Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,549   Posts: 1,544,635   Online: 667
      
Page 10 of 12 FirstFirst ... 456789101112 LastLast
Results 91 to 100 of 118
  1. #91
    David Allen's Avatar
    Join Date
    Nov 2008
    Location
    Berlin
    Shooter
    Med. Format RF
    Posts
    421
    Michael R 1974
    David, the problem is posting a print or a negative tells you very little unless there is something to compare it with. Even then, there are still all the variables involved in getting to the print besides the negative developer. Not to mention the printing preference of the photographer. I don't see any evidence of enhanced shadow or highlight detail in the posted examples vs what could be done with plain old D-76.
    Michael, I agree that without direct comparisons (i.e Here is a scene exposed at X processed in Y and here is the same seen exposed at X and developed in Z) the only things that can be assessed from a posted image are:
    • If it appears to have a full range of tones.
    • How a particular scene is rendered.


    The aim of the posted images were:
    • To demonstrate that BTTB works.
    • To illustrate (through image and words) the exposure used for a given scene and that all tones are printable.


    I am sure the images that I posted could also be achieved with D-76 or any other brew someone likes.

    What, as I have just realised, has not been mentioned so far on this thread is WHY I prefer BTTB. When I used to do large format natural landscapes, I would process in HC110 and adjust development for each individual negative. One of the reasons that I became unhappy with HC110 was that I switched to urban landscapes using medium format. On a given day when I go out to make photographs, I might go through several rolls of film in roughly equivalent light. Other days I might only make a few photographs in varying lighting conditions and then finish the film on another day with completely different lighting conditions. The problem was that, from my previous experience of using HC110, I could adjust the development to compensate for any one of the scenes that I had photographed. What I couldn't do is adjust the processing to suit all of the scenes.

    This is where, after testing, I landed on two-bath developers. Whatever the science, or indeed wild claims made by many advocates that two-bath is perfect for everything, my experience is that by exposing for the level of shadow detail I want and processing for a fixed time in BTTB developer, I achieve 100% printable negatives (success rate of seeing images is another question) without having to bracket, do new tests (unless I change my camera - last time was 13 years ago) or worry that they will be difficult to print / be underexposed / have blown highlights / etc.

    Bests,

    David.
    www.dsallen.de

  2. #92
    baachitraka's Avatar
    Join Date
    Apr 2011
    Location
    Bremen, Germany.
    Shooter
    Multi Format
    Posts
    1,371
    David, is is not giving some sort of expansion and contraction when you shoot at different lighting conditions and process with BTTB.

    I presume we do exactly the same if we test and establish the developments time say for N=7 stops SBR with single-bath developer and see where the rest falls(SBR < 7 or SBR > 7).
    OM-1n: Do I need to own a Leica?
    Rolleicord Va: Humble.
    Holga 120GFN: Amazingly simple yet it produces outstanding negatives to print.

  3. #93
    Rudeofus's Avatar
    Join Date
    Aug 2009
    Shooter
    Medium Format
    Posts
    1,653
    Images
    10
    Michael R.'s curves show that BTTB is a low contrast developer with a more or less straight characteristic curve (yes, I was surprised by that, too). What I don't understand is why David Allen wasn't able to adjust his contrast by choosing different paper gradations. I've done some tests with Foma 312 paper and a 4x5" Stouffer wedge, and the differences in dynamic range with different gradations are surprisingly high.
    Trying to be the best of whatever I am, even if what I am is no good.

  4. #94

    Join Date
    Feb 2010
    Location
    Montreal, Canada
    Shooter
    Multi Format
    Posts
    4,742
    Just remember these are not inherently low contrast developers. It all depends on how much time you give in bath A. You can get whatever contrast you want. Minus, normal, plus, whatever. I just think they offer more with low contrast development than if you use them for normal or increased contrast.

  5. #95
    David Allen's Avatar
    Join Date
    Nov 2008
    Location
    Berlin
    Shooter
    Med. Format RF
    Posts
    421
    Quote Originally Posted by Rudeofus View Post
    Michael R.'s curves show that BTTB is a low contrast developer with a more or less straight characteristic curve (yes, I was surprised by that, too). What I don't understand is why David Allen wasn't able to adjust his contrast by choosing different paper gradations. I've done some tests with Foma 312 paper and a 4x5" Stouffer wedge, and the differences in dynamic range with different gradations are surprisingly high.
    Dear Rudeofus,

    Why would I want to complicate things? BTTB developer is no more a low contrast developer than many others - it is simply a developer that works wonderfully with images exposed over quite a range of subject luminances. Why would I (want to 'improve' things when everything works so well??) want to change things when I get the results that I want?

