Thread: Milky Way
View Single Post
Old 26th June 2018
Ian's Avatar
Ian Ian is offline
Join Date: Jul 2007
Location: Hemel Hempstead, Hertfordshire, UK
Posts: 11,672
Thanks: 427
Thanked 2,554 Times in 1,283 Posts
Likes: 885
Liked 1,766 Times in 797 Posts
Re: Milky Way

Nobody has mentioned the 500 rule. This calculates the maximum exposure time before the Earth's motion starts to turn the star points into little trails. For a 17mm lens you need to double to make 34 (full frame mm equivalent) and then divide 500 by it. Rounding up, that's a maximum of 15 seconds.

Actually, for Micro Four Thirds you can make it the 250 rule and there is no need to compensate for the crop factor, just divide the focal length (17) into 250.

For a 9mm super wide you can expose (250 divided by 9) for 28 seconds.

The longer the exposure the better of course and this is one reason why a moderate wide angle like a 17 isn't ideal for milky way shots, apart from the fact that it doesn't cover enough of the sky.

Founder and editor of:
Olympus UK E-System User Group (
Four Thirds User (
Digital Photography Now (
Olympus camera, lens, and accessory hire (

NEW: My personal BLOG
Reply With Quote
The Following User Liked This Post:
chris (26th June 2018)