Stars
No, not a reference to Simply Red - I was never a massive fan, I am of course referring to my latest photography obsession.
One of the drivers for me settling on South Wales for a new home was partly due to an experience a few years back when we stayed in a lodge in the Brecon Beacons, Bannau Brycheiniog. One evening I wandered outside and just looked up for a short time, and as my eyes adjusted to the darkness, slowly the galactic core of the Milky Way started to reveal itself stretching up over my head.
I grabbed my trusty Fujifilm X-T2 camera and, knowing I wanted a fast aperture, put my Fujifilm XF23mm f1.4 lens on it.
23mm is a bit too narrow field of view for astrophotography really, but I sacrificed wide views for lens speed. I fired off a number of shots at f1.4, ISO 1600, and 15 seconds shutter speed (on a tripod obviously) and somehow, I cannot even remember the process I used, cobbled together a few shots similar to the banner photo for this blog and this image.
Back in Kent, I have a friend, Mick, who is heavily into astrophotography. When he was having some IT issues he asked if I could take a look at his setup and I was astonished to see the telescopes he had and the purpose built observatory. My interest was kind of tweaked again but there was nowhere practical for me to put a telescope of any size and the light pollution, although not the worst, was not great. I knew though, that when we did move, I wanted to get into astro as another photographic genre.
Finally, at the end of January 2025, after settling into the new house, I took the plunge and ordered an equatorial mount. It is a Sky-Watcher Star Adventurer GTi from First Light Optics, who I must say were excellent in their assistance in getting me started, especially as I moved from using my camera's telephoto lens to an actual telescope.
An equatorial mount basically tracks the apparent movement of the stars, over long periods of time, allowing for longer shutter speeds to be used which in turn reduces the ISO level required and, therefore, the levels of digital noise in the images.
There is a simple formula for working out the shutter speed you can use for untracked shots before stars start to show movement trails called the 500 rule. You divide 500 by the focal length of your lens (say 25mm for ease) and that gives you the maximum shutter speed you can use before you will start to see trails. 500/25=20 seconds. This is a very rough rule though and you also need to take into consideration any crop factors your camera has (e.g. a 1.5 crop actually makes a 25mm lens the equivalent of a 37.5mm lens and then 500/37.5=13.33 seconds). There are more accurate ways to calculate the exposure time using applications like PhotoPills.
That's all right for you Blacklock
Tina and Hannah pointed out that they also, would like to look at stars and that the whole mount and camera setup up was not the most user-friendly experience for doing so. I agreed, so we added to the equipment fest by buying a proper refractor telescope (and consequently, a whole bunch of other bits of kit so I could hook it up to the camera. I had already splashed out buying a second hand Samyang f2 12mm lens - the only non Fuji lens I own - for when the galactic core starts to make a new appearance in spring.
Enter the Sky-Watcher Evostar ED72 DS-Pro (and a whole bunch of other expensive stuff to make it work with the camera!)
Of course the one thing you can guarantee when you buy a telescope is that you will never see another cloud free sky again! That is not entirely true but not far from it. After initially getting the camera I did have a chance to start familiarizing myself with the process of shooting astrophotography.
The first critical thing you need to learn is how to polar align your mount. Polar aligning basically means making sure your mount is pointing at Polaris, the Pole or North Star. All the other stars appear to rotate around Polaris. The more accurate your polar alignment the better tracking the mount can achieve. Polaris is not exactly in line with an axis drawn from the Earth's South Pole through the North Pole and out towards it. If you pointed your mount directly at Polaris and shot star trails you would in fact see Polaris make a small circle. For this reason the polar scope on the mount, which is used to locate Polaris, has a small clock dial, and an app (there is always an app) can be used to see where on the dial you need to position Polaris.
My first night with the mount was spent trying to master the art of polar alignment.
The next night was spent trying to master the next critical thing, focus. You would think that with the stars being so far away you could just manually focus your lens to infinity and Robert would be your mother's brother. No! This seldom works. You need to use something like live view to zoom in and adjust your focus to make the stars appear as small as possible.
Alternatively, and this is what I have done now, is buy a cheap filter known as a Bahtinov Mask. This causes the stars to create a small star burst effect with a line through the middle which you need to line up exactly on the cross.
The next thing I have to do is set up either a 1, 2 or 3 star alignment. This is something I have not yet had the chance to do but, after polar aligning the mount, you should do a star alignment. The mount has goto functionality which means using its app you can ask it to automatically go to a planet, star, or galaxy. To do this accurately the mount should be told to go to a star and then you need to correct any error in its actual positioning. 2 and 3 star alignments means repeating the process for other stars and improves the mount goto accuracy. The alignment process basically allows the mount to work out exactly where it is pointing to in the sky and then be able to select other targets more accurately.
One thing I could find in the sky without an app was the moon! So far this is the only thing I have been able to shoot using the new telescope and mount.
This was just a single shot at 1/250th ISO 200. The aperture reads as f1.0 because I was using the telescope and not a camera lens. It was also just a quick grab shot between sorting out dinner! Overall I am really pleased with it and looking forward to actually improving on the technique. The normal approach to photographing the moon and planets is to actually take video and select the best frames from the video to stack together and process. It is a technique called 'lucky imaging'. Things like the atmosphere affect the sharpness of any celestial object causing it to shimmer or there may be clouds. Lucky imaging works by taking lots of images (which is why video is often used) and then using software to analyze the sharpest and best images to stack together.
The idea of stacking multiple images is common across all types of astrophotography from planets through to deep sky objects. By shooting multiple images and stacking them together the total exposure time is increased and the stacking process also averages out digital noise. It is not uncommon to see total exposure times of between 5 and 10 hours (one hundred or two hundred 3 minute exposures) for deep sky objects. Sometimes shots are even taken over multiple nights. There are various software packages including, Siril, Deep Sky Stacker, Pixinsight, even Affinity Photo, that can stack the images and then allow you to continue processing them.
What has become apparent during this journey is that different types of astrophotography require different equipment, software and techniques. Well why would't it? Photography in general is an expensive hobby isn't it?
For photographing the Milky Way, you can use a standard DSLR or mirrorless camera with a wide angle lens in the region of 12-16mm. You would not even need an equatorial mount. I have even seen amazing results using an iPhone on a tripod! For planets you are best to get a high magnification telescope (Venus, for example, through my 72mm refractor is very small!) Strangely for deep sky objects, such as galaxies and nebulas, you do not need a long focal length - in fact shorter can be better. Although they are a long way away they are very big! You could shoot something like the Orion nebula, in Orion's Belt, using a relatively small telephone lens (135-200mm) and a DSLR or mirrorless camera. Because these objects need you to gather as much a light as possible though, you really do need a mount so you can shoot much longer exposure times - 30 or 60 seconds up to several minutes.
As always I cannot decide what I want to shoot but I think my main interested will be shooting our own galactic core and deep sky objects.
Although every video tutorial about astrophotography you watch tells you the best way to improve is to get out there and shoot stuff, the abundance of Welsh cloud means I have spent a lot of time trawling YouTube tutorials. It was one such trawl where I found a technique called the 'mineral moon'. The process allows you to draw out the normally unseen colours caused be the different oxides and minerals on the moon's surface. Given I have a picture of the moon, and a lot of cloud, I thought I would give it a go. So, for now, I will leave you with this little gem and leave me wondering if I need a large Newtonian reflector for more planetary work as well!
