SV172 Dew Heater, Lens Warmer 240mm, Universal for Telescope Camera | Strong Medium Weak 3 Gear Regulator Temperature, USB port, Prevents Lens from Dew, Fog and Condensation for Astrophotography

Well made, works without fail and recommended for value versus the big name brands...

Worked as prescribed.

I woke up at 4am the other morning to view Saturn high in the sky with excellent seeing. I got an awesome view (the seeing conditions were perfect as in the air was perfectly still), but my eyepiece fogged up. I got this heater, and a few days later I got up at 4am again to look at Saturn again. This time the seeing was good but not perfect, but the heater did its job and the eyepiece didn't fog up.

I needed an eyepiece heater to combat the inevitable breathing induced fog that cursed my infrequent viewing nights...I am primarily a visual observer, and I have a few 2" eyepieces that plop into my dob for orgasmic stellar and planetary observations. Recently with the conjunction of Saturn and Jupiter, my target was way low on my horizon and was only getting worse as the days ticked off to the 21st...was out with my wife in early December and we kept breathing on the eyepiece and it was super frustrating, so I researched and bought this thingy. It works well and plugs right into my USB powerpack that I've had for years. This one worked, while another type of heater meant for a more expensive battery setup did not work with my powerpack and an adaptor cord to USB (returning the other one, cause it was just an experiment to see if it would work and it did not warm appreciably). I don't need a dew-not or dewzapper system, when I have something that works very well with my USB pack...you mileage may vary, especially if you intend to use a 12v power supply for other things and justify a $150 power distro system.

I was looking for lower priced dew heaters for my telescope and guidescope. I also wanted usb powered since I do not have a dedicated 12v system for managing dew heaters. For the price I went ahead and tried these and so far they have worked well on my Sharpstar 61 and Ioptron guide scope. I’m using them from a usb power bank and with the 3 adjustable power options they have worked fine for my environment. I’m in Texas so it hasn’t gotten really cold yet, but they work well in the current autumn weather. If you want a less expensive usb powered option, I would recommend these. Do make sure to measure your scope or lens and compare to the length of the heating element of the heater.