Jim, what kind of timer would you need if looking at quarter and half stop increases while printing? At first glance, I'd say a digital timer, but could you use this process for a "dial" timer?
"(Insert witty/meaningful/inspirational/silly comment here)" - J. Denney
Originally Posted by Mr_Rocketkiller
Check Ralph Lambrecht's site http://www.darkroomagic.com/ . Go to "Library" and arrow down to the timer wheel. It looks like it works on Gralab-type timers.
Otherwise, with other types of analog timers, you can use this chart for f-stop printing times:
If you are going to use f-stop timing for test strips, the chart found at Ralph Lambrecht's site (darkroommagic.com) works well, with one caution.
The chart is really set up to aid in doing fine adjustments, burns and dodges, where you are adding to or subtracting from an already determined base exposure. When you are making a test strip, you don't necessarily have a base starting point, and you are wanting to cover a range of possibilities. In addition, test strips work best if you don't start and stop - i.e. it is better to start with the whole strip uncovered, and then progressively cover more of the strip, at the required intervals.
This involves a bit of a challenge, because the fractional f-stops listed on the darkroommagic site are hard to accurately count with either a metronome or sweep second hand or in your head (I've never been able to get those 1/10 second intervals to come out right myself).
Also, when you are starting out with the entire strip uncovered, and then progressively covering more over, the segment times add up - if you were using the same interval (e.g. 4 seconds) the progression would be as follows:
1st = 4 seconds
2nd = 4 + 4 = 8 seconds
3rd = 4 + 4 + 4 = 12 seconds
4th = 4 + 4 + 4 + 4 = 16 seconds
What I like to do is to do my test strips in 1/2 stop intervals, and to use the (almost) standard f-stop progression on my lenses as a guide - i.e. 5.6, 8, 11, 16, 22, 32, 45, 64. To accomplish this, I set my timer to 64 seconds, turn on the "metronome" function, begin with the strip entirely uncovered, and then progressively cover over segments of the strip as follows:
1st = 6 seconds (entire strip uncovered)
2nd = 6 + 2 = 8 seconds (all but 1st segment uncovered)
3rd = 6 + 2 + 3 = 11 seconds (all but 1st & 2nd segment uncovered)
4th = 6 + 2 + 3 + 5 = 16 seconds etc.
5th = 6 + 2 + 3 + 5 + 6 = 22 seconds etc.
6th = 6 + 2 + 3 + 5 + 6 + 10 = 32 seconds etc.
7th = 6 + 2 + 3 + 5 + 6 + 10 + 13 = 45 seconds (last 2 segments uncovered)
8th = 6 + 2 + 3 + 5 + 6 + 10 + 13 + 19 = 64 seconds (last segment only)
To ease the process, I have a chart with the sequence of intervals by my easel: 6, 2, 3, 5, 6, 10, 13, 19 - in big, easily read numerals.
I use 6 seconds rather than 5.6 seconds to start because, well, I can't count 5.6 seconds with the necessary precision, but with the aid of the "metronome" on my timer, I can get pretty close to 6.
Once you find a segment that is close, you can then generally do a further test with finer divisions within that segment, using the chart (but again calculating the differences between sub-segments).
Hope this helps.
P.S. If any one else finds the 6, 2, 3, 5, 6, 10, 13, 19 chart useful, please feel free to make whatever use of it you wish - no copyright concerns here
Last edited by MattKing; 01-08-2007 at 08:14 PM. Click to view previous post history.
Reason: typo and add comments
Wow guys thanks for all the replies. I'm printing this discussion out because its got some great tips. I did find the darkroommagic site last night and am looking through it. Thanks all!!
There are _many_ ways to make a test strip, get 10 photographers and you'll get 20 ways.
Yet Another Test Strip Sequence:
Start with a sheet/strip of paper in the easel, then expose as follows:
- 5 seconds
Cover a strip
- Cover a strip
- Cover a strip
- 20 seconds
You will then have exposures at 5, 10, 20, and 40 seconds - pick the two best and make a 5 strip test:
5 - 10: every second
10 - 20: every 2 seconds
20 - 40: every 4 seconds
That will get you to within a 1/4 of stop with two test strips, and again sort of easy to remember: start with 5, then continue with 5 and double it every time 10, 20 -- if you need to go longer 40, 80 ... You can start with any value you like, repeat it and then keep doubling the times:
8, 8, 16, 32, 64, 128 ...
