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Basic Darkroom Techniques: B&W Test Print
The first step to making a Black&White print is to make a test print or test strip to determine the correct exposure and contrast grade for your print. The contrast is controlled by different grades of graded papers or different filtration for variable contrast (VC) paper. The higher the contrast grade, the more extreme the differences between black and white in the print.
You need:
- Negative to print
- Enlarger
- Enlarging Easel
- Focus tool
- Paper-safe
- Enlarging Paper (VC or graded) in the papersafe
- Sheet of cardboard large enough to cover an entire sheet of paper (I use the cardboard the paper came in)
Steps:
- Place the negative in the carrier.
- Turn on the enlarger lamp and adjust the height of the enlarger to project the size print you want.
- For VC paper, set the filtration for a grade 2 (based on the paper manufacturer's recommendations), for graded paper, use grade 2 to start with.
- Focus the enlarger at this height with the lens fully open (smallest numbered f-stop)
- Set the enlarger lens f-stop to a setting in about the middle of the f-stop range. (if you have a lens that goes f4, f5.6, f8, f11, f16, then use f8 for example)
- Turn off all the white light in the room, you can have a tested safelight on.
- Remove a sheet of paper from the paper-safe. Place it (emulsion side up) on the enlarging easel.
- Expose the entire paper for one unit of time.
I use 3 seconds as a unit of time.
- Using the cardboard, cover about 1/5th of the paper.
When covering the paper, think about the blacks on your print, you want to get them right during the test process, so make sure you are exposing the blacks across the test sections. In other words if there is a black stripe running across the bottom of the print, then you want to create vertical strips.
- Expose the paper for another 1 unit of time.
- Move the cardboard to now cover 2/5ths of the paper.
- Expose this part of the paper for 2 units of time. (6 seconds if you are using 3 for the unit of time)
Quick aside: I recommend doing steps in multiples of the same number of seconds. The resulting test will be in exposure stops, rather than portions of stops (the difference in exposure between 24 seconds and 27 seconds is minimal)
- Move the cardboard to now cover 3/5ths of the paper, and expose for 4 units of time.
- Move the cardboard to now cover 4/5ths of the paper, and expose for 8 units of time.
When you are done, the sheet will have 5 strips
| Amount Covered | Creates Strip# | Units of Time | Total Units Time |
|---|
| 0/5 | 1 | 1 | 1 |
| 1/5 | 2 | 1+1 | 2 |
| 2/5 | 3 | 1+1+2 | 4 |
| 3/5 | 4 | 1+1+2+4 | 8 |
| 4/5 | 5 | 1+1+2+4+8 | 16 |
- Develop, stop, fix, wash and dry the print.
If the print is not dry when you look at it, you will need to allow for "dry-down" later, so it's best at first to dry the print (you can use a hair-dryer) to make sure you are getting the exposure you want.
- In normal white light, not just the darkroom white light, examine the print to determine which section of the print is the best exposure. It might not be perfect at this time, but this is the starting point. What you are looking for is a black area that is as black as you want it to be without losing detail. Don't worry too much about the white areas yet.
- If the best exposure is the first or last section (1 or 16 units of time) then make another test print. If the best section is the first one, close the lens 2 stops (f8 becomes f16 for example), but if the best section is the last one, open the lens 2 stops (f8 becomes f4) before you make the new print. This will give you a better choice of exposure times.
- You should now have a print that has a "best" exposure time surrounded by one section that is too light and another that is too dark. Now we want to refine the exposure time, this next process will make those refinements in quarter steps.
I originally wrote this as follows, but thanks to Simon Freidin, I've rewritten it differently, with different formulas. The original formula results in 1/2 stops between the first 2 strips, 1/3rd stops between the 2nd and 3rd strips, 1/4th stops between strips 3 and 4, and 1/5th stops between the last two strips. This doesn't give the level of detail that is really desired, but is simpler to do.
If there is enough room on your enlarger lens, close the lens down 2 fstops (f8 becomes f16), if not, close it 1 stop and use 2 seconds as your new exposure unit of time, if you can't close it even 1 stop, then use 1 second as your new exposure unit of time. Now make another test print using your new exposure unit of time and f-stop,However make the first exposure (of the whole paper) be the same as the lighter strip.The overall print gets a "base" exposure equal to that which created the lighter of the two strips you are trying to get steps between. The example below is based on doing 3 seconds at f8 for the first test print, and deciding that the best area is somewhere between strip 3 and strip 4. (strip 3 got 12 seconds, strip 4 got 24).
| Amount Covered | Creating Strip# | Exposure | Example Exposure | Example total exposure converted to f8 |
|---|
| 0/5 | 1 | Base | 12 secs @f8 | 12 s@f8 |
| 1/5 | 2 | Base+1unit | 12 s@f8 + 3s@f16 | 12.75 s@f8 |
| 2/5 | 3 | Base+3units | 12 s@f8 + 9s@f16 | 14.25 s@f8 |
| 3/5 | 4 | Base+7units | 12 s@f8 + 21s@f16 | 17.25 s@f8 |
| 4/5 | 5 | Base+15units | 12 s@f8 + 45s@f16 | 23.25 s@f8 |
The last exposure is not exactly the same as the one from the first test, but you can see that it is very close
This seems like an awful lot of testing... However once you get your process refined you'll be able to jump right to this last test print. Refining your process includes the development of the negative and looking at the proofsheet.
