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  1. #51

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    Quote Originally Posted by Bill Burk View Post

    It's better science to eliminate variables from testing. Flare is a variable that can easily be eliminated from the experiment by placing the Stouffer scale in contact. But I didn't come here to harp on that.
    Bill!
    i tried to follow your advice and take a photgraph of the stouffer by putting it right before the film plane into the filmback. i used a 150mm lens focused at infinity...
    into the filter holder of the kompendium i slid a transparent piece of paper (used for graphic illustrations, etc.) exposing the film during yesterdays cloudy sky 5 stops more than the lightmeter suggested. i developed for 5,5 minutes.

    Please check the results,...i don't know what happened...it look like i got so much flare...or is it a light leak inside the filmback/camera???
    because even the unexposed but developed part of the film has a density of 0.15
    ...considering that it could be that around 1/2 stop of fogging caused by a lightleak (or whatever??) damaged and will be damaging all of my filmtests...
    please correct me if i am wrong: measuring step nr. 1 on the original stouffer tablet is 0.06 + 0.15 flare/lightleak/whatever equals 0.21!!! so around the actual 0.22 (step 31) of yesterday's contacted stouffer on the hp5.

    i am pretty confused...
    Attached Thumbnails Attached Thumbnails hp5_1.jpg   hp5_2.jpg  

  2. #52
    Bill Burk's Avatar
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    0.15 B+F is not unusual. Could be light leak "due to handling". But it is something you could improve if that's the case.

    The 5.5 minute test is overexposed, because you didn't "capture the toe" but notice how the curve continues all the way into your steps 20-30. Your other tests in the screenshot were camera tests and they are flat after step 20... The continuation of the curve in all steps of the test are what makes it clear to me that you made a contact exposure for the 5.5 minute test.

  3. #53

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    Quote Originally Posted by Bill Burk View Post
    0.15 B+F is not unusual. Could be light leak "due to handling". But it is something you could improve if that's the case.

    The 5.5 minute test is overexposed, because you didn't "capture the toe" but notice how the curve continues all the way into your steps 20-30. Your other tests in the screenshot were camera tests and they are flat after step 20... The continuation of the curve in all steps of the test are what makes it clear to me that you made a contact exposure for the 5.5 minute test.
    Bill, the other tests shown in the spreadsheet are the ones, you charted on paper and were, like you said, 4 stops underexposed...i only replaced the 5.5 minute test with the densities i measured yesterday in the data sheet.
    i did the test from yesterday like Michael http://www.apug.org/forums/viewpost.php?p=1480607 because he got good results with that...at least what i can read out of his posts in this thread http://www.apug.org/forums/forum37/8...pplied-17.html

    Bill, what are you suggesting? to do the test (by contacting) the same as i did yesterday,...but use only a 3 stop overexposure on the lightmeter?

    ----------------------

    regarding densities...Ralph suggests to take absolute density readings...so to null the densitometer when there is nothing in the light path...so i did it that way measuring all the densities on the stouffer

    or

    is it better to take relative readings...nulling the densitometer to an unexposed piece (=B+F?) of the tested film and then read all the densities relative to that first null measurement...is that a reading relative to base and fog (so b+f is subtracted from the measurements)...?
    Last edited by qualsound; 12-16-2013 at 12:02 PM. Click to view previous post history.

  4. #54
    Bill Burk's Avatar
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    Quote Originally Posted by qualsound View Post
    Bill, what are you suggesting? to do the test (by contacting) the same as i did yesterday,...but use only a 3 stop overexposure on the lightmeter?
    Yes, you overexposed according to the lightmeter by 5 stops, and you are about 2 stops from reaching under 0.10 density in your results. So a 3 stop overexposure according to the lightmeter will get you the 2 stops you need to reach the toe.

    Don't worry about whether you zero on clear air or B+F. As long as you keep the information (for example noting B+F in your records), the math to convert from one method to the other is "addition".

  5. #55

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    Quote Originally Posted by Bill Burk View Post
    Yes, you overexposed according to the lightmeter by 5 stops, and you are about 2 stops from reaching under 0.10 density in your results.
    Bill, one question arises then...look at the densities from the test i did underexposing the films by 4 stops...how is it possible that i can not get under 0.10 density even at 4 minutes dev. time (0.12 and even 0.19 at 16 min. at step 31 on the stouffer) even if the film is underexposed by 4 stops...?
    Are you saying that these "low" densities from 0.12 up to 0.19 are caused by flare photographing the stouffer off of a window (that is the way i did it for my first try on film-testing)...?
    Attached Thumbnails Attached Thumbnails -4stops.jpg  

  6. #56

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    bill or anyone else can help? highly appreciated!

  7. #57
    richard ide's Avatar
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    Film base plus fog. Why would you want to get a density below .10. It is totally unnecessary. High contrast graphic arts films will do it, but not suitable for general pictorial work.
    Richard

    Why are there no speaker jacks on a stereo camera?

  8. #58

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    A few thoughts regarding this contacting test in the camera.

    -A longer lens may be preferable to reduce falloff and give provide more flexibility in usable apertures. In any case, large apertures should probably be avoided.
    -Use your compendium shade (or any makeshift device) to cut off the image circle area beyond the edges of the film. This will help reduce/eliminate camera/bellows flare.

  9. #59

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    Richard...is a density for b+f of 0.12 "normal" for a hp5+ developed for 5.5 minutes in ID-11 1:1....???

  10. #60
    richard ide's Avatar
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    Your b+f density will vary depending on all the variables which occur related to exposing and processing that piece of film. It is similar to an all over neutral density filter and when you make a print you burn through it. With your example, your density is pretty close to ideal.
    Richard

    Why are there no speaker jacks on a stereo camera?

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