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LED Enlarger Head
As a photographer in the post-industrial age of darkroom equipment sometimes you have to take a problem into your own hands. That was the case last weekend when I finally had it with my Beseler enlarger heads. My condenser head is too weak to do 16×20 prints, and I hate how it picks up dust and scratches. My dichro 45 has a loose connection somewhere, and putting a vibrating fan on an enlarger head is a terrible design choice.
So I did a little Internet searching and found these, 500 lumen LEDs! I ordered 10 to be on the safe side. Now something to power them with. Certainly you can just hook up a power supply and a resistor and call it good, but really LEDs want to powered by a constant current source. The circuit I used is simple enough and should keep the LEDs from drawing too much current. I mounted the LEDs with thermal conducting
compound to the bottom of an aluminum project box, and attached a heatsink to the opposite side. I needed to build two copies of the above circuit to drive 10 LEDs. The reason is the power supply I chose was a 48V power supply, and each LED has a voltage drop of 9.6V at 700mA, my target current. So 9.6V times 5 is 48V. Of course the drive circuit has some overhead, so my end current won’t quite get to 700mA. One note on choice of power supply. The power supply I ended up using was a Vicor Flatpak switching power supply as it was the easiest to get that was 48V. My second choice was a standard power supply, but was only 12V which would have needed more circuitry. The problem with the Vicor is it take approx 500ms to reach 48V which doesn’t work for my burst method of enlarger timing. So I had to add an always on AC connection, and then another AC connection to a relay to switch the 48V faster
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Once I got the circuit built and the LEDs mounted I used the diffuser collar from my dichro45 mounted to the underside of the project box. The light looked nice and even so I gave it a trial run last night. For a 16×20 my exposure was 10 seconds at f16, way too bright! 5600 lumens is equivalent to more than 3 100W light bulbs. Of course that generates a fair amount of heat, my heatsink was hot to touch after 3 minutes of constant on. My choice of two separate driver circuits made this an easy fix, I just put a switch on the second driver circuit so now my enlarger head has a high and low.
Overall a pretty easy project, not my cleanest, but will certainly be heavily used.
Viewpoint Gallery Show
Metal Cone, Gladding McBean
My print “Metal Cone, Gladding McBean” has been accepted for the Gladding McBean exhibit at the Step Up Gallery at Viewpoint in Sacramento. Other artists in the show include Gordon Hutchings, Gene Kennedy, Mark Citret and others. The reception is Friday, February 12 and the show runs through March 6.
The print itself is a hand printed 16×20 silver gelatin matted to 22×28. I’m looking forward to seeing all the prints from this wonderful location.
Gladding McBean
This weekend I photographed some amazing industrial scenes at the historical Gladding McBean factory in Lincoln, California. This was a field workshop put on by Gene Kennedy and Viewpoint Gallery .
Friday night was orientation at the Viewpoint Gallery in Sacramento. It was a great introduction to see other photographers work from previous workshops. Saturday it was bright and early at the factory gate where we met and drove to the buildings we would be photographing in. There were about 30 or so photographers which seems like a lot until you realize how big this place is! After Gene gave a brief tour for the newbies we were set loose. I spent the first hour or so just wandering around looking at things. This place is overwhelming! There are historical workareas dedicated to terracotta reproduction, and very modern industrial areas that manufacturer clay sewer pipe. There is a huge building with wonderful beehive kilns, some working and firing, and some looking like they’re about to fall over. Photography continued non-stop until quitting time at 5 o’clock. Sunday morning same drill, this time I had an idea of what to expect and some notes and images I would like to make. I focused on those, but as so often happens I only touched on the surface of what this place could produce in terms of images. We will see how many keepers I get after doing my darkroom work.
I brought a mix of cameras to the workshop just in case. My DLC45, Nikon D80, Diane medium format and my trusty Canon G7. I wanted to shoot a series with my Diana but didn’t end up doing that. Instead I focused on my 4×5 black and white. I was distracted enough by all the wonderful potential images, I didn’t need to be bouncing back and forth between color and B&W, large format and “lomo style”.