    I see the options available when printing as being a way of interpreting the definition of how I an image to 'look' and how I want my prints to be seen. In this case, a negative that presents a wide range of opportunities is the 'best' negative for me as (I can reproduce the scene how I want to).

    Bests,

    David.
    www.dsallen.de

  6. #96
    David Allen's Avatar
    Join Date
    Nov 2008
    Location
    Berlin
    Shooter
    Med. Format RF
    Posts
    421
    Michael R.'s curves show that BTTB is a low contrast developer with a more or less straight characteristic curve (yes, I was surprised by that, too).
    Sorry, I do not think so.

    Bests,

    David
    www.dsdallen.de

  7. #97
    Rudeofus's Avatar
    Join Date
    Aug 2009
    Shooter
    Medium Format
    Posts
    1,653
    Images
    10
    Quote Originally Posted by David Allen View Post
    Michael R.'s curves show that BTTB is a low contrast developer with a more or less straight characteristic curve (yes, I was surprised by that, too).
    Sorry, I do not think so.
    Look at his plot here. His plot shows a gamma of (1.8 - 0.4) / (3.9 - 0.9), which is about 0.47. Call it whatever you want, but that's a low contrast developer in my book. Not POTA type low contrast, but lower than normal.
    Trying to be the best of whatever I am, even if what I am is no good.

  8. #98

    Join Date
    May 2007
    Location
    central anatolia, Turkey
    Shooter
    Medium Format
    Posts
    415
    Images
    16
    stoeckler a bath is not thornton's a bath and stoeckler b bath is not thornton's b bath. that is why, all things being equal, thornton's two bath will give you a negative with more contrast than stoeckler's ie Michael's data is not, sensitometrically speaking, applicable.

  9. #99

    Join Date
    Feb 2010
    Location
    Montreal, Canada
    Shooter
    Multi Format
    Posts
    4,742
    Thornton's A bath is not much different than either D-23 or Stoeckler's. But I did try Thornton's at the time for fun. It behaved no differently in terms of curve shape than the other Metol-sulfite + alkali formulas I tried. You also seem to have ignored the tests I ran with metaborate in bath B, which Thornton (incorrectly) said was required instead of borax.

    I will say this one more time. You can't say Thornton's gives x contrast, Stoeckler's gives y contrast, etc. Any of these formulas can give you any contrast you want. You simply adjust the time in bath A. Development occurs in both baths.

  10. #100
    Bill Burk's Avatar
    Join Date
    Feb 2010
    Shooter
    4x5 Format
    Posts
    3,291
    Images
    46
    Michael R 1974,

    At first glance I thought your curves were normal contrast but now I see the x and y scales are scaled a little different. The contrast is a little low as Rudeofus pointed out. But hey, I know you are just showing one example test of one two-bath developer trying a few variations of bath B...

    I agree, you can get any contrast from any developer, and I'm sure there are limitations to that and points to discuss.

    My sister gave me a stack of old reference pocket references last weekend, and in one of them (The Camera Pocket Photo Guide 1942) D-76 is listed as a "low-contrast" developer. I haven't figured out whether that's a typo (the book does contain typos), or whether I should take it as a newly learned "fact" that D-76 is "low contrast"... I never thought of it that way.

    David Allen,

    I appreciate when you name a photographer's style. In the end it is the "Results" of photographers you admire that should guide a choice of developer (if it's relevant, some photographers don't focus much on chemistry). Anyway, I love taking side-trips and learning another photographer. Keep bringing up examples whenever you want to illustrate a point, I enjoy it.

    I believe even though you say you don't follow the curves and sensitometry school of thought, you have a scientific approach... Your description of Minimum Time to Maximum Black is a good example, that's a logical way to get the details you want to catch on film... It sounds like a historic speed determination method... a little like Fred Picker of Zone VI studios, and the Zone System, but tailored to your own style. I support your right to determine film speed your own way, "freedom of speed" is like "freedom of speech" to me...

    Historically there were lots of ways to determine film speed and some of them had a touch of "see what makes the least visible image on the print"... Later sensitometry and curves were used as the basis for standards and we no longer had to have cross-reference charts to the different kinds of speed testing methods. My 1942 book lists "Weston" "General Electric" "H&D" and "American Scheiner" speeds, and calls "High Speed" films "Weston 100" and "GE 150" - I think that describes a film that today would have a box speed of ISO 200.

    And you would shoot it at 100... So would I.

Page 10 of 12 FirstFirst ... 456789101112 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



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