USB Lens Warmer, Lens Dew Heater Strip with Temperature Regulator, Condensation Prevention for Telescopes Camera DSLR Lens Telescope Eyepieces Less Than 3.15 inch (80mm) in Diameter

Astronomy. New to the hobby... and I am so glad these work as well as they do;-) Anyone who stares through a telescope on a winter night would understand. No drama, just plug it in and does the job nicely. Comes with a nice bag (some don't, I have others), has a nice cord that is easy to manage when cold. And the cord has been long enough to work fine for my needs (8"dob with a battery at it's base). I leave it on all night. In the beginning I checked the temperature regularly but now have just settled in to taking it for granted (sigh of relief)

This warmer did a fine job on a cold fall evening that was quite humid. The low setting kept condensation off my 200mm canon lens for a 2 hr astro-photography session. The cord is a little short so I recommend getting a long usb cable. Since the usb carriies the power, you don't need to worry about cable length like you would for data transmission. I got a usb wall charging port and 15 foot cable to reach the outlet on the back of the house.

Did the job as described

This lens warmer is easy to use and it seems to work well. However, you need to check it during use to make sure your lens is getting enough heat. Probably won't overheat any lens.

I used this USB powered Dew Heater on a 8mm lens for night sky photography, an it kept few from forming on a humid night with temps in the 60s. It heats quickly on the High setting, but Low is recommended for my conditions. I used a 20,000mah portable power supply for over 2 hours continuously without any problems. This power supply has 10W USB-A output, so it has no problem running the heater. I didn't try to measure current, but I did plug it into an old phone charger that has a LED on it, and this heater apparently needed more power than its stated 5v 1000ma (5W) output because the light constantly switching between dim and bright. That tells me that a small, lightweight USB battery probably cannot run this thing, and that may be something you need to consider before heading out for a long photo session.

I use this when doing nightscape photography and it does a great job of keeping the dew from forming on my lens. It has low, medium and high settings and so far I’ve only had to use medium. I power it with a usb battery bank. (Not included) Comes with a pouch that’s perfect for storing hit and the battery together.

Keeps the lens warm like it should

It took two of these to reach around a 5 inch diameter telescope. The blue LED lights on the controller are VERY bright and perhaps a bit too bright for nighttime visual astronomy. Some electrical tape over the lights helps solve that issue.

The instruction print is a bit small. To turn on hold the button for about two seconds. What's nice: it's long, and it comes in a nice pouch. Con: It may be just me, but I prefer my cables to be modular, this isn't.

This thing just about set my guide scope on fire. If I hadn't been there at the right moment, law suite. As it was it burnt my finger just removing it from the scope.

pourrait chauffer un peu plus ..........

The switch is barely just function as on and off and its broken after one use though warmer works