Test strip print calculator

Discussion in 'Darkroom Equipment' started by Rhodes, Dec 15, 2013.

  1. Rhodes

    Rhodes Member

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    http://www.firstcall-photographic.c...rip-printer-print-projection-calculator-scale

    Is it worth to get one for the exposures tests? Or can I make one in a transparent acetate sheet? I getting a bit of trouble in doing the traditional way, the print always come ups to dark. I cover almost all the paper, expose for 2 seconds, then slide the covering a bit and exp. 4s, then 8 then 12 or sixteen, etc. the final exposure is made with out any cover (right or wrong?) and that small last part should correspond to the 2 seconds, since the first one will always got light, corresponding to the longest exposure time and being the darkest. Yes? Or I am completely east of eden?
     
  2. pentaxuser

    pentaxuser Subscriber

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    If I have understood what you do then you gradually uncover the paper until at the end the whole paper is uncovered which means that the whole paper gets whatever exposure you give the last section so if the exposures are doubled each time and you give say 5 exposures of say 2,4,8,16,32 then the least exposure is the last with 32 secs and the most is the first with 32+2+4+8+16= 62 secs.

    No wonder that it is all too dark. Try 2 secs then cover that section then 4 secs and cover that section and so on. This will give you 2,4,8 etc which is your aim.

    It can get confusing. For the price of the Firstcall calculator you can buy a Paterson 5 strip printer which allows you to uncover then cover each strip for the exposure which is what I have tried to describe above. If you have to uncover then cover with plastic strips it is impossible to make mistakes. The Paterson also allows you to select the best part of the negative and then move the test strip printer each time so the same section of the negative is printed each time. All you do is close all the strips then move the printer until the second strip is under the same section of the negative then open that one for say 4 secs if the first strip was 2 and so on

    pentaxuser
     
  3. L Gebhardt

    L Gebhardt Subscriber

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    You want to cover the paper progressively as you make strips. So start with an uncovered sheet and make your first exposure. Cover a small strip, make another exposure, repeat until you have made strips on the whole paper.

    There are two schools of thought on the timing for the strips. First is equal number of seconds for each strip, so you end up with 2, 4, 6, 8, 10... This is easy to do with a regular timer, which is why it's popular.

    The second method involves using fstop printing so each strip gets exposed with twice as much (or some fraction of a stop) as the pervious strip. For example 2, 4, 8, 16, 32... As you can see in 5 strips you have covered a range of 2 to 32 seconds vs 2 to 10 seconds. In addition each strip will be denser than the previous one by an equal amount. The downside is with a regular timer it's difficult to get the calculations right.

    I recommend you stick to the first method for now. Make large strip increments to get you into the ballpark, then make another strip with smaller increments to fine tune the exposure. So start with a sequence of 10 second exposures so you will have a strip at 10, 20, 30, 40, 50, 60 seconds. Then, if for example the 30 is too light and the 40 is too dark make a second strip. Give the whole paper 30 seconds, and then make strips at 2 second increments. So you then have 30, 32, 34, 36, 38, 40. If the ideal looks to be between 34 and 36, then a 35 seconds exposure should be just about right.

    If you want to explore fstop printing I can recommend it, but I think it really requires a timer that supports it built in. There are many threads on the subject, but I wouldn't worry about it for now. The only reason I brought it up was your times you quoted looked like you might have been attempting something like this.
     
    Last edited by a moderator: Dec 15, 2013
  4. Rhodes

    Rhodes Member

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  5. Christopher Walrath

    Christopher Walrath Member

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    Just to be sure, you need to start with the long exposure first. My example is 32 16 8 4 2 1 1. I then get a test strip with 64 32 16 8 4 2 1.
     
  6. bernard_L

    bernard_L Subscriber

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    +1 you must cover the test strip in steps.

    Second section will get the initial 2+4=6. If third exposure is eight third section will get 2+4+8=14. So second/first=3x, too large ratio.

    What I do. Have a stopwatch with three nice big pushbuttons start, stop and reset. I let the stop watch do the sums for me. One hand for the stopwatch, the other for the enlarger switch. Assume I want a sequence 2, 4, 8, 16 seconds. Expose whole 2s. Mask first cm (or 1/2 inch if you prefer). Expose until the stop watch is at 4s. Advance mask one step, expose until the 8s mark. And so on.

    Further remarks.
    (A) 2s is actually too short to be reproducible. Useful only for a first rough estimate. Aim for an exposure time of 10s at least; close the lens diaphragm if necessary.
    (B) When you need to nail down the exposure, you need finer steps for the intermediate times. I use 1/2 stops, which is not hard to memorize, because it's just the sequence of f-stops 2, 2.8, 4, 5.6, 8, 11, 16, 22, etc... Except the difference between two steps is 1/2 stop, not 1 full stop (as would be the case if you dialled these numbers on the aperture ring). With a paper grade 3 or more, I use 1/3 stops; also easy to memorize because it's the sequence of ASA/ISO sensitivities; but leave that for a later time once you have digested the basics.
    [C) You seldom have samples of important tones all present in the small area covered by a test strip. You may need to expose two test trips in different areas. Then develop/fix together; saves time.
    (D) Be aware of drydown: light print tones will be slightly darker once the paper is dry.
     
