ULF reciprocity quandary

Discussion in 'Color: Film, Paper, and Chemistry' started by Mike A, Mar 21, 2006.

  1. Mike A

    Mike A Member

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    I've recently started shooting some Efke PL25 in 11x14, the lighting conditions I'm shooting in routinely put me in 4, 6 and 8 minute exposer times. Part of the long exposer times I'm experiencing is because of depth of field issues in ULF, I usually have to stop down to f90 or f64 minimum.

    J&C list reciprocity times as follows:
    Efke PL25/50 Suggested Reciprocity Adjustments

    to 1/2 second - 0 stop

    1 second - 1/3 stop

    10 seconds - 2/3 stop

    100 seconds -*1.5 stops

    At a 4 minute exposer I'm already at 240 seconds and going down probably more than three stops (f45) which does not help me.

    I would much rather extend my exposer time than mess with my already small f-stop scale.

    Is there any way to accurately figure out extended reciprocity times from the above tech info provided by J&C?
     
  2. Donald Miller

    Donald Miller Member

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    Exposure is a condition of the time the lens is open and the size of the lens opening. That is true of reciprocity just as much as a normal exposure.

    If you are at four minutes then a one and one half stop adjustment would be ten minutes.

    Not that it makes any difference to me but why are you using Efke 25 with an 11X14 negative? Most people who shoot big sheets of film shoot fast film for the reasons you mention.
     
  3. Mike A

    Mike A Member

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    Thanks Donald, I grabegrabbed stuff up from J&C for two reasons. First, I heard about some of its characteristics and wanted to see how it would behave. Second, I'm a cheap impatient bastard that couldn't waite another promised month for the PL100 that will never be cut to size.

    Is there some where here or anywhere else that well tell me how to formulate the conclusion you came to here? {If you are at four minutes then a one and one half stop adjustment would be ten minutes.}

    Mike
     
  4. scootermm

    scootermm Subscriber

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    mike
    my suggestion would be to do some testing (I know it sounds expensive) but given the differences in developing that each person has in their work method. Maybe say, if you get a meter reading of 30secs at F45... try exposing for say 2mins and 4mins and develop them identically. See which gives you the best exposed negative.
    my experience has been that a 30sec meter reading requires a 2mins exposure. a 4 min meter reading would need approx 30-40mins. But like I said prior, often times peoples developing techniques, developers, trays v. rotary, etc, all this stuff can likely play a part in it.
    not exactly a literal answer to your question, but it might be a good idea to do some testing, and would likely be worth the sheets of film.
     
  5. Donald Miller

    Donald Miller Member

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    Mike since stops are the doubling or halving of exposure...and since exposure can be a measure of time or of the size of the lens aperture, then a one and one half stop adjustment to a four minute exposure time would be one stop...an additional four minutes and one half stop an additional two minutes. These are added to your base time of exposure to arrive at ten minutes.

    I haven't used this film myself so I don't know if these are accurate reciprocity adjustments. However, I respect the products and information that John at JandC provides.

    In reciprocity situations, it is also wise to adjust development. This is due to the nature of an exposure having various luminance levels under reciprocity conditions. The more luminous regions of the exposure would receive proportionally more exposure then the darker areas. So this leads to an exposure having more inherent contrast then one would normally assume. As the length of the exposure increases and the reciprocity adjustment increases then the development time is adjusted in ever incremental amounts. Of course since the length of exposure and reciprocity adjustment add increasing amounts of contrast then the development time is adjusted downward to compensate.

    As an example of the adjustment, Kodak makes the following recommendations of adjustments to developing time for their film Tri X under reciprocity conditions. For one stop of reciprocity adjustment, decrease development by ten percent. For two stops of reciprocity adjustment decrease development by twenty percent and for three stops of reciprocity adjustment decrease development time by thirty percent. These times and adjustments should be considered as starting points.

    By the same token, I think that it is improper to assign garden variety reciprocity adjustments to all films. Each film will have it's own characteristics. For instance TMax 400 is noted for it's excellent reciprocity characteristics and if the adjustments previously ascribed were used you would end with a negative that would be over exposed to the point of being unuseable.
     
  6. Mike A

    Mike A Member

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    Thank you Matt and Donald, I think this might indeed burn a couple or more sheets of film. Testing as Matt suggested along with Donalds reciprocity explanation seems to be my only option.

    Mike
     
  7. argus

    argus Member

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    I have similar timings.
    And don't forget to incorporate longer exposures for the bellows extention before computing the reciprocity correction.

