View Full Version : Printing - change from test strips to 8x10 enlargement

Simon Rodan
2-Sep-2001, 21:09
Here's my problem: After making a number of test strips, I finalised the exposur e for the print I am working on (20 secsonds @ f11). Then I take a sheet of 8x10 and without altering anything (enlarger height, aperture, focus), I make the ex poseure and develop the print EXACTLY as I have the test strip, (2 minutes const ant agitation, 4 times the image appearance time). However, the shadows which w ere a nice rich Zone I on the test strip appear as Zone II or III on the 8x10.

I then make a repeat test strip to cehck that I have not done something silly and again the blacks fall on Zone I - then I make another 8x10 and again they r ise to Zone III.

This, as you might imagine, is rather frutating. Does anyon e have a suggestion as to what is going on.

Many thanks


pat krentz
3-Sep-2001, 00:55
Are you doing your test strips on a sheet of 8x10 paper also? There is a variable in there somewhere. Has the temp of your developer changed in the time it takes for you to finish your test strips? Pat

pat krentz
3-Sep-2001, 00:56
Developer temp, that is! Pat

3-Sep-2001, 02:35
Are you using a densitometer to check the exposure, comparing the strips and prints side by side or just eyeballing the 8*10? If the latter, I would bet that viewing the strips by themselves or against a light background will cause them to appear darker. The eye is not too good at absolute measurements and is better at differential comparisons. An example of this is a television screen. If there is a high contrast image displayed the blacks look very black but notice how grey the screen looks when the TV is off. If you think about it, that grey is made to look black only by the brighter parts of the image.

I have a wild idea about reflected light from your easel getting back into the optics and changing the exposure. The only way I could imagine this affecting the image is if you had an enlarger head with a light source that had some sort of feedback that actually monitored the light emitted and/or reflected. You don't have one of these fancy high tech head gizmos with an electronic controller perhaps?



David Vickery
3-Sep-2001, 03:02
Hello, When you place the strip on top of the full sheet do the tones really look different? Maybe your aggitation is more efficient with a small strip of paper than it is with a full sheet? Many times it is difficult to get an acceptable print when testing for the lower zones, it may be easier to first test for the proper highlight densities and then control the shadows areas with paper grade/filter.

Brian Ellis
3-Sep-2001, 11:53
Are you literally using a narrow strip of paper for your test strips? If so, there's quite a difference in the developer between developing one little strip and developing an 8x10 print. Obviously, with a little strip there's much more developer per square inch than there is with the print so the rate of exhaustion is greater with the strip. This would be particularly true if you have only a small amount of developer in the tray. If you are using just a small strip of paper (not a very good practice anyhow, IMHO, because it's so hard to tell much from just a small segment of the print), try making your test "strip" on a sheet of 8x10 paper and then comparing the results. Also, as someone else has suggested, the brightness of the area surrounding the shadows will have a big effect on how they look to you. In his Expressive Black and White Print workshop, John Sexton does a demonstration in which he makes a highlight of a print look brighter even though in fact it is more gray, by making the shadows around it darker.

David Richhart
3-Sep-2001, 12:15
Simon...Michael Smith has a great article that explaines how he prints, and determines printing exposures. It might change your methods completely! The website is at www.michaelandpaula.com

Best wishes -Dave

David Richhart
3-Sep-2001, 13:09
I have several emails from people wanting the specific URL of the Michael Smith address, so here it is...


All of the articles are well worth reading... but the one I refer to in this case is the one on printing difficult negatives.

While I am here I would like to take a moment to thank Michael Smith for his time in sharing his craft...-Dave Richhart

John Sarsgard
4-Sep-2001, 18:13
I second the suggestion to read Michael Smith's approach, but you might be more comfortable with test strips until you've got a bit more experience. FWIW, make sure the strips are from the same batch of the same paper as the full sheets. Paper varies from one box to the next a little (sometimes more than a little). As another poster mentioned, it's sometimes hard to judge a strip compared to a full sheet. David Vestal, who wrote an excellent book on B&W enlarging, and writes monthly in Photo Techniques, says he always gives the full sheet a little more exposure than the strips, but never understood why. Personally, I always use a full sheet, because judging density and contrast is just a lot easier for me looking at the complete image, even if it receives five different exposures. I can compare them side by side. You can also more easily judge how much the problem areas might need to be dodged/burned, because you have a variety of exposures all together. Run the strips vertically or horizontally or diagonally or whatever and try to get both highlights and shadows in each "band".

Kevin Crisp
4-Sep-2001, 19:20
Simon: Strange as it seems, I have sometimes found that 10X2 does not equal 20. In other words, a test strip which looks great at 10 exposures of 2 seconds each will sometimes look significantly different than giving the same material 20 continous seconds of exposure. The agitation comments above make some sense. Developer warming up in the tray makes sense, since the test strips tend to be earlier on in the printing session and the final print at the end.

R. McDonald
5-Sep-2001, 02:44

All of the above should be checked and let me throw another one into the mystery. If you are doing your test strips as most schools teach. The problem may be the heating and cooling of your light sorce. If you have a compensated light then you do not need to worry about this problem. If not,then you may want to think about how you do your testing. Before I had compensated lights, I had take this into consideration. So if I made my all of my test strips one right after the other(by 1 x set time, 2 x set time, 3 x set time and so on) my light would be warming up as I made the different test strips. And thenI would develope as normal(so thats some cooling time) and then I spend some time looking at the fine test strips to pick the best time (thats some more cooling time). So if I go back to make the full size Print,the darn light is cooled down. And if I choose a 15 sec exposure the light may have had 30 seconds of warm-up to produce the 15 second test strip! Just a thought.. Best of LUCK.. And do not forget to check out and follow thru on the recomendations in the above posts. Just try to do them one at a time to see where the problem for you,may be.


Simon Rodan
5-Sep-2001, 12:04
I would like to thank everyone who posted an answer for their great thoughts and advice. I now have a variety of tests to carry out this weekend. Thanks again. Simon