Night photography question

Hi all,
I have tried doing star trails several times now and I am getting better at it but can anyone tell me how to stop condensation forming on lens / filter ?
I am shooting in the UK and its around zero at the minute.

Thanks
Andy

Take your gear outside at least an hour ahead of time, so it can cool down to the outside temperature.

and/or use heat packs on the side of the lens/body

I would think that glass is glass. Just like in a telescope. Going from a warm house to the cool night, creates dew on the glass. I have telescopes, and I put them in the garage a couple hours before I plan on using them.

Keep the lens cap on until everything cools down to the outside temp. And do the same when bringing the camera back into a nice warm house. As stated before, condensation is not your friend.

I also have condensation problems in warm weather, very humid in the mountains, and it fogs the lens when I shoot at night.

napawino wrote in post #16560149
Take your gear outside at least an hour ahead of time, so it can cool down to the outside temperature.

All that will do is make the condensation appear sooner.

When an object is colder than the dew point moisture will start to condense on that object. This is commonly a problem when a camera is taken from a cool, air-conditioned, interior into a warm, humid, exterior. The camera (and lens) are colder than the dew point, so moisture condenses on them. Taking the camera outside and letting it warm up (note that - warm up, not cool down) means that it is warmer than the dew point and no moisture.

However, this is not Andy's problem. His problem is that the camera slowly cools down while he's shooting outside. Once the camera cools below the dew point he starts gettting condensation. If it's cold enough then he'll get frost. It is exactly the same process responsible for dew and frost forming on my car's windscreen (and leaving that outside doesn't seem to prevent dew forming).

It's a common problem with telescopes and a common fix is to use a heated dew shield.

hollis_f wrote in post #16563834
However, this is not Andy's problem. His problem is that the camera slowly cools down while he's shooting outside. Once the camera cools below the dew point he starts gettting condensation.

There's nothing like being about the business of shooting, then after a while noticing that the photos are getting soft or foggy. I then shine a flashlight to the front element and see the condensation starting to form. Now I'm done, just when the seeing was improving, or the constellation was rising, or your target was moving to improve the composition with a nice foreground.

Heat packs attached to the lens barrel works for me. If there's dew on the grass or on the vehicles, I attach them before starting the shooting.

Buy one of these heater controllers and one of these straps to suit the size of your lens.

thanks for all your comments.
Frank. you hit the nail on the head because its not an issue for the first couple of hours and then the condensation happens.
ASIGN OBS. thanks for the link. what a cool idea. something else to add to the wish list
cheers all.