    Close-ups metered at 30" quickly become 10'.

    G
     
  8. noseoil

    noseoil Member

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    Mike, I think I may have made a suggestion of getting a box of 4x5 Efke 25 to try with your processing trials, if not I apologize. I would still rather you work out the numbers with 4x5 to see what happens than using a very large film in unknown territory. Best, tim
     
  9. Poco

    Poco Member

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    Yeah, working with smaller film for testing would be my advice as well. You can even cut a larger sheet into pieces and tape it into the film holder, only make sure to tape opposing edges so film curl doesn't catch the darkslide and pop it off (happened to me once).
     
  10. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    Or, if you're too impatient to order some 4x5" and don't have the ability to cut down a sheet of 11x14" precisely, you can make a test strip for exposure in camera by pulling the darkslide a couple of inches at a time for whatever interval makes sense for your test. Maybe start with the metered exposure plus one stop, say, and pull in one minute intervals, or you can make the strips vary by a half stop each if you calculate it in advance remembering that the last strip will have the shortest exposure. Or alternately start with the darkslide out and insert it a few inches at a time--whatever's easier.

    Once you figure out a base exposure for reciprocity, you can run development tests for contrast.
     
  11. Steve Sherman

    Steve Sherman Subscriber

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    I'm not much for testing, that said here's my 2 cents.

    Probably 80% of my photography requires reciprocity adjustment. THe first thing I would say is, yes reciprocity does increase contrast, that's what's so great about it, I like to call it reciprocity success rather than failure. Therefore, why would you decrease development, hopefully not because Kodak says to. Unless you are photographing nighttime scenes with dark shadows and bright street lights there is no need to decrease development. In fact many times in the light I make photographs in I often increase development to effect more edge contrast. I would suggest that most of us experience reciprocity where exposures increase because of low light levels, trypically where contrast itself is reduced.

    For years I used a reciprocity chart given to me by my friend Jay Dusard. It worked everytime when I was silver printing. Recently I have switched to Azo. With Azo's ability to separate deep into the shadows I got the feeling I wanted more exposure. I have sinced switched to another reciprocity chart. I'll give you a few conversions here and can attest that these work wonderfully with J&C 200 and Semi-Stand development and printed on Azo.

    Try these: 1sec. = 2 sec. / 2sec. = 5 sec. / 4 sec. = 15 sec. / 8 sec. = 35 sec. / 15 sec. - 1M 20 sec. / 30 sec. = 3M 30 sec. / 1M = 8M 45 sec. / 2M = 23M / 4M = 55M / 8M = 1H 35M.

    I make photographs not tests and can say I am very pleased with my results, everytime.

    Hope this helps
     
  12. noseoil

    noseoil Member

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    Good amount of information here, but I need to add a note of caution about Efke 25. Donald has mentioned Kodak's suggestion about reducing development, while Steve has mentioned a need for increased contrast in much of his work. Aren't we are talking about a seemingly similar situation with respect to reciprocity?

    I don't have a fraction of the background in Donald's testing, equipment or experience, and I certainly don't come close to what Steve has been able to accomplish with his methodology, so please take these observations with a large pinch of salt. My only experience comes from working with Efke 25 for two years. Donald's statement about Kodak is based very specifically on Tri-x, a film which can be developed to expand about a stop and a half. Steve has been working with J&C's 200, another film which is not capable of large amounts of plus development, in my understanding. The wild card here is Efke 25. It is a slow film which builds contrast beyond most other film's capabilities. I think Donald has mentioned in a previous thread about it being capable of building more contrast than is necessary for most, if not all, current photographic materials used today. He had mentioned a number, but for the life of me I can not remember it. This includes silver printing, as well as alternative process materials. My point here is that we are at times in uncharted territory with respect to differing films, contrast levels of light and exposure. Finally the film's tendencies with respect to development are another variable.

    Perhaps Donald can help us out with a few numbers, by way of an example, which would compare Efke 25's potential contrast scale to that of Tri-x, since I can't. I think this might be helpful to those of us without a background in sensitomitry and the numbers which mean so much to various papers. Basically, Efke 25 can build contrast in flat light that other films can't come close to matching. I think in some respects here, we are comparing apples and oranges when we talk about different films and how they react to light and development. This is the wonderful thing about film and light. Just when we think we have figured it out, a new situation appears and we have to think very hard about how we can deal with it to make a good print. tim
     
  13. Donald Miller

    Donald Miller Member

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    Tim,

    While I have never used Efke 25, I have experience with one of the rebrands of the material identified herein as JandC 200. In my experience and the experience of many other photographers the material identified as JandC 200, while a nice film, has the limitations of building a density range of about 1.75 or slightly above. While, when one views, the data that JandC provides it shows that Efke 25 is capable of a DR exceeding 3.0.

