50mm 1.8 dew prevention?

[smr]

Hi

I've only used my 50mm 1.8 lens once for astrophotography for a cygnus widefield shot, but that was in the Summer when I didn't need to use dew prevention.

I'm just wondering how to keep the lens from dewing up on a frosty night as where the focus ring would be covered by a dew band or is not a problem ?

[jimjam11]

Something like this:

https://www.amazon.co.uk/COOWOO-Temperature-Regulator-Universal-Telescopic/dp/B07MHGW4DG/ref=mp_s_a_1_1_sspa?keywords=dew+heater&qid=1575986385&smid=A1IYYL3BAMOXNQ&sprefix=dew+&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUFEQlU3OTI0VlJCRE8mZW5jcnlwdGVkSWQ9QTAxODQyNTcxUEJRWFpSUk5GWkFRJmVuY3J5cHRlZEFkSWQ9QTA2MjI4MTExRkFCNTVWWEI1SUNOJndpZGdldE5hbWU9c3BfcGhvbmVfc2VhcmNoX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

 

I wrap it around the lens before focusing and turn the band to focus, it actually helps keep the focus from moving as the non-stm version of the 50mm has a very sloppy focuser...

[happy-kat]

Cheap quick option. Hand warmer rubber banded to lens, I haven't needed to do this yet but it will be the quick approach I'll take after reading about the idea on here.

[smr]

literally just bought that coowoo band the other day so will use that idea thanks. 

I'll be using the 50mm on my HEQ5 Pro so I doubt I'd need to guide.

[smr]

oh a little OT but what aperture should I stop the lens down to to avoid coma ? 

Would f/2.8 be good?

[Alien 13]

10 minutes ago, smr said:

oh a little OT but what aperture should I stop the lens down to to avoid coma ? 

Would f/2.8 be good?

I have the 50mm f/1.8 STM and find f/4 is the best all round option if doing longer tracked exposures however if I am shooting on a fixed tripod with foreground features then using f/2.8 is still fine. In both cases focus about a third of the distance away from the center along an imaginary diagonal for best coma performance.

Alan

Edited December 10, 2019 by Alien 13

[jimjam11]

37 minutes ago, happy-kat said:

Cheap quick option. Hand warmer rubber banded to lens, I haven't needed to do this yet but it will be the quick approach I'll take after reading about the idea on here.

Also tried this and they work well but the proper lens heater is now a lot less hassle (and prob cheaper). I used this approach until the coowoo band included a controller, I have never needed anything other than the lowest setting and my 21ah phone charger seems to run for many hours without issue