OK, DITCH Your Lens Hoods...

[ameerat42]

... but only "sometimes" :eek:

This is an article I saw somewhere else, and the author explains it in the video:
https://www.shutterbug.com/content/surprise-lens-hoods-can-ruin-cold-weather-photos-video

He's saying that in some cold weather situations a lens hood can significantly soften images.
The salient point is about 3:30 into the video, but it's only a bit over 4 mins long.

- And don't forget where you tossed your lens hoods :p

[Toddyh]

Interesting AM. I wonder if it's specifically a long lens issue or if us landscapers will come across this too.

[Tannin]

Good point to raise, AM. However they key here isn't the lens hood, it is shooting with your equipment at a very different temperature to the environmental temperature. You get a similar (actually even more crippling) issue when you do the reverse. Sit in your nice, cool air-conditioned hotel room (or car) for some hours. Then step out into some tropical heat and humidity. Zap! Your lens fogs up. You can't even wipe it clean because it fogs up inside and out. The only cure is to let the lens warm up to around about environmental temperature.

(Whether that general rule - have the kit at about the same temperature as the air - is applicable at the never-seen-here temperatures this chap is shooting at I don't know. I imagine that, all else aside, you have to keep the batteries warm.)

Anyway, good point to know about and remember.

[nardes]

On my telescopes, where there are optics exposed to the atmosphere, as the temperature drops during the night the optics can begin to dew up, even with a dew shield fitted.:(

To prevent this, there are astro-dew heaters (https://www.bintel.com.au/product/kendrick-premier-heaters/) which are low power heaters that fit around the outside of the lens cell (within a Velcro strap) and keep the optics just 1 degree or so above the ambient air temperature and this prevents dew from forming, but does not heat the optics enough to cause thermals, which would distort the incoming light.:)

Cheers

Dennis

[torro]

I agree, the same when doing the opposite. Eg warm to cool temperatures. Found this when we cruised to Antarctica.