  7. markbarendt

    markbarendt Subscriber

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    I have one and yes they are really handy.
     
  8. Doremus Scudder

    Doremus Scudder Member

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    To the OP:

    Don't get confused by the seemingly contradictory progressions for making test strips. There are two different techniques at work here.

    Some (like me) start by giving the entire test strip a base exposure and then cover it progressively in predetermined intervals (like 2,4,6,8 seconds, etc.)

    Others (like Christopher Walrath above) start with most of the test strip covered and uncover it progressively. The intervals are appropriately different.

    Either method works fine, as does the print projection scale. Use whatever method is comfortable for you.

    FWIW, I like the flexibility of a test strip over a projection scale so I can use whatever values I like (plus I don't have to buy a projection scale :smile: )
    I also like a progression of percentages so that each strip is the same exposure difference. However, it really doesn't make that much difference. The main thing is to find a base exposure that you can begin with and make refinements from there.

    Best,

    Doremus
     
  9. Rhodes

    Rhodes Member

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    After a darkroom afternoon time, well I get a more normal results, but still not get a decent test strip. The trouble with the Paterson test printers is that it only exist in 4x5, and I am falling in love with 8x10 paper!
     
  10. Christopher Walrath

    Christopher Walrath Member

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    No sweat. You do not need to cover the entire paper with the printer in order to get a good exposure indicator. Just make certain to center it under the projection of an important portion of the subject. You will get enough to make a good determination.
     
  11. pentaxuser

    pentaxuser Subscriber

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    When you say that you are falling in love with 8x10 paper do you mean that you want to do 8x10 prints? The easiest way is to do what I think Christopher Walrath has suggested which is to project the negative as an 8x10 then place the Paterson test strip printer on the most important area which is usually one with a range of zones from shadows to highlights then establish the best overall exposure for the print and using the other strips which will be lighter and darker than the best exposure strip, establish burning and dodging times as well.

    pentaxuser
     
  12. Rhodes

    Rhodes Member

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    I am already doing 8x10 and 7x9,5 prints, due to have old 2 of 100 sheets paper boxes (almost full) and I'm using for the first prints, learning how to put the negs on the carrier, putting the easel right, errors, etc.
    Well, will look for a test printer and see.
     
  13. Christopher Walrath

    Christopher Walrath Member

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    If you want a test printer then by all means get one. Just realize you do not have to wait. If you are starting to print, then use one of the other methods mentioned above and get to the magic.
     
  14. pentaxuser

    pentaxuser Subscriber

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    +1 to what has been said above. Either Chris' method or Doremus Scudder's will give you what you need. You don't have to wait until you get a Paterson test strip printer.

    If you are good in a workshop or have access to a machine shop then have a look at Ralph Lambrecht's site called " Darkroom Magic" where he gives instructions for a 5x7 inch test strip printer. A workshop engineer could easily modify this to accept bigger paper such as 8x10 although I don't think this is necessary.

    What might be advantageous is an opening in the test strip printer which gave you an inch and a half or even two inch strips with longer paper such as 5x8 inch( a 8x10 cut in half on the 10 inch side) so you would still have four sections of two inches or even 4 x 10 inch( 8x10 cut in half but on the 8 inch side) so you would have five two inch sections.

    Best of luck and tell us how you get on. Once you get the right test strip things will get better

    pentaxuser
     
  15. Xmas

    Xmas Member

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    Well I use a soft graphite pencil and write 45 and draw a line above set the timer for 45 then place the card over the 45 up to the line write 50 and another line and give the paper another five...

    after dev and stop I have a record in fix bath...

    works ok on semi matt

    I split grade print so do several strips...

    And to tell the truth I scan twice first for straight A4 inkjet which I laminate and gloss with a Sharpie or China graph with scanner densiometry from 2nd scan.

    But I can still fill a waste bin with rejects over a week end, unless the neg is good.
     
  16. fotch

    fotch Member

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    I have one like the FirstCall but made by Kodak. Works well although I like the type moves the paper so you compare the exact same part.
     
  17. Sirius Glass

    Sirius Glass Subscriber

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    I have used something like that from Kodak for years. It is a useful tool.
     
  18. Rhodes

    Rhodes Member

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    I got one and other darkroom stuff that I need it! ALready used it and it's quite good thing to have!
     
  19. WayneStevenson

    WayneStevenson Member

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    I recently purchased some new ones to replace a couple old Kodak ones. They were getting very scratched up.

    On the new one, density was off. So prints were way off what the scale showed me. Took me awhile to figure out wtf...

    Problem with those print calculators are that they're small, and only give you a portion of your print. I have tried with multiples (as I have a few of them), but with pie wedges, they really aren't good for a lot of prints.

    If I were honest with myself, nothing beats test strips......