How to make DIY lens heater for astrophotography - dew preventer

Tutorial how to make your own DIY heater for warming up lens during cold but humid nights. More often than not, at some point - lens cools down and collect moisture in form of condensate, not only on lens, but all over the camera. Camera is easy to protect with plastic (polyethylene) bag, cut from both side - something like a sleeve. Water will condense on surface of the sleeve, but not on the camera. Other problem is lens, and we can't put anything in front - the picture will be ruined. So, out there exist many forms of lens heater, but it is the pain in the... to wait weeks from eBay to arrive. So, I made this heater in matter of tens of minutes. 7 Resistors, each 1 Ohm, metal film is the best, 1/4 W (1/2 W will be better, but metal film resistors can hold higher temperatures). According to many sellers, usually power is 4W, 0.8A at 5V. So, 5V/0.8A = 6.25 Ohms, but I am using 7 ohms for the sake of longer battery lifetime. In theory, 10 Ah power bank can heat lens for 10 hours or more. More than sufficient for what I need. So far, Sony a6300 battery can hold up to 4h photographing time, with minimized LCD brightness, shooter set to 'silent', and WiFi off. I ordered dummy battery with USB connector for longer recording time, but it not arrived yet.

Near end of the video, captured one late Geminid meteor: https://www.flickr.com/photos/milan_k...
And crop: https://www.flickr.com/photos/milan_k...

Music credit:

Beat Your Competition
Author: Vibe Tracks

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