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. You can use chemical handwarmer 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.
The Protage lens heater is the one I have, because it was the first one I remember seeing that was USB based. I have a bunch of them. I always carry two with me so I have a spare in case one breaks, because after all they are essentially wires that you wrap around your lens and eventually they could break. I have a bunch of extras to loan to workshop clients.
However the CooWoo lens heater looks interesting, I don’t own one because it came out after I bought mine, but it comes with a temperature regulator. The nice thing about that is you can choose Low, Medium, or High based on your needs. The lower the setting the longer the battery will last. It’s actually slightly cheaper than the Protage so I would give it a whirl, it has good reviews.
I can say that with the Anker PowerCore 10000 battery pack, the Protage lens heaters last about 4-5 hours, and they don’t have any temperature control, so they are at full blast all the time. I also always carry 2 batteries with me in case I’m out long enough to need to switch, or in case one breaks. Right now the Anker batteries I link to below are very cheap, so maybe they are being replaced by another model or something, but they are great batteries. You can also look for a higher capacity battery, Anker makes ones that are higher capacity and so they would last longer. 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.
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