Thread: Milky Way
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Old 26th June 2018
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chris chris is offline
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Re: Milky Way

Originally Posted by Ian View Post
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.

Thanks Ian, I was aware of the 500 rule and as you say, had calculated 15 seconds for my 17mm. Although I am on the lookout for a used 12-40 2.8 pro, so if i get one of those I can be upto 21 seconds at 12mm
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