAIK) has done a side by side comparison. I have! All film blixes commercially available have some degree of the "bleach bypass" syndrome. Desaturated color, higher contrast, and grainy pictures.

    You are the only possible judge.

    PE
    I noticed this on the Tetenal kit somewhat a few years back when using it, not so much the desaturation though.

  2. #12

    Join Date
    Apr 2012
    Shooter
    35mm
    Posts
    10
    Quote Originally Posted by Photo Engineer View Post
    There are reports here of the single part blix being the lowest quality, and the two part blix being acceptable to the users. No one here (AFAIK) has done a side by side comparison. I have! All film blixes commercially available have some degree of the "bleach bypass" syndrome. Desaturated color, higher contrast, and grainy pictures.

    You are the only possible judge.

    PE

    Ok, so you have actually 'studied' this and concluded that single part blix is fairly inferior in general, very interesting, thanks for commenting!

  3. #13

    Join Date
    Apr 2012
    Shooter
    35mm
    Posts
    10
    Quote Originally Posted by stefan4u View Post
    Dear futile.

    A Blix is not the best option, if it is fresh and active it will work OK, but leaves a different coloured mask. This is visible, but at most times not a big problem. Adapt filtration and you should get fine prins. The basic problem with the blixes is to keep them stable and active in the needed concentration (Reductive and oxidative components decomposes themselves). So the shelf life is quite short, depending of the desired quality it is more a expensive one way product. Don’t use these monopart chemicals at all.
    In lower concentrations, as needed for processing paper prints, a blix works fine…

    But in my eyes your problem is still focused on the temperature / activity of your developer. You will have at least 2-3 degrees Celsius temperature drop if you develop without sufficient prewarm/prewet. This leads to a quite a noticeable underdevelopment, as you remarked.

    Do some measurements, take a complete drum with reels, fill it with an equivalent amount of temperated water, imitate your normal agitation and measure the temperature in the drum after 1:30 till 2 min. and after 3:15 min. Than you easily can calculate how much the temperature declines, and what your actual average processing temperature is. Don’t be too scared

    Do the same experiment with a prolonged prewarm or a double prewash step, you will see that the temperature drop will be a lot less!
    Than increase your process temp a slightly, maybe to 102 °F and see what you get in a new run.

    Now you will have quite a well approach to the desired temperature, and maybe have to add 10-15 sec to the development time for fine tuning. If you do not over exhaust your developer (1 Litre / 4 Films 135/36 at 100 asa) you / your films should doing fine now.

    My favourite chemicals, will not help you very much, the developer is homebrewed, the bleach is a champion /mydoneg air bleach, fixer is tetenal NQ-3 (both minilab chemicals). Prior homebrewing I had flexicolor (lovely) and tetenal but most times separated bleach and fix stages, it is simply a lot cheaper (and better) in the long run.

    Regards
    Stefan


    I'm totally going to do that, using water I will figure how much temperature drop would happen if I don't pre-wash, I'm very curious myself. I told you, last night when I seriously thought about it, it sounded so stupid! A tank, with 2 or even 3 rolls of film inside, all at room temperature, and you pour a 38degree liquid in there, and leave it for than 3 minutes, and you agitate aggressively and everything, OF COURSE that liquid is gonna lose a few degrees by the time the process is done!


    Anyways


    Thanks again,


    Reza

  4. #14
    hrst's Avatar
    Join Date
    May 2007
    Location
    Finland
    Shooter
    Multi Format
    Posts
    1,300
    Images
    1
    What, you don't have a tempered water bath?

    It's usually done so that you have a large tub of water where you hold your tank and chemicals. You use a precision controller heater on the tub, or if you don't have one, you just measure the temperature every 2-3 minutes and add a bit of hot water when needed. Well, with C-41, a large tub alone stays constant for 3'15, but for E6, you need to add hot water to keep the temperature up.

    Well, you can do without a water bath too to an acceptable level, but you have to experiment first. You just need to measure the temperature at the beginning and at the end of the process to calculate average temperature, and adjust your starting temperature until you get an average of 38 deg C. It depends on tank brand and size, room temperature and your agitation style, this is why you have to test it first with water. It might be that 39 deg C works, and of course with two cycles of 39 deg C prewash. IIRC, I once measured 2 deg C temperature drop (from 39.0 to 37.0) with a two-film Jobo tank at room temperature of 23 for 3'15 process time.

  5. #15

    Join Date
    Apr 2012
    Shooter
    35mm
    Posts
    10
    Quote Originally Posted by hrst View Post
    What, you don't have a tempered water bath?