    I am not surprised by Steve Sherman's comments to this thread for several reasons. The first is that, on the basis of previous observations of his attitude and responses, he has an almost antagonistic response to anyone who avails themselves of objective knowledge of materials. Second he seems to parrot the words of many of the DBI photographers who have chosen to follow the Smith approach to photography.

    The unfortunate thing is that this approach does not lead to a good knowledge of materials and their characteristics. Certainly not sufficient to intelligently discuss the matters in sensitometric terms. For instance, JandC 200 will never build density range beyond gamma infinity no matter how long you expose it and how long you develop it. Gamma infinity for that material is what I expressed prior.

    Efke 25 by the same token has far greater expansion potential...far better suited for the Azo printer provided you can live with the spectral response and the slow speed of the material. But then the person who does not avail themselves of the published characteristics of a material would not know that other then by trying the material under actual conditions. That would lead in many cases to wasted money and time testing materials that are not well suited to a given process.

    Now on to my earlier comment about reducing development under reciprocity conditions. That is known and used by knowledgeable photographers who have grasp of their materials and who wish to arrive at consistancy in the density range of their camera negatives under varying conditions. By contrast, for those who are disciples of the windage and elevation school of sensitometry it makes little difference.

    Now on the subject of the reciprocity compensations that Steve kindly provided and strongly suggested we use, I will acknowledge that they may work for certain films...but certainly not all films. In fact I would suggest that they may prove counter productive for certain applications. I would take those suggestions under advisement subject to my own testing of the materials that I choose to use. To do otherwise is irresponsible in my opinion.
     
  14. Steve Sherman

    Steve Sherman Subscriber

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    I thought long and hard about getting involved with this thread. However, I thought I might be able to share some practical experience and application. Wrong again.

    I certainly don’t think I was being antagonistic in any way, if I came across that way, my apologies Don. I merely meant that Kodak has lead us down the road of mis information for ever beginning with the speed of their films.

    I intended to share with those interested my experiences with regard to reciprocity. I have used Tri-X, FP-4 extensively and Hp-5 and J&C 200 recently and can attest that their reciprocity characteristics are similar.

    I don’t have the energy or inclination to argue objectivity about a subjective meduim. I know what has worked for me for years and hoped to enable others with practical experience and application.


    It really doesn’t matter whether you embrace SBR methods or Zone System concepts, what matters is the prints. It's too bad not everyone realizes that.

    “disciples of the windage and elevation school of sensitometry” Classy comments Don, I’m sure we’ll all here about your tests and results won’t we… do you ever make a damn photograph?
     
  15. eddie gunks

    eddie gunks Member

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    mike,
    i shoot alot of pinhole photos so reciprocity is familiar. i tried the efke 25 film the other day http://www.f295.org/Pinholeforum/forum/Blah.pl?m-1139058987/s-0/highlight-/#num0 for a linkto my question.
    i suggest you download and use the pinhole designer http://www.pinhole.cz/ this is really great, and very helpful. it was suggested that efke 25 is about the same as TMX 400, so you can plug in your info and it will create a chart for you to determine your exposure. i found te chart to be very close. i hope this helps.

    eddie
     
  16. Mike A

    Mike A Member

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    Ok,
    Tim, again your input regarding this film and my questions are appreciated.

    Donald, I respect your technical posts here and I thank you. I realize you are a Phill Davis disciple and I myself have been trying to absorb his book I have recently received, although the BTZS Light CD that came with the book does seem inviting.

    Steve, I think it goes with out saying that the work and testing you have published on this forum has been appreciated and used by myself as well as many others. Steve thank you for your input.

    Mike
     
  17. Allen Friday

    Allen Friday Member

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    Above, Donald Miller writes: "If you are at four minutes then a one and one half stop adjustment would be ten minutes." This is just wrong.

    If you are at four minutes, then one and one half stops would be 12 minutes. Donald made a rookie mistake. Each stop is a doubling of the light from the stop before it. Hence, when you go from 4 min to the next stop it gives you an exposure of 8 minutes. The 8 minutes is then doubled to give a two stop increase to 16 minutes. It is not 4+4+4, it is (4x2)2. Half a stop between 8 and 16 is 12, not 10.