Orpington Astronomical Society

Astronomy => Astrophotography => Topic started by: MarkS on Aug 10, 2016, 22:25:17

Title: Trifid, Lagoon etc. Work in Progress
Post by: MarkS on Aug 10, 2016, 22:25:17
My first deep sky image for months!

The Trifid, Lagoon and other friends from Saturday night.  H-alpha modified Sony A7S on Tak Epsilon 180ED. 50min total exposure time as 100x 30sec subs at ISO 2000.

(http://www.markshelley.co.uk/Astronomy/2016/lagoon_trifid_06082016_small.jpg)

Stars are a bit squiffy at the top right so something obviously needs fixing :(

Larger version here:
http://www.markshelley.co.uk/Astronomy/2016/lagoon_trifid_06082016.jpg

Enjoy!

Mark
Title: Re: Trifid, Lagoon etc. Work in Progress
Post by: Carole on Aug 11, 2016, 09:20:34
Wow, that's an even bigger FOV than I got down at Ollys with his Atik1100 &  Takahashi FSQ106N - and yours shows more detail.  Mine were 600sec subs and yours are only 30sec subs. 

That's one amazing camera the Sony A7S, and I see Peter Shah is starting to use this camera too.

Carole
Title: Re: Trifid, Lagoon etc. Work in Progress
Post by: MarkS on Aug 11, 2016, 19:12:25
Quote from: Carole
Wow, that's an even bigger FOV than I got down at Ollys with his Atik1100 &  Takahashi FSQ106N - and yours shows more detail.  Mine were 600sec subs and yours are only 30sec subs. 

That's one amazing camera the Sony A7S, and I see Peter Shah is starting to use this camera too.

Carole

Yes, it's a very interesting comparison with yours: http://forum.orpington-astronomy.org.uk/index.php?topic=9223

I've got a slightly larger field of view.  My total integration time is 50min whilst yours is 270min.  I don't need long subs because the sensor read noise is so low.  However the wider aperture (180mm vs 106mm) of the Tak Epsilon means I am collecting 2.6x as much light (once my central obstruction is taken into account).

The QE (quantum efficiency) of the A7S is estimated as 65% whereas the KAF-11000 is 50%.  The Sony certainly seems to be giving cooled mono CCD a run for its money!   I always thought it would.

I'm sure Olly's sky is much darker - mine was giving an SQM reading of 20.8-20.9 that night.

Mark
Title: Re: Trifid, Lagoon etc. Work in Progress
Post by: JohnP on Aug 12, 2016, 07:55:20
That's pretty darn impressive Mark for such short acquisition. Out of interest do you know what causes the brightness down LHS - I presume another astronomical object near by - also evident in Carole's image.

Top marks though - John
Title: Re: Trifid, Lagoon etc. Work in Progress
Post by: Fay on Aug 12, 2016, 17:44:06
Great picture Mark, such an interesting area

Fay