One problem I’ve encountered while doing long time exposure shots outside was lens fogging. As soon as the temperature of the lens drops below the outside temperature moisture condenses on the the glass and you get great  blurry shots. Different solutions range from a soldered ring of resistors up to ready-built solutions which costs quite some money.

My goal was a simple and cheap solution which is easy to handle. Enter USB powered heating soles. For about 5€ they seem to be perfect:

  • You can cut them
  • They are flexible
  • Easy power supply solution thanks to USB

After about two weeks they arrived. I’ve ordered two pairs so I can take apart one and check what’s inside. As expected it’s a simple, rectangular heating foil. Perfect! That makes the cutting very easy.

The power supply is a 15.000 mAh battery pack used for charging mobile phones and so on.

The assembly is quite easy, a rubber band holds the two soles together:


For the battery pack you need a really stylish solution:


All together now:


I’ve tested the setup for the first time in Poland at around -14°C over about four hours. No lens fogging!

Here’s the result:


Conclusion: For 5€ (if you have already the USB battery pack) this solution is definitely perfect. Now I just have to see how it performs in Ireland where the humidity is most likely higher at this time of the year.

  • How to photograph star trails – an introduction | boxxbeidl

    […] 5) Defend your lens against condensation Depending on the weather conditions you might get problems with lens fog. This happens when the temperature of the lens falls below that of the surrounding air. There are commerical products around which range (as usual) from simple & cheap to the luxurious elecric high-end lens warmer. I tried to wrap around a towel which did the trick as well. Make sure you don’t mess up your focussing when doing this as I did. There is a dew point calculator online if you have the needed data. Make sure to take a cloth with you to clean up moisture from your lens if needed. After you have applied your dew combating technology (towel), do a few more test shots and make sure that the focus is still correct. Also make sure that the towel is not hanging in the field of view, which is where the “artistic vignetting” came from. I’ve recently built a simple and easy DIY solution which can be found here. […]

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