This is the new version, which has better results, but requires a bit more math in the process
The object is to get each of the test strips on this next test page to be in 1/4 stop increments between the two closests strips from the previous test print.
Divide the exposure of the lightest of the two strips by 16, and use that as your increment. That number may be rediculously low (ie. 3 seconds at f8 divided by 16 is .1875 seconds at f8) so you will adjust the f-stop to account for it (.1875 seconds at f8 is .375 seconds at f11 or .75 seconds at f16 or 1.5 seconds at f22 or 3 seconds at f32). Calculate the new increment and then use it to make the next print as above (with the entire page receiving the base unit, which is the exposure which created the lighter strip closest to the one you are looking for). Here is a chart, for which I am grateful to Simon Freidin, which may explain it better.
| Between Strip 1 and 2 | @f8 | @f11 | @f16 | @f22 | @f32 | Total @f8 |
|---|
| Entire sheet | 3 | 6 | 12 | 24 | 48 | 3 |
| 1/5 covered | +.188 | +.375 | +.75 | +1.5 | +3 | 3.188 |
| 2/5 covered | +.375 | +.75 | +1.5 | +3 | +6 | 3.563 |
| 3/5 covered | +.75 | +1.5 | +3 | +6 | +12 | 4.313 |
| 4/5 covered | +1.5 | +3 | +6 | +12 | +24 | 5.813 |
| Between Strip 2 and 3 | @f8 | @f11 | @f16 | @f22 | @f32 | Total @f8 |
|---|
| Entire sheet | 6 | 12 | 24 | 48 | 96 | 6 |
| 1/5 covered | +.375 | +.75 | +1.5 | +3 | +6 | 6.375 |
| 2/5 covered | +.75 | +1.5 | +3 | +6 | +12 | 7.125 |
| 3/5 covered | +1.5 | +3 | +6 | +12 | +24 | 8.625 |
| 4/5 covered | +3 | +6 | +12 | +24 | +48 | 11.625 |
| Between Strip 3 and 4 | @f8 | @f11 | @f16 | @f22 | @f32 | Total @f8 |
|---|
| Entire sheet | 12 | 24 | 48 | 96 | 192 | 12 |
| 1/5 covered | +.75 | +1.5 | +3 | +6 | +12 | 12.75 |
| 2/5 covered | +1.5 | +3 | +6 | +12 | +24 | 14.25 |
| 3/5 covered | +3 | +6 | +12 | +24 | +48 | 17.25 |
| 4/5 covered | +6 | +12 | +24 | +48 | +96 | 23.25 |
| Between Strip 4 and 5 | @f8 | @f11 | @f16 | @f22 | @f32 | Total @f8 |
|---|
| Entire sheet | 24 | 48 | 96 | 192 | 384 | 24 |
| 1/5 covered | +1.5 | +3 | +6 | +12 | +24 | 25.5 |
| 2/5 covered | +3 | +6 | +12 | +24 | +48 | 28.5 |
| 3/5 covered | +6 | +12 | +24 | +48 | +96 | 34.5 |
| 4/5 covered | +12 | +24 | +48 | +96 | +192 | 46.5 |
You can make any of the exposures at any combination of time and f-stop. For example, between strips 2 and 3, you can make the entire sheet (base exposure) for 6 seconds at f8, the second strip (1/5 covered) for 6 seconds at f32, the next exposure for 6 seconds at f22, etc.
An easier way to think of this table, might be to stop down 4 f-stops and use the same number of seconds as you do for the base exposure. Of course, the difficulty comes in when your lens won't stop down 4 f-stops...
The entire table is available for download, right click on this link and select save as, once it's saved on your hard drive you should be able to open it in just about any spread sheet program (it's stored in sylk format - symbolic link). Here's Simon's notes: Hi Andy
Your page on making a test print has dramatically improved my print-making - thanks for posting the info
Enclosed "time" tables for refining test prints - from your descriptions. Spreadsheet in sylk format - open it in excel etc The 3-second table may be a useful addition to your page - cells are values-only (formula-free)
Other tables explore what appear to be vastly long times - but I sometimes need to to make pin-sharp16x20" (2-stops) prints from T400CN (1-stop) with warmtone paper (1 stop) and a grade 4 filter (2 stops).
I'm ignoring paper reciprocity failure - doesn't seem to affect the prints.
regards
Simon
This seems like an awful lot of testing... However once you get your process refined you'll be able to jump right to this last test print. Refining your process includes the development of the negative and looking at the proofsheet.
