USB Lens Warmer, Lens Defogging Heater Condensation Prevention Lens Warmer, Fast Warming for Universal Camera Lens,Telescopes,Coffee Cup,Baby's Bottle

Does the job. I take pictures or the night sky. Dew is a problem. I used this on a small telescope also (70mm refractor) and it’s just big enough. I attach it to a small USB power bank.

Too small for a lens heater and the cable is too short, but works really well for a spot heating pad.

It works get on telephoto lens. 18-55, 70-200. It's a little wide for shorter fixed lens. Does the job! I like it.

This worked this past Christmas up in Fairbanks Alaska in -50 degrees below zero. Lens did not fog or ice up while out taking photos.

This little thing works just fine. Has some frosty nights of astrophotography and this kept the lens nice and clear. It seems to draw current just fine from a usb port or usb charger. Also put on my 102mm telescope. I think that might be the max diameter that it will fully wrap around.

I haven't tested outdoors in the cold but I placed a Casio watch with thermometer and after about 10 minutes it reads over 125F. I don't see why this shouldn't work to warm a coffee mug on a long trip. I also own a 6" telescope, although it may not wrap around it I will give it a try as dew heater. Oh BTW, also works for my tennis elbow pain. Excellent!

Keeps lens warm. Only good for short lenses. If place on long lenses, cannot manipulate the zoom and focus.

I use this on various canon lenses and an Evostar 72ED telescope. I never have problems with dew.