Test Strips Question.

[smithy17]

Now that I have processed some negatives, I would like some advice how to make and read test strips before making enlargements. Do I test for light areas such as clouds or white clothing or buildings with details or expose for middle tones? :confused:

 

[Nige]

yep, expose for the light areas, adjust contrast to get your shadows right(ish)

 

[phaedrus]

You can even split the exposure between one for the highlights with the lowest gradation filter and one for the shadows with the highest gradation filter, a method called splitgrade printing. Provided, of course, you use multigrade or variable contrast paper. There's not much else left.
That method needs two test strips. The first one is for the highlights, it's done with the 00 filter. You take the exposure time that gives the highlights (not the specular lights, they can remain white) just a smidgen of tone. For the second test strip, you expose the whole strip with that time through the 00 filter and then expose a normal test strip through the 5 filter on top of that. The second exposure is the one that gives you the shadow details you want, with what you envisioned as Zone 0 going to black.
The first work print is done with the first exposure through a 00 filter and the second through a 5 filter. The two test strips also give some information for dodging and burning that can be done with either filter, depending on the effect you want.
Needless to say, you need a stable enlarger for this that doesn't change focus when you change filters.

 

[David Brown]

A test strip is just a series of exposures at different times to see what time gives the best print. "Reading" a test strip is nothing more than you deciding what looks best to you. Make a few and it will become apparent.

There are variations of the methodology. Using a set interval (i.e. X seconds) is the simplest. Some of us use F stop times, similar to the progression of shutter speeds on a camera. There is also the arguement about making al the exposures of the same area of the neg, as opposed to moving across the image (again, the simplist). Start simple and get fancy later.

 

[CBG]

There's a million ways to do test strips, so ultimately you will find what works for you. In the meantime try various schemes till one fits you. I use the generic test strip with a stepped range of exposures less and less, now only to get a ballpark paper grade and exposure, I include skies, highlights, midtones and deepest shadows all in the test strip so I can gauge what contrast grade will suit best. I use a broad range of exposures, say, 20 sec, 40 sec, 60 sec, 80 sec. Specifics on that will vary with the negative in question, what bulb, paper, degree of enlargement, time I am hoping will allow me workable burning times... I angle the easel so that a third sheet or a half sheet will allow me room to see telling zones in all parts of the test strips.

And here, my little twist, I use a medium size marker, a Sharpie, to write contrast grade, times, f stop, what paper it is, etc on the sensitive front of the paper before the exposure. Best if that data goes in the shadow areas, since the marker washes off in the fix and just leaves a white shadow of it's self, but that way, if I am making more tset strips that I would hope, I know which strip was what times, f stop, grades and papers etc... Also useful so that the test strips can be used later for testing toners, after processing, since the strips tell you what paper they are. Without written notes right on the front of the paper, I find myself unsure what strip got what treatment. It really helps.

 

[pentaxuser]

Smithy, if you haven't got one then the Paterson test strip printer is worth getting or better still have a go at making Ralph Lambrecht's test strip printer. It's on his website. Gives 7 strips from one 5x7 sheet and accurately and safely allows you to do all 7 from the same section of the neg. Having decided what exposure is right for the highlights, you can use the same printer for the traditional strips across the neg to get the right exposure for other areas for dodging and burning.

Probably worth doing the strips in seconds but as equal fractions of stops.

pentaxuser

 

[Anscojohn]

Now that I have processed some negatives, I would like some advice how to make and read test strips before making enlargements. Do I test for light areas such as clouds or white clothing or buildings with details or expose for middle tones? :confused:

*************
Unless you have already tested for your personal, needed film Exposure Index, get some base information first.

Make a test strip to determine the miniumum exposure through the clear film between negative images which produces maximum black on your negative.

When you have that exposure, make a test print on your target paper grade. If that print is too "dark," you underexposed your film in the camera. If it is too "light" you overexposed your film in the camera and probably over developed it as well.

Many people arrive at the ideal print exposer through a test strip of the high value, then change the print tone through paper grade or developer changes.
But having your baseline, benchmark exposure is important information to derive at the get-go.

 

[Nicholas Lindan]

Make a test strip to determine the miniumum exposure through the clear film between negative images which produces maximum black on your negative.

There are many ways to determine the right exposure and grade. "Minimum time for maximum black" is one of the simpler methods. Like most simple methods you can run into its limitations rather quickly. It is a good method to know, however.

I'd like to modify John's advice a bit... It is a good idea to have a usable 'max black' that isn't on the shoulder of the paper's HD curve - a statement that may not make a lot of sense to someone just starting out but it means you shouldn't expose the paper too much or you will loose detail in the shadows.

The steps:

After determining "min time for max black" with clear film reduce the exposure by 1/3 to 1/2 of a stop - say if the exposure was a 20 second exposure, use 15 seconds. You will have to determine the min/max time for each grade of paper you will be using.

Now expose a 1/4 sheet of #2 paper, or use a #2 1/2 contrast filter, to the important part of the image using the above time.

