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

I've used this lens warmer many times during cold and warm humid nights while doing night sky time lapse photography. It has performed flawlessly, keeping the lens clear for hours when conditions were such that the lens would have been rendered unusable within the first hour. I won't be without it during nighttime photography now.

I waited a while to write this to make sure I put it through its paces first. It works and does great. It makes a huge difference when doing any night shooting. This is an extremely useful piece of kit that has earned its spot in my small bag (an accomplishment for me).

I bought a previous version which has worked well for three years. This has a new controller and I can't get it to reliably turn on, the lights indicating power do not reliable respond?Edit : although similar in appearance, this controller is different in function. Finally read the new directions (press and hold the on button for two seconds) and got it to work.

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.

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)

Barely used on low 2 times. on the second use i started to smell something burning. Go over to my astrorig and this warmer is absolutely terrible. It was set to low and it started to heat up to the point it started to melt part of my camera lens. Now this $20 item has to be replaced as well as my $400 Rokinon 135mm Lens and yet this company has not gotten back to me about this issue nor will they even offer a refund STAY AWAY IF YOU LIKE YOUR CAMERA GEAR AND POSSIBLY YOUR HOUSE

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.

Lo recomiendo. Vivo en Florida, la humedad es muy alta y a veces el lente se empaña y tarda mucho en volver a la normalidad; pero esta cinta eléctrica actúa rápido.