First posted 11 July 2012
I recently gave a printing masterclass at Warwick College here in the UK. I do these quite regularly on behalf of Ilford / Harman technology and one of the things that I talked about, gave me the idea for this blog post. I was explaining how I prefer my students not to set their darkroom timers to exposures of less than five seconds when making a test strip. I insist on this because I have seen too many situations where a student’s test does not match their print.
When an enlarger is switched on it doesn’t give full illumination immediately, there is a build up of brightness -which although short in duration, can be a problem. Similarly, at the end of the exposure there is a tailing off of illumination from maximum to nil. When longer exposures are given these slight differences are not important, but if a student was to do a test strip in one second exposures and then decide that ten seconds was the correct exposure, a ten second burst of light would be quite different from ten times one second exposures. For this reason, as I already stated, I don’t like to see my students setting darkroom timers for less than five seconds.
Another method to overcome this problem and the method I prefer for my own printing, is to switch the enlarger on for a few seconds to warm up (with a piece of black card under the lens to block the light path), then uncover the lens to begin the exposure, timing the exposure with a metronome. This way, the light intensity is constant even for very short exposures. With cold cathode enlargers I leave them switched on all through the printing session, as they take longer to reach full, and consisitent brightness.
Using a metronome allows for an even, consistent light source, no matter how long, or short, the exposure is. The important thing to remember is to move the card exactly on the second. This is obviously most important when short exposures are being used, such as when burning in. For this situation, -say when a number of different exposures are needed within the one image, I don’t have to stop and re set the timer between each exposure. I just cover the lens, then uncover when I’m ready and count the appropriate time.
I have used a hand held digital metronome for a long time, but recently it gave up the ghost and refused to work. I had been promising myself for years that I would buy an old mechanical one, as I much prefer the old ticking sound to a digital beep. Instead, I asked my brother to record an old metronome and I now have the sound on my phone. I can use it in any darkroom, I have it to hand at all times and I can hear it through an earphone if I’m working in a busy teaching situation.
For those of you interested in trying this method, I have a 35 minute recording available for download; https://dl.dropbox.com/u/88621650/tiktok.mp3