Beginner's guide to using a DSLR camera and/or GoPro for taking star trail photographs

 The Weather has been pants hasn't it. Everytime there has been a clear night recently, it has always coincided with a full moon; or I have had other pressing family commitments and so haven't been able to get out at night. 

So I am severely curtailing my ambitions for my landscape astrophotography over the next few months. What I would like to walk away with at the end of October is the following:

• a circular star trail landscape photograph of my local church
• similar photo of Windy Cross (A Granite cross and little leat waterfall) on Dartmoor 
• a star trail photo of Rame Head chapel

On the milky way landscape photo front, my ambitions are to obtain by end of October:

• Dartmouth Day mark 
• Start Point Lighthouse
• Rame Head chapel
• Wembury Church
• The Great Mewstone at Wembury Point 
• a better image of Bigbury Island under the milky way alongside one of the huge beach tractor as well

So, to the focus of this blog post. Star trails on a DSLR and/or GoPro. 

Funds are tight. I cannot afford another DSLR body at the moment. My two other cameras are a GoPro Hero 9 and a Sony HX-90 digital compact.  I think the trails will be easier to do on the GoPro, but I am open to that belief being challenged. 

Copyright: Wheal Owles by Simon Torr

So, here are my tips for using your DSLR to gain star trail images:

*source of some information: Peter Zelinka Star Trails tutorial

** I haven't yet shot any star trail images so these are my PLANNED INTENDED settings for future shoots 

Firstly equipment! You will need:

• DSLR
• dummy battery and power bank OR several spare batteries
• Stable tripod with good ball head
• Intervalometer
• wide angle lens - in my case my samyang 14mm. If you want curves - try a 24mm lens, for lines, try 50mm
• Fast SD card - you will need a class 10 UHS class 3 memory card, minimum 32gb - better 64gb

Secondly, what settings do we use? 

1. apply the 300 rule and go for 90% sky coverage in your landscape photo 
2. do one foreground shot at the start or end of your session - so that you can merge it with your stacked star trails in post editing
3. settings:  ISO 1600+ to get lots of stars and dense bright trails; ISO 100 - 800 to get fewer stars and bigger gaps between individual trails with better star colours. In an urban sky - try ISO 400 to 800 at F/4 to F/5.6
4. If light conditions are too bright - reduce ISO and open up the aperture - try F/4
5. shutter speeds - 20 to 30". However, if you use a very low ISO you can increase your shutter speed to 60", 120" or even 180", capturing more light, a cleaner image with less noise and grain. 
6. White balance 3000 - 5200K. I will be probably starting at 3600K. Don't use 'auto'
7. LNR off
8. use an intervalometer. Here it gets tricky. You will either use a 1" delay between your shots or the length of your shutter speed + 1" more. And you need to experiment first before you go out for the night. Peter Zelinka's tutorial really explains it well and you can access it here https://www.peterzelinka.com/startrails
9. I set my intervalometer to take around 3 hrs worth of shots minimum, but that's just me. 
10. set your DSLR to evaluative metering
11. Direction - face north = circles; S = downward arcs; E or W = upward arcs

So what about settings for your GoPro? Mine is a Hero 9

• Night Lapse mode
• FOV - wide
• shutter speed 30" - if in urban environments - then shorten it
• Interval - auto
• ISO 100 - 200 (or 100 min to 800 max)
• If using Protunes - Flat colour and WB of 4000 - 5500K
• shoot in RAW images
• collect 3 - 5 hrs worth of images

Equipment: 

• stable tripod
• spare batteries and/or powerbank and cable
• GoPro camera

Above is an outline of how I go about getting my star trail images. The next step is how to post edit them ad for that I use a program called Starstax.  Having not yet taken any star trails, I won't go into using StarStax until I have used it myself.