If the whites are gray and muddy then use a higher contrast paper grade or filter. If the whites are too white, and things look blown out, then use a lower contrast. If the blacks are muddy then increase exposure time 50% or so and try again. After changing contrast you need to use the min/max exposure time for the new grade.

Keep notes on the time you need for the min time/max black for each contrast grade. Make a note of the lens aperture and the magnification. For magnification use a ruler and measure the size of the image of the projection of whole negative on the enlarger baseboard/easel. As you change magnification you will also need to change print time.

The Darkroom Automation support page has a spread sheet that will calculate the exposure times for various magnifications when you have determined the min time/max black time for various contrast grades: maxblacktimes

The method won't get you a terribly good print, but the results will usually be workmanlike and you can turn out prints rather quickly after you have the method down pat.

 

[Doremus Scudder]

Good replies so far, especially John's and Nicholas's. I'll add my bit here to just to give you even more possibilities.

I use Nicholas's method for contact printing proofs. If you do this, you can see from the proof if the neg is over- or underexposed or if you will need a higher or lower contrast paper than the one you contact printed on.

However, when I get down to printing, it's the whites, i.e., the least dense areas of the print, that I base my exposure on (expose for the highlights, adjust contrast for the shadows). Here's what I do:

1) Choose a paper grade you think will work based on your "proper proof."

2) Select an area of the print to make a test strip from that has lots of lighter values. Use a generous strip. I like at least a third of a sheet if not a half-sheet.

3) Expose your test strip: I like to use approximate percentages when making a strip (some think in f-stops, I think in percentages). For example, a 20% test strip might go like this: 10 sec. base exposure then start covering the strip with a card for 2 sec. (= 12 total), 3 sec. (= 15 total), 3 sec. (= 18 total), 4 sec. (= 22 total), 4 sec. (= 26 total), 5 sec. (= 31 total), 6 sec. (= 37 total). Remember what you do so you can determine which exposure which strip got.

4) Develop for a standard average time, giving rather full development. Stop, fix and rinse for at least a minute.

5) Evaluate the light areas of your test strip under moderate illumination. Too bright will cause you to print too dark and vice-versa. People underestimate the importance of the evaluation illumination here. I like a 60-watt incandescent bulb about 4-5 feet from the paper. Choose the one you think renders the light areas best, keeping in mind that they will darken a bit when the paper dries (sometimes it's wiser to choose a slightly shorter time to compensate for the drydown, experience will be your teacher here). Often, I dry the test strip to be sure; I like 30 sec. on high in the microwave. Also, if none of the strips is to your liking, you can interpolate intermediate values. If, however, the proper strip is off one end or the other of your test strip, adjust aperture or time and make another strip.

6) Check the darker areas in the strip you have chosen as best. If they seem alright, make a straight test print at your chosen exposure. If they seem way to dark or too light, then make another test strip on a lower or higher contrast paper. Often, it's better to make a test print anyway just to be sure. If you need to adjust contrast, do make another test strip. Shortcutting here will cost you time and money. Find the right exposure and make another straight test print at the appropriate time and aperture.

7) Now you are done with test strips and can start tweaking the print. Small adjustments in exposure, development, dodging, burning, adjusting contrast with filtration or different developers, etc., etc., etc.

Hope this helps. Have fun.

Doremus Scudder
www.DoremusScudder.com

 

[Nicholas Lindan]

Max Black Vs. Min White:

Basing exposure on the highlights obviously gives a 'better' print as the highlights are more sensitive to small variations in exposure. However, there is the need to both make test strips for exposure and guess at the contrast grade.

The max-black approach, however, results in a decent 'drugstore/snapshot' print without the need for test strips - which is why it is used for contact sheets. There is a need to guess for contrast when making the final print. Making contact sheets at the same grade all the time allows easy judging of the approximate contrast needed for the final print.

Metering reduces the number of tests and guesses.

 

[smithy17]

Thank you folks for your advice. A lot of things to think about here, concerning film and paper exposure and processing.
It would be nice to read a publication like "Black & White Film and Paper processing for the technically challenged"
Seriously though, I will just have to play around and see how things turn out.

 

[Nicholas Lindan]

Seriously though, I will just have to play around and see how things turn out.

Exactly the right approach.

"There is nothing - absolutely nothing - half so much worth doing as simply messing about in the darkroom, well, except for boats."

- K. Grahame; "The Wind in the Bellows"

 

[naugastyle]

Agreed on the "play around and see how things turn out." You won't know what works for you until you get more into it. When I was in high school/college it never would've occurred to me there was more than one way. After a VERY long break from printing, these days I only make test strips for fiber but if I'm making work prints on RC, I just push forward with a 5x7 or 4x6 print w/o testing. I find I've almost always estimated correctly--even when split-grading or a lot of dodging/burning is involved. You just eventually learn how your particular combination of negatives, paper, enlarger and chemicals work together.

 

[MattKing]

"Play around and see how things turn out"

A good idea, as long as you add: "Keep Notes"