If the right exposure is between 5 and 10 then it's kind of tight to make a set of 1 second exposures without a digital timer. Best to stop the lens down one stop and try 10-20 every 2 seconds.
If 5 seconds is too dark close the lens down 2 stops, if 40 seconds is too light open the lens 2 stops.
A normal 5x7 or 8x10 print is somewhere in the neighborhood of 8-32 seconds at f/8. If your numbers are way different from that then something is wrong.
Once you know that exposures for 5x7 prints are just about always between say 7 and 15 seconds then you can usually start at 7 seconds and cover up strips at 2 second interfvals and get there in one strip.
If your negatives are really overexposed, they look _black_, you may have to use very long exposure times - don't be suprised if it goes into the minutes.
Getting an acceptable print isn't hard.
But there are lots of ways to make it hard, if not impossible, and that's what most discussions on APUG are about.
And keep good notes: scribble the exposure on the back of the print before you put it in the developer.
Allways develop prints for the same time: usually 90 seconds for RC paper.
If your developer gets old you may need to keep the print in it for longer periods of time to get a good print - don't give the print more exposure.
Same if the developer gets chilly - keep the paper in longer.
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And one here, it's the same principle just with numbers on it.
Originally Posted by Mr_Rocketkiller
You will find these things all over the web and in books.
Obviously there have been presented several approaches to the f-stop test strip. I do not argue with any of them. If it works for you, use it.
I do not worry about he fractions of seconds for quarter or half stop increases or decreases in time. My VC-CLS heads do have a built in timer which will account for them very accurately, but the college where I teach does not have this luxury and I revert to using a metronome which is the way I learned in the late 30's.
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Oh, reason for the numbers: if the pointer points to 3.7 and you want a .5 stops more then move the pointer to 4.2.
Originally Posted by Nicholas Lindan
With some of the others you count off 1/12 or 1/3 ticks on the timer face. To add a 1/2 stop count off 6 small ticks or 3 larger/large ticks.
People will go to war over this difference. The one you like depends how your brain is wired and what you are used to.
Is there one in 1/16ths for us hexadecimal users? To add 0.A stops to 1.E stops...
I think people should use whatever system works for them, but some of the suggestions here make my head hurt. My advice is to keep it simple.
Make a contact sheet of your negatives. Don’t worry too much about proper exposure (you can refine that later). The contact sheet will allow you to select images for enlargement and give you a good idea of where the highlights and shadows are. It will also tell you if your exposures are consistent and an idea of contrast.
First, pick one type of paper, one developer and one print size (I recommend 8x10 RC paper and Dektol). It shouldn’t take very long, regardless of the method you use, to arrive at a typical print time for an 8x10 print. You should adjust your aperture so that a typical exposure is around 20 to 30 seconds. This may sound like a long time when a wider aperture yields a proper exposure in 5 or 10 seconds but when you advance to dodging and burning you will get much better consistency with longer print times.
Now that you have done that, and you know that your average print takes about 25 seconds, make your test strip cover two or three steps either side of 25 seconds. I would use 2 or 3-second steps so if I decide on 2 second steps I would set the timer for 29 seconds, cover the strip except for about 1” and start the exposure. Every 2 seconds, move the cover sheet to expose another inch of the test strip. After exposing 4 strips, remove the cover entirely and let the exposure continue until the 29 seconds are up. Now you have a test that gives you 5 exposures at 21, 23, 25, 27 and 29 seconds. One of these should be very close. I see no need to use a whole sheet for this BTW. I would use a 4x5 piece and place it in an area that includes both shadow and highlight areas.
Using the exposure that looks the best, make a full size print without any dodging or burning. Later you can deal with paper grade and the other fancy stuff but when you start out you will be too excited for that and will want to crank out as many different prints as you can. That’s OK. I think the first time I printed; I made prints from about 20 different negatives in a few hours. That was 26 years ago. Now I only print one negative in a print session, if it is a new one, and I usually spend about 6 to 8 hours making four prints. More accurately, I spend about an hour making four prints and the rest of the time studying results, making adjustments and deciding if I have it just right.
Remember that the technical side of photography is 100% cause and effect. It’s not magic or voodoo or luck. Get the basics down and when you are ready, you can tackle the really fun stuff. Most of all have fun.