===== Night Sky Images - 19/09/2021 =====

Very clear skies with almost no cloud cover. Got some great images looking back over the house which I've not tried before. Also experimented a little more with various ISO settings with the same composition as well as wider range of exposure times.

Gear:
  * Canon EOS 200D
  * Tokina AT-X Pro SD 11-16mm f/2.8 (IF) DX
  * Tripod

Weather:
  * Very clear

Location:
  * Garden

Software
  * [[https://www.rawtherapee.com/|Rawtherapee]] - RAW file importing, optical correction & image processing
  * GIMP - RAW/TIF to JPEG, cropping

==== Images ====

These first three images are tests of different exposure lengths, all at the same 800 ISO setting. At 20 seconds the image is relatively clear (though with a relatively modest amount of noise, as expected with a single exposure) with most objects in the centre of the image being well defined and without trails (objects located in the corners will always be slightly elongated on this wide-angle lens):

<imgcaption 1|20s, ISO 800, Processed RAW>{{:blog:photography:night:2021_09_19:img_3208.jpg?650|}}</imgcaption> <imgcaption 1|20s, ISO 800, Unprocessed JPEG>{{:blog:photography:night:2021_09_19:img_3208_raw.jpg?650|}}</imgcaption>

At 25 seconds a moderate amount of objects are starting to elongate slightly:

<imgcaption 1|25s, ISO 800, Processed RAW>{{:blog:photography:night:2021_09_19:img_3209.jpg?650|}}</imgcaption> <imgcaption 1|25s, ISO 800, Unprocessed JPEG>{{:blog:photography:night:2021_09_19:img_3209_raw.jpg?650|}}</imgcaption>

At 30 seconds, I start to get very distinct stair trails forming but quite a significant increase in the number of stars:

<imgcaption 1|30s, ISO 800, Processed RAW>{{:blog:photography:night:2021_09_19:img_3210.jpg?650|}}</imgcaption> <imgcaption 1|30s, ISO 800, Unprocessed JPEG>{{:blog:photography:night:2021_09_19:img_3210_raw.jpg?650|}}</imgcaption>

Looking back in an Easterly direction over our house, showing quite a clear starfield with just a tiny few wisps of cloud:

<imgcaption 1|20s, ISO 1600, Processed RAW>{{:blog:photography:night:2021_09_19:img_3222.jpg?650|}}</imgcaption> <imgcaption 1|20s, ISO 1600, Unprocessed JPEG>{{:blog:photography:night:2021_09_19:img_3222_raw.jpg?650|}}</imgcaption>

**Observation:** //If I want to get more detailed starfield images, then I'm going to have to invest in a star tracker - clearly 25-30 second exposures are just long enough to start forming elongated objects even with my ultra-wide angle Tokina lens. 20 seconds appears to be the sweet spot whilst stationary.//