    It's usually done so that you have a large tub of water where you hold your tank and chemicals. You use a precision controller heater on the tub, or if you don't have one, you just measure the temperature every 2-3 minutes and add a bit of hot water when needed. Well, with C-41, a large tub alone stays constant for 3'15, but for E6, you need to add hot water to keep the temperature up.

    Well, you can do without a water bath too to an acceptable level, but you have to experiment first. You just need to measure the temperature at the beginning and at the end of the process to calculate average temperature, and adjust your starting temperature until you get an average of 38 deg C. It depends on tank brand and size, room temperature and your agitation style, this is why you have to test it first with water. It might be that 39 deg C works, and of course with two cycles of 39 deg C prewash. IIRC, I once measured 2 deg C temperature drop (from 39.0 to 37.0) with a two-film Jobo tank at room temperature of 23 for 3'15 process time.

    I will do it today and post an update here, I myself am very curious about the size of the temperature drop...


    About the tub, well, intuitively, I believe if I do that pre-washing carefully so that everything is at let's say 38.3, I don't think the developer would lose temperature (during the process) beyond the 'optimal' range, I will test it anyway though

  6. #16
    Athiril's Avatar
    Join Date
    Feb 2009
    Location
    Melbourne, Vic, Australia
    Shooter
    Medium Format
    Posts
    2,532
    Images
    28
    If your ambient isn't extremely low. A plastic tank does very well. Due to heat insulation, once the film and tank itself is at processing temp via presoak.

  7. #17
    hrst's Avatar
    Join Date
    May 2007
    Location
    Finland
    Shooter
    Multi Format
    Posts
    1,300
    Images
    1
    It WILL drop below the limit, unless you are in a very hot room! As said above, it dropped by 2 deg C when I tested (causing an average error of 1 deg C). Much more than the standard margin of 0.15 deg C, and enough to cause clearly visible problems when not taken into account. The agitation causes more heat transfer through the plastic. Plastic tank is not a proper heat insulator. It has a large surface area.

    But this is not a real problem as you can compensate this by using higher starting point. This is probably the easiest way to do C-41, and while not perfectly repeatable, it can be very close to a good process.

    If your room temperature varies a lot, you need to repeat the test for different room temperatures. I would say it is quite different for 20 deg C than for 28 deg C!

  8. #18

    Join Date
    Apr 2012
    Shooter
    35mm
    Posts
    10
    Alright, this is the situation:


    I used the following:

    - One Paterson Super System 4 tank
    - 3 reels
    - No film on the reels
    - 1 liter of liquid (water)


    Two cases:

    1. No pre-wash. So my tank and reels are cold, actually at room temperature, which was 19.
    2. Pre-washed, for one minute, with 37.8-degree water


    For both cases, I pour 1 liter of 37.8-degree water, and I treat it as "developer", I agitate and everything, after 3.15 minutes I pour the water (developer!) out and measure the temperature.



    The temperature drop is massive, and surprising enough, it is massive for both cases! When I pre-washed, the drop was smaller but still dramatic.

    no-pre-wash case temperature: 34.9 ---> drop of 2.9 degrees

    pre-wash case temperature: 35.4 ---> drop of 2.4 degrees



    and don't forget that there was no film even. I didn't expect it honestly, especially for the second one WITH prewash. The difference is only half a degree!

    It seems that agitation makes the liquid lose its temperature pretty quickly, and having it pre-soaked (pre-washed) does not seem to be that helpful.




    What do you think? Do these numbers (or one of them) surprise you, or did you expect to see more or less the same thing as this? Please, I'd love to discuss this...




    PS. Well, in terms of possible errors/mistakes... I cannot say that I did it flawlessly, but it was a decent experiment, I don't think there are huge deceiving errors here.

  9. #19

    Join Date
    Apr 2012
    Shooter
    35mm
    Posts
    10
    Quote Originally Posted by hrst View Post
    It WILL drop below the limit, unless you are in a very hot room! As said above, it dropped by 2 deg C when I tested (causing an average error of 1 deg C). Much more than the standard margin of 0.15 deg C, and enough to cause clearly visible problems when not taken into account. The agitation causes more heat transfer through the plastic. Plastic tank is not a proper heat insulator. It has a large surface area.

    But this is not a real problem as you can compensate this by using higher starting point. This is probably the easiest way to do C-41, and while not perfectly repeatable, it can be very close to a good process.

    If your room temperature varies a lot, you need to repeat the test for different room temperatures. I would say it is quite different for 20 deg C than for 28 deg C!


    My experiment totally supports your point, yes, it does drop, and WAY beyond the 'optimal' range! You're right!

  10. #20
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    23,025
    Images
    65
    This type of test has been run and reported by others on APUG. This is exactly why it is recommended that you use at least 2 prewet steps of 100F water to temper your "system" before starting development.

    PE

Page 2 of 3 FirstFirst 123 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin