Best Sub lengths M42

[drumsolo]

Hi all,

What are peoples views on sub exposure length for the Orion Nebula? I recently took 4 min subs but now realise that was too long because of the bright core. Can I take 4 mins subs and then take shorter ones for the core of say 30 secs and stack them all together? Can different lengths be stacked together in DSS?

Is there an optimal exposure length for this target? I guess a lot depends on how dark the skies are. I live somewhere semi rural with some LP so I use a filter.

Many thanks

Stuart

[ollypenrice]

You really need three sub lengths for M42 in colour imaging. In narrowband you could get away with two. At around F5 I'd suggest 10 seconds, 50 seconds and five minutes, or longer if your LP allows it.

Don't just throw them all into DSS. Make three separate images, co-register them carefully and then follow Mr Lodigruss, whose method is first class...

Compositing 2 Different Exposures via Layer Masks

Mine using this method is here; http://ollypenrice.smugmug.com/Other/Nebulae-and-clusters/i-SnHwq3V/0/X3/NEW-BLUE-STARS-VERSION2B-X3.jpg

Olly

[Earl]

180 seconds worked for me, however I did not Produce an image of the same calibre Olly did

[RikM]

I shot it all at 90sec last year, then processed the image twice, once for the core with a mild stretch and a stronger one for the outer wispy bits. I layered them together using the same technique. I was quite happy with it, but it is also not as good as Olly's.