November Meeting

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robertofbaycot
Posts: 48
Joined: Mon Jan 30, 2017 7:25 pm

November Meeting

Post by robertofbaycot » Thu Nov 19, 2020 11:07 am

Here are my astronomy pictures from the meeting.
Star trails are built up from 70 pictures.
The night sky is much more colourful than I ever thought!

Star Trails Notes
1 Canon 0X5A4354_e.jpg
1 Canon 0X5A4354_e.jpg (146.16 KiB) Viewed 13 times
#1 single image
70 photos taken using:
Canon EOS 7D Mk II
manual focus
fixed 50 mm lens
f 1.8
20 s exposure - must not be too long or blurs stars
30 s interval
5472 x 3648 pixels

colours enhanced by increasing saturation
- doesn't change hues!
2 Canon 0X5A4354_e_s1.jpg
2 Canon 0X5A4354_e_s1.jpg (95.73 KiB) Viewed 13 times
#2 zoom in to part of preceding
accurate focussing very important - set focus to infinity not good enough!
used LCD monitor with digital zoom for monitor
gives good size picture of single star
manually focus to get diameter as small as possible
hand-held camera means star is moving around rapidly all over the place!
picture shows 3 bright stars, many others & background noise
size of stars probably due to optical resolution of the camera (needs confirming)
3 star trails 2020-08 batch 2.jpg
3 star trails 2020-08 batch 2.jpg (522.72 KiB) Viewed 13 times
#3 star trails from stack of photos
stack of 70 photos used
pictures combined using Maximum option in Affinity Photo
Total or Mean smears out trails & other features
Colours enhanced by increasing saturation
Photos taken in Perseid meteor shower
Quite a lot of meteor trails present
Most obvious vertical on left-hand side
Aircraft track visible 1/4 way down from top
4 star trails 2020-08 batch 2_s1.jpg
4 star trails 2020-08 batch 2_s1.jpg (108.54 KiB) Viewed 13 times
#4 zoom in to see detail & meteor trails
Star trails like corded ropes or strands of wool
Due to exposure (20 s) being less than interval (20s) so get small gaps in observations
All colours as observed - note range blue-white-orange
Physics says there are no green stars!
5 star trails 2020-08 batch 2_s2.jpg
5 star trails 2020-08 batch 2_s2.jpg (236.18 KiB) Viewed 13 times
#5 zoom in to show more colours
red, white purple etc.

robertofbaycot
Posts: 48
Joined: Mon Jan 30, 2017 7:25 pm

Re: November Meeting - Astronomy FITS format

Post by robertofbaycot » Thu Nov 19, 2020 11:16 am

Someone (sorry, forget who!) brought up the problem of using .fits format astronomy images with software such as Photoshop & Affinity Photo. To do this, the .fits images need to be transformed into, say, .tiff or .jpg images.

Free GIMP software seems to be able to do this; Open the .fits file, then Export it in whatever format you need.

GIMP can be downloaded from: https://www.gimp.org/downloads/

Trevor
Posts: 384
Joined: Sun Aug 30, 2009 7:39 pm

Re: November Meeting

Post by Trevor » Thu Nov 19, 2020 1:07 pm

Thanks for the info Robert

Trevor

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