Have you ever taken long-exposure photos of the stars at night? Iâve done a little. Iâll do more now that the weather is warming up. During the colder months though the lens would fog up. And not just on the outside. Getting condensation *out* of a lens is not easy and takes a while.
This little project is to build a small heater to be wrapped around a medium-sized lens for a 35mm film camera. It will use a length of nichrome wire and a small battery pack to produce heat. A layer of neoprene rubber from a beer-can cooler will insulate the lens and heater wire.
- Nichrome wire
- 1.5mm green heatshrink tubing
- Powertech 2400mAH AA x 4
- 4xAA battery holder
- Jiffy box, 130 Ã 68 Ã 41mm
- SPST mini rocket switch
- Red and black 4mm banana right-angle plugs and sockets
- Red and black light duty hook-up cable
- 1A panel meter
- One beer cooler
Link #1 (below) talks about building a 45W heater for the correcting plate on a 14" schmidt-Cassegrain telescope (SCT). Scaling down the area to a 60mm diameter camera lens (355.6Â² / 60Â²) gives about 1.28W. The configuration Iâve come up with (spreadsheet) is 4 AAâs at 1.2V each, giving a maximum of 4.8V. With 6 turns around the 60mm camera lens, it should produce almost 1.5W. This should be enough power for a camera lens. Compared to a telescope mirror or correcting plate, a camera lens has a higher proportion of volume to exposed at the front.
Preliminary construction plans
A rough overview of what I plan to do:
- Cut open beer cooler. Cut the seam up the side and one around the bottom. Discard the bottom piece. Trim to fit desired lens(es).
- Place a length of the nichrome wire inside the heatshrink tubing and heat the tubing to insulate the wire and make it more managable.
- Bend the wire into a zig-zag pattern the right size for the beer cooler.
- Sew and/or glue the wire to the inside of the cooler rubber.
- Sew on velcro strips to the outside of the cooler rubber.
- Hook up power leads.
- Wire up jiffy box with the amp-meter, battery pack, and connectors.