Test strip times and printing times
I have seen the Fred Picker printing video where he makes a test strip using 3 second exposures and instead of selecting a 21 second print exposure he will use 7 x 3 second exposures.
I have been trying the F-Stop method of making test strips (using a digital timer, not using technology like the RH Design products).
If you are also using the F-Stop method:
1) Do you make one expsoure for the total time? or
2) Do you repeat the series of exposures that made up the test strip? or
3) It doesn't really make a difference
Todd, Let me begin by saying that seven three second exposures do not equal the same as a single twenty one second exposure. The reason is that lamp start up and dimming effects enter into the multiple exposures.
In defense of Fred, F stop timing was not spoken of when he was with us. He also apparently did not understand the divergence from a total exposure in the method that he used.
Thus it would be most accurate to make your test exposures in complete units of stops and fractions of a stop that you determine. In other words do not work from accumulations of multiple exposures.
Just a simple observation and a question. If I tested printing times and the result was 7 three second exposures, why would I want to make the print another way?
Or another way, if you make a test (experiment) and it gives you a result you want why would you change it when you make the full print?
It does not make sense to test one way and print another.
I haven't seen the Fred Picker video, but assume he suggests incrementing the exposure in 3 second steps. Even Ansel Adams suggested this in one of his books. This sounds like the equivalent of bracketing film exposure times in steps of 1/7, 2/7, 3/7, 4,7, etc. I don't understand that logic. Film and paper respond logrighmatically to exposure. The difference between 1/7 and 2/7 is a full stop. The difference between 6/7 and 7/7 is a small fraction of a stop.
If I must make test strips from a problem negative, instead of fighting against the dictates of an electronic gismo, I use a clock that ticks fairly loudly every second. I start the exposure. After 2 seconds, I cover part of it. After another 2 seconds, another part. After another 4 seconds, another part, etc. This gives a sequence of 2, 4, 8, etc. Some may prefer a sequence of half stops, like 2, 2.8, 4, 5.6, 8, etc., or even 1/3 stops. Usually full stops gives me a good enough idea to interpolate the exposure and paper grade for the first full image test print. However, a cheap enlarging meter calibrated for flesh tones or the equivalent almost always suffices for the first full image test print.
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Originally Posted by Donald Miller
I am kicking myself
After all these years [size=3][color=blue]it finally dawned on me[/color][/size] as to why most of the time my test strips didn't match the density of my prints !!!! I'm so stupid. I knew about the enlarger bulb warm up time, but never thought to factor it in.......
Is there anyone else out there who has made or is still making this mistake, I need moral support by knowing you at least exist !
FYI f-stop printing times have been around muchl onger than you think. That is the way I learned to make test strips almost 70 years ago, and the method I teach today. It is just that no one had written about them until Gene Nocon came out with his timer and book.
[FONT=Comic Sans MS]Films NOT Dead - Just getting fixed![/FONT]
Somewhere I, too, adapted that way of making test prints long ago, but not quite 70 years back. My 7th edition (1967) of the once ubiquitous Lootens on Photographic Enlarging & Print Quality by J. Ghislain Lootens uses exactly the same system. So do Neblette, Brehm, and Priest in their Elementary Photography, 2nd ed., of 1942. I can't find earlier citations in my little library without too much searching, but suspect logarithmic test strips date back about as far as developing out paper. Why Ansel Adams persisted in advising equal, not logarithmic, steps as late as 1968 in The Print is a mystery, but it certainly worked for him.
Originally Posted by Jim Noel
If you're using a colour or VC enlarger with a voltage stabiliser there's quite likely to be a "switch on delay" of up to half a second, and that can seriously affect the accuracy of exposures if you use the "cumulative" test strip method. With such enlargers for example four 5-sec exposures very definitely do not equate to one 20-sec exposure. Our timers can be set to compensate for this effect.
Thus it would be most accurate to make your test exposures in complete units of stops and fractions of a stop that you determine. In other words do not work from accumulations of multiple exposures.[/QUOTE]
Donald is right, even the often maligned Kodak projection scale is designed for for a 1 mint exposure with times running from 2 to 60 seconds. I am under the impression that Ansal Adams set up controlled for blub warm up, I can get close with a tunston blub, but I still use the Kodak projection scale when using my cold light head.