- After you have "refined" your test print, you know now pretty well what the best exposure time is for this grade of paper (yes, the exposure can change with different grades of paper).
- Make a print of the entire sheet of paper using your "best" exposure time and f-stop.
If everything worked well you're somewhere near the middle of the lens aperature range, and somewhere around 12 seconds of exposure, but this is not a goal, just an average.
- Look at the print and decide if the contrast is right (boy, that was easy to say!) You should have a print with blacks as black as you want them, if not, you need to refine your exposure time some more, but this time pick a better angle of movement of the cardboard across the page so that the results reflect the black area you see a problem with. Are the whites as white as you want them? Or are the whites "washed out" (detail lost)? If the whites aren't white enough you need a higher contrast grade, if they are washed out, you need a lower contrast grade.
- Adjust the contrast grade (skip this if the print looks good)
- For graded papers, the higher the grade number, the higher the grade, make a print using the grade of paper you want to try next (use the same exposure / f-stop as before, the differences are usually minimal, but you want to see if the change in grade is what you want).
- For VC paper, if you are using VC filters, then using the manufacturers recommendations, change to the filter you need for the new grade (I have a filter holder that clamps to the enlarger lens). If you are lucky enough to have a dichroic head on your enlarger (normally used for color work) you can adjust the filtration for the new grade, here are some sample filtration numbers which you can try as a starting point, or see the manufacturer's recommendations.
| Grade | Yellow | Magenta |
|---|
| 0 | 92 | 16 |
| 1/2 | 74 | 22 |
| 1 | 56 | 28 |
| 1 1/2 | 46 | 37 |
| 2 | 36 | 36 |
| 2 1/2 | 28 | 53 |
| 3 | 26 | 60 |
| 3 1/2 | 12 | 75 |
| 4 | 4 | 90 |
| 4 1/2 | 00 | 130 |
These figures are starting points, for more information see Calibrating Dichroic Color Heads for Variable Contrast Black and White Printing by Paul Butzi
Refine your print.
Now you're ready to consider burning certain areas and/or dodging some areas
Next you need to edge burn your print
And you should consider adjusting for drydown
Visitor Comments
The comments stated below are
not necessarily the opinions of Andy Hughes or DarkroomSource
If you're tired of looking at the clock or counting seconds yourself when you're exposing prints in the darkroom, grab yourself a metronome from a music store (a cheap one will run about $20). Then set it for 60 beats per minute, and you've got yourself a nice, audible second counter. It will click once a second. More consistent then counting yourself and I hate trying to see a second hand on a clock in low light.
Contributed by
on 1999-06-23 00:00:00
I might add to the metronome idea. If you purchase an enlarger timer, you might want to look for the metronome sound as an option. I use mine all the time for dodging and burning.
Contributed by
on 1999-06-23 12:00:00
Here is another comment I received from Simon about the testing procedure that I thought might be appropriate:
Hi Andy
Thanks for thanking me on your page. I didn't realise my little chart would inspire you.
Anyway - last night I went off to the club darkroom (Melbourne Camera Club's awesome darkroom). Doing a 12x16" print - used the test strip spreadsheet - well actually another version that's made for doing all tests at the maximum possible aperture ('cause my tests take long times). Do the test, select the refined strip, make a work print at f8 and ARGGH!! the print's way.... too dark.
So I'm discussing it with the Darkroom Guru (at 2 am - he was in a "I'll give you a hand" mood) and explain how I'm opening up 2-stops from f8 to f4 and he says "But the club's 50mm lens maximum aperture is f4.5 - not f4" - and of course, the one-third stop difference means all the @f4.5 base exposure times are actually too short - so the f8 equivalent is too long . Anyway a reasonably cheap lesson - only wasted 3 sheets of paper & 4 hours on this one. Another trap for young players you may like to add to your page.
So I've just designed a spreadsheet with the one-third stop factor taken into account - I'll try it tonight.
BTW, really VERY! nice! additions to the process showing how to do everything at one aperture or one exposure time or variations for each strip and how to deal with ridiculously short exposure times - not that I ever have any :-(
Time for version 5 of the spreadsheet - where I do the long tests at f4.5, no stopping down :-).
seeya Simon
[ Simon made two points of interest here, one is that you might not have a "standard" f-stop range on your enlarger lens, the other is that using a wider lens aperature shortens the exposure time, so don't just use f8, if your times are too long, then shift the scale by a stop or more - Andy ]
Contributed by
on 1999-08-25 00:00:00
Subject test strips: I was scanning negs the other day when it suddenly dawned on me that I should be able to use the scanned image to work out exactly what sort exposure and grade I would need in the final enlargement. The idea is to use the histogram function most programms offer. The finite values of the could be translated into some sort of useful information via a factor. I fear I am trying to invent the wheel again - Has somebody tried this and what experiences do you have ?
Please let me know if anyone can help me with this!
Kind regards
harald kahles
harald.kahles@t-online.de
Contributed by
on 2001-05-21 00:00:00
