Jonathan's blog

Today I bought and collected a second-hand Durst C35 enlarger. It needed a new bulb, and the manual says very little about bulbs except you must use a MELAMP 55.

Users in some forums, including this one, say that compatible bulbs are difficult to find, or expensive. A little research tells me that the correct bulb is 55W, with an E26 Edison screw fitting, and an R20 glass envelope.

Thanks to Don’s Bulbs, it was easy to find out that these are all standards, and R20 is more commonly known as R63 or R64, because the widest part of the glass is 63 or 64mm in diameter.

And I’m delighted to say that Tesco (and probably almost every other retailer of domestic bulbs) have R20 bulbs with an E26 screw – albeit in a 60W version. If you can cope with the tiny difference in power, you can pick up two of these for £2.

The only snag I can see is that these bulbs probably have a different colour balance from the original Durst bulbs. I print in black & white so it doesn’t matter to me, but it might if you were to print in colour.

A while back I took an interest in infrared photography, and I bought a couple of rolls of Maco 820c infrared film. Using infrared film involves a huge amount of trial and error, and unlike digital cameras, you can’t take one or two pictures and check after each one. You have to shoot a whole film.

My camera’s light meter seemed to be responsive to infrared light, so I let it handle the exposures. Unfortunately I now know that the readings were nonsense, because the film came out almost entirely blank. The pictures that I salvaged weren’t good enough for my photo blog but I did write about the experiment.

This time, with my last roll of Maco film, I decided against trying to do any formal kind of metering. I left the aperture either at f/5.6 or f/8, as it seemed sort of sensible. You don’t want the aperture too small, because the longer wavelength of infrared light will cause diffraction at the diaphragm more easily. Equally, you don’t want it too big because this makes the depth of field smaller. Focussing infrared is already difficult as you can’t see it with your eyes, and has to be done using a red dot on the focus ring. By having a larger depth of field, you can get away with a larger inaccuracy before it looks blurred.

I put the camera in bulb shutter mode and guessed at the exposure time, judging by how brightly the sun was shining, and how warm it felt on my face. I generally exposed for between 5 and 30 seconds.

This time – great success. Practically every image was exposed well. A handful were a bit under- or over-exposed and had lost detail in shadows or highlights, but what can you expect when you choose the exposure time by looking at the sky?

I took a few pictures of a fire in a chimenea. These came out completely blank, so I guess the fire wasn’t emitting anywhere near as much infrared radiation as I thought. I suppose while it feels very hot, it isn’t that bright to look at. The film is sensitive up to 820nm and the filter allows wavelengths longer than 720nm. This is a reasonably wide range, but it’s still “near infrared” (almost-red light) rather than “far infrared” (heat).

The end result is that I’ve created images that are ghostly and every bit as “odd” as I had hoped, from looking at other people’s work. You can see the best pictures from the film on my photo blog.

A while back, I bought a Conway Synchronised box camera which came with a Coro Flash included. More recently I managed to get hold of some flash bulbs for it, but had trouble using them.

Using a multimeter and some paperclips I tested each stage of the flashgun and the synchronised trigger mechanism in the camera and found that each stage of the system worked in isolation, but still no joy taking photographs with a flash. I think some of the connections were a bit loose due to corrosion.

I took the (very simple) flashgun apart and washed all of its copper connectors in spirit vinegar to make them red and shiny again. Most importantly, I found it was necessary to scratch the corrosion off the contacts of each bulb before use, using the handle of a teaspoon or similar.

Now I can enjoy reasonably reliable retro flash photography, using Philips Photoflux PF1b flashbulbs. They’re quite expensive but I bought 15 bulbs from eBay for about a tenner. They’re good fun to simulate “proper” retro photography.

A note to anyone who is old enough to remember this stuff from first time round: Sorry for being so excited about obsolete technology. I’m just discovering this stuff for myself and I think it’s great!