One of the most frequently asked questions I get is in regards to lens heaters. Why do you need them? Which one? Which battery?
If you’re shooting when the dew point is going to be near or the same as the ambient temperature, then you should be using a lens heater. This will keep dew from forming on the front of your lens. I have battled with dew myself on a few occasions before I had a lens heater, and it can ruin your night because your images will all be soft/blurry from the dew on your lens!
I recommend electronic lens heaters that connect to a USB battery pack. You can use chemical hand warmer packets wrapped around the lens, but I find these to be unreliable because you don’t know when you’ll get a dud packet, or they won’t burn hot enough, or they’ll burn too hot and die too fast. Plus for the cost of a lens heater and battery or two you’ll easily save money in the long run over continually buying chemical hand warmers.
There are lots of companies now making lens heaters that connect to USB battery packs. The one pictured above by Protage is no longer available but a very similar one is available from Move Shoot Move. That one also comes with a temperature regulator (low, medium, high) so you can control how hot the heater will get. Higher temperature settings use more battery power and vice versa. How hot you need it will depend on the dew point where you’re shooting. I always carry two lens heaters when I’m out at night just in case one breaks.
There are many other lens heaters available on Amazon but I prefer the ones that are a bit skinnier that don’t cover so much of the lens barrel. For example, the CooWoo lens heater is wider than the Move Shoot Move one and will more likely get in the way of focus and/or zoom rings. You do not need a wider heater to keep the front of your lens dew free.
There are tons of USB battery packs available, but Anker is a reputable brand. I can say that with the Anker PowerCore 10000 battery pack, the Protage lens heaters last about 4-5 hours, but they don’t have any temperature control so they are at full blast all the time. So expect similar or better performance out of something like the Move Shoot Move heater that has a temperature control. I also always carry 2 batteries with me in case I’m out long enough to need to switch, or in case one breaks. You can also look for a higher capacity battery, Anker makes ones that are higher capacity and so they would last longer, but I prefer two smaller ones in case one fails. I use Anker because it is a good brand but there are many brands out there. Whatever you get you want at least a 10,000 mAh capacity (hence the name PowerCore 10000 name) otherwise you’ll be changing batteries every hour or two.
Whatever you use, make sure to keep an eye on your battery level and touch the lens heater every once in a while to make sure it’s hot and working. Also, I recommend putting some tape over the blue LED lights on the battery pack, they are BRIGHT, too bright when out in the dark. A few pieces of thin gaffer tape usually dims the lights enough to be tolerable yet still visible enough so you can see them.