Reciprocity Failure...

Discussion in 'Exposure Discussion' started by njkphoto, Dec 5, 2010.

  1. njkphoto

    njkphoto Member

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    Hi to all,

    I am about to develop film tomorrow and maybe this has been discussed so sorry. Well, I did some night photography last night using Ilford FP4 ISO 125 and Pan F Plus ISO 50. Exposures ranged from 8 sec to 30 sec..I did not add more time and I am wondering if I should develop the film more or you think I will get some good results as is.

    Thanks in advance.
    n.
     
  2. Mainecoonmaniac

    Mainecoonmaniac Subscriber

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    I don't think there's reprocity failure with these relatively short exposures. I wouldn't worry about it.
     
  3. njkphoto

    njkphoto Member

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    Thanks for your reply. I was looking into the tech specs of the film on the Ilford site and I think I read something that you have to compensate for even 5 sec which did not sound right to me.
     
  4. heespharm

    heespharm Member

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    [​IMG]


    Fp4 and hp5 have the same reciprocity
     
  5. dasBlute

    dasBlute Subscriber

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    In my experience, both of these exposures would require
    alot of compensation with FP4 [I've never used panf for night work].
    Additionally, at the higher exposure times, some underdevelopment
    might be helpful, N-1 or more...

    I use a chart developed by Gordon Hutchins, and this has worked on
    many an occasion. His recommended exposures for fp4 are:

    meter => suggested
    2s => 3s
    3s => 4s
    4s => 6s
    6s => 12s
    8s => 18s
    15s => 42s
    30s => 100s
    1m => 4m
    2m => 10m
    4m => 24m
     
  6. Bruce Watson

    Bruce Watson Member

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    Reciprocity failure is about the lack of photons. If you don't supply enough photons, you don't form a latent image. If you don't form a latent image, you don't have anything to develop. Therefore changing development time is a moot point.

    I think you'll find that no matter how you develop the film, you have empty shadow areas. This will be true because you didn't give enough exposure for the shadows.

    Depending on the image and your intent for it, this might not matter.

    If you want better reciprocity characteristics, consider using a more modern film, Acros, Delta, Tmax come to mind.
     
  7. Lee L

    Lee L Member

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    The image you've posted is an iphone 'photo' of a .pdf of an openoffice spreadsheet that was posted by me here on APUG: http://www.apug.org/forums/attachme...lable-sheet-films-bondregressionchart.pdf.att

    in this thread:
    http://www.apug.org/forums/forum37/60348-comparative-reciprocity-failure-available-sheet-films.html

    Please do not post it to flickr as if it were a image created and copyrighted by you. It's not either of those things. Please reference the original here on APUG with a link to the .pdf, and don't reproduce it on your flickr account. I want it to stay with the original text and in its original context, with proper credit and attribution to Howard Bond for the experimental data on which the spreadsheet is based, and to Patrick Gainer, as the formula I used is the same as a method he published in PhotoTechniques with one small change. The internet is bad enough about taking things out of context and without attribution without us making proper sources even harder to track. Information of this kind without context and attribution becomes meaningless and useless noise.

    BTW, my sources, among them Robert Reeves' Wide Field Astrophotography, test FP4+ and HP5+ as having differing rates of reciprocity failure.

    Thanks,
    Lee L

    P.S. I see that you've also included several iphone images of pages from an Ansel Adams book on your flickr account next to the one of mine that you took. That's not fair use, and you should probably remove them as well before flickr gets complaints.
     
    Last edited by a moderator: Dec 6, 2010
  8. mwdake

    mwdake Member

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    My experience with FP4 says there is definitely a need for reciprocity adjustment for measured exposure times of > 1 second.
    If you exposed a measured time of 30 seconds at 30 seconds I am not sure anything you with development will do any good.

    Here is my notes, I use the same times for FP4 and HP5.

    Measured New
    1 2
    2 4
    3 6
    4 9
    5 12
    10 32
    15 57
    20 01:26
    25 01:59
    30 02:30
    60 06:50
    120 18:40

    The first column is measured time in seconds, the second column is the time to use in minutes:seconds.

    You should try Fuji Acros sometime as it does not need any reciprocity for times up to about 120 seconds.
     
  9. njkphoto

    njkphoto Member

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    I wad just done a while ago developing the film. The results for the fp4 exposed between 15-30 sec were not bad at all. The Plus could use some additional exposure on some frames hut still good i think. I will post up some pics when i will scan and hit the darkkroom. I am thinking i will take a pic of the negative as well and post it.

    I did get some Fuji Acros and try it soon.
     
  10. njkphoto

    njkphoto Member

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    I just shot a roll tonight, (freezing) and used the above combination of times using FP4. I use D-76 and it shoots for 11 min. developing time. Since I don't wan't to blow the highlights how much should I decrease development? I am thinking 9 minutes maybe?

    Thanks
     
  11. heespharm

    heespharm Member

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    Duly noted and deleted... The AA pics were just for a friend to convince him to do the app... I couldn't find the original post but I knew I had the PDF somewhere... Sorry to offend
     
  12. Lee L

    Lee L Member

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    Thanks very much. I'm not offended. I just don't want the info stuck on the internet without proper context and without credit to the folks whose work I used to derive the results. Better to refer people to the original, and you have that info now. I know it's hard to find older posts here. APUG is in serious need of a much better search facility.

    Lee
     
  13. jp80874

    jp80874 Subscriber

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    It is early in the morning at this reading, but I don't see mention of what format you are using, simply “multiformat.” If you are using a view camera you may need to add a bellows factor. Search here and the large format forum if you are not familiar with “bellows factor”. If you have a large bellows you may need to add more exposure, several stops.

    When experimenting with night photography in any format, or even work in deep shadows, it is money well spent to bracket your exposures. By that I mean add at least two stops to the exposure you think addresses all of the above, including reciprocity. It is reasonable to assume that you can make a pretty usable print one stop on either side of the correct exposure. If your bracket is two stops more than the maximum exposure you think you need, this will give you a six stop range for your experiment.

    If this is not enough exposure then reconsider how you are metering. Consider a gray card, consider an Incident Light Meter which measures the light that hits the subject. It all boils down to the old standard “metering for the shadows, printing for the highlights.” If your first experiment doesn’t give you the detail you want, shoot it again with much more exposure and then bracket with two more stops (yes, doubling the time for each stop).

    The joy of experimenting in the neighborhood is that it gets dark every night. You experiment close to home, learn what you need, so that you know what you are doing when you go on an expensive trip. I hope this helps.

    John Powers
     
  14. njkphoto

    njkphoto Member

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    Thanks John I am using a 6x9 Mamiya. I am going to try the Neopan Acros now after using the FP4. As I said earlier I was surprised that I got a legitimate negative without any time change. Now, since I used the times from the chart above I am wondering if I should develop it a bit less from the 11 minute it calls.
     
  15. jp80874

    jp80874 Subscriber

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    Sorry. Can't help there. I use HP5 or T-Mx 400 and Rollo Pyro in a Jobo CPP-2. There is no grain that you can see in 7x17 contact prints. I have read that Neopan Acros has much better reciprocity characteristics that HP 5 or FP 4, but it is not available in the size I shoot, so I have no personal experience.

    John
     
  16. njkphoto

    njkphoto Member

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    Yeah I got some Acros and according to the specs there is no need for time compensation up to 120 seconds. I will try it soon. Again, it was interesting to see that the results on the FP4 were good at 8-15 seconds with not change in time at all.
     
  17. Jeff Bannow

    Jeff Bannow Member

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    I think you will find when you print them, that the shadows are too thin.