Moonrise at Knowlton Church Ruins

 Knowlton Church is a ruined Norman church built within a neolithic henge monument. Its a beautiful place a short distance from Wimborne. Supposedly one of the most haunted places in Dorset with stories of a galloping horse and rider as well as a praying nun kneeling within the church.

Andromeda Galaxy M31

It was a moonlit night so I decided to aim the scope in the other direction and chose this beautiful Galaxy. I always shoot deep sky at ISO 1600, normally around 240 seconds but on this night I thought I would change the ISO to 800 and extend the exposure time accordingly.

After a few test shot I decided 6 minutes (360 secs) brought the histogram peak to just past a third of the way along the base line.I normally expose like this at the start of the session.

As the sky gets darker the peak moves slightly back past the third point.






Reducing the ISO value reduces the sensitivity of the sensor and decreases the noise in the image.
As the scope was guiding accurately and the wind was minimal, tracking a star for 6 minutes was easy. After stacking 16 x  6 minute sub together with Flats, Darks and Bias frames there seemed to be more data in the image for stretching. This could be because my camera has been astro modified and has a light pollution filter but I will definitely be using ISO 800 again.