Just a little timeline chronicling my astrophotography dabblings so far.
I bought my first telescope! I opted for the Astronomers Without Borders Onesky – a collapsible 130mm (5in) reflector. I opted for this telescope because:
I also bought a celestron kit w/ a variety of eyepieces, a 2x barlow, and a T2 adapter + 1.25” adapter for my Sony A7S II. This camera is not ideal for astrophotography, really, despite its low light performance. It has a large full-frame sensor and relatively few pixels, making for a general lack of detail in tiny objects through a telescope.
My first night I took it out to my parents’ place in Castillian Springs, where they live on a hill with unobstructed skies and much less light pollution. Spent some time getting acquainted with visual scoping, but didn’t have much luck with photography: I had trouble getting the focal point of the telescope on to my camera’s sensor – i.e. I couldn’t quite focus to infinity.
Skip forward a week, and I realized I could unscrew the barlow lens from its barrel and screw directly into the 1.25” adapter threads, which allowed me to give prime focus photography a try. Success! My first photo of jupiter and its moons, with uh … minimal (aka terrible) processing:
The following morning with fresh eyes I took a stab at reprocessing it with much better result – in this you can see all four moons! Barely!
Took my first stab at Saturn:
Not amazing, but definitely Saturn! The moon was rising late that night, so I gave that a whirl, with pretty good results:
On this night I also experimented with eyepiece projection – a different method of photography where you use an eyepiece and barlow in between the telescope and the camera to “project” the image from the eyepiece onto your camera sensor. I didn’t have much luck with this, unsurprisingly, as between the adapters involved and the small eyepiece lenses, the light actually reaching my camera was cut to nearly nothing. This explains why eyepiece projection is generally regarded poorly by most astrophotographers. Live and learn!
I ordered a 3X barlow, hoping to get a bit more detail from Saturn:
Not bad: bigger, but not much detail.
My first attempt at stacking!
This actually (surprisingly) worked quite well! This is a method where you take a video and use image stacking software to analyze the frames, discard the poor/blurry frames, and combine the remaining frames – generally for a boost in detail and reduction in noise. I didn’t have a lot to work with, because Saturn was projected as a very small dot on my sensor. Nonetheless it was able to pull out a decent amount of detail!
Emboldened by the success with Saturn, I gave Jupiter a try, with the 3x Barlow – tracking manually with the 3X barlow is pretty challenging, but I managed to get it in the frame long enough to take a few videos and stack them:
Not bad! I had some weird issues with banding at first, which I alleviated by tweaking the color detection in Autostakkert. I am not entirely sure why I lost all the color in stacking, but it’s probably because there just wasn’t much color to begin with.
Here’s something fun: around 10 years ago, my family went to Cape San Blas, FL for a week. I was just getting into photography – I had a Canon 20D, a wide angle lens, and no idea what I was doing. But the views of the Milky Way from the beach were spectacular. I tried taking some long exposures, but between the noise of my relatively old crop sensor and the heat, the results were riddled with noise and hot pixels. I gave up and never posted any of the shots I got that night.
Skip forward ten years, and here I am playing with astrophotography and learning all about image stacking. It occurred to me I might be able to salvage the original data. I had the 10 original raw images and I gave it a whirl. I was stunned by the results!
On the left is an example of an uncorrected frame I got that night. On the right, the result of stacking & cleaning up. Modern software is pretty cool.
Another attempt at moon photography. It’s been rainy/cloudy all week, but there was a brief moment of clear skies before some storms moved in.
I played around with stacking/processing the photos of the moon with both PIPP/autostakkert and Pixinsight. Pixinsight, from what I can tell, is not really designed for planetary imaging, but I wanted to learn the tool and it was an easy place to start:
You can see that there’s some weird fringing/ringing around the moon in the pixinsight version – still a lot of learning to do with that tool, but not a bad start!
I got my first equatorial tracker mount! I don’t want to spend a ton of money before I have to (cough cough in theory cough), so I bought one of these – it’s a tiny little DIY type equatorial tracker. I had tested it out on a cloudy day and verified it mostly worked, even though I couldn’t see Polaris to align it very well. Last night the skies were clear for the first time in weeks, so despite the Very Bright Moon, I gave it a whirl in the opposite direction. Since I was mostly just testing the functionality of the tracker, I used a Jupiter-9 85mm – partially because it’s relatively light, fast and long, and partially because I was morbidly curious how bad it’d look (narrator voice: very bad).
I just pointed it randomly in the sky away from the moon, so nothing of note necessarily – but astronometry knows what it is. So as you can see there’s quite a bit of light pollution and noise, but still: the center stars are (mostly) stable! The stars on the periphery suffer badly from coma, due to my poor choice in lenses. This was my first chance to learn more about processing photos as well: specifically, the value in using flat frames to correct for lens vignetting/fall-off (in addition to dark frames) when stacking. Not particularly amazing results, but good confirmation that the gear works and some processing experience under my belt!
A day of unexpected success! I hadn’t planned on doing any shooting tonight, but the skies were remarkably clear, so I gave it a whirl. First I wanted to try my equatorial tracker again, with the goal of producing a basic wide starfield free of as much noise as can be expected in the city. I’d previously been having a lot of trouble with post-processing. Specifically, my flats were overcorrecting the final stacked image. This time around, I shot the flats outside by putting a white t-shirt over my hood and aiming a diffuse LED flashlight at it. Still not ideal, but it yielded much better results. No overcorrection!
Still nothing amazing – I just pointed the camera straight up and away from the rising moon, so that’s Vega on the left completely blown out. Still some trailing, of course, because my polar alignment wasn’t quite perfect. Still, encouraging results.
After this, the moon rose, making any further starfield attempts kinda pointless, so I figured I’d try to get Mars (so far my white whale) again. I’ve had a lot of trouble with Mars – never getting much beyond an overexposed blur. I think it’s just so bright I kept consistently over-exposing it. I made an effort this time to expose it properly and had some moderate success for a change! First, I stacked the entire wide field w/ Mars in DeepSkyStacker so I was able to get a shot cropped with some stars around it:
I then used PIPP and Autostakkert to stack just the planet itself. Pretty blurry but you can see a tiny bit of detail and, if you squint and really believe, the polar ice cap on the bottom.
I got a new mount! Despite my intentions to not go overboard and spend a ton of money, I decided to go ahead and go overboard and spend a ton of money. I got a Skywatcher EQ6-R Pro mount. Why? In the pantheon of Things You Can Buy For Astrophotography (which I am learning every day is bigger than I thought), the mount you use seems to be what everyone recommends to start with. In addition to equatorial tracking, it can also do go-to navigation for telling it what to point at (after some alignment/calibration), and allows for fairly heavy loads (with a capacity far exceeding anything I’ll be using short-term with my camera or Onesky 130). The EQ6-R Pro is a newer and very well-regarded mount that comes highly recommended – and if I get bored of the hobby, it should hold its value and be pretty easy to sell. “Mount first” is a mantra I hear from a lot of people, because I think stability and tracking are paramount over anything else, so I decided to get the mount and learn how to use it before deciding if/how I want to proceed upgrading the telescope and other parts of the optical train.
Tonight I did a test-run of the setup/teardown and polar alignment on my deck (seen above along with my assistant Emma The Dog). It was not easy (more on that later), but it worked. I was able to point my telescope at Saturn and leave it tracking as long as I needed. I took some shots and stacked – probably the best result I’ve had for Saturn so far:
You can see the cassini division in this one, at least! At this point, the limiting factor for planetary photos is clearly optical – the collimation of my telescope and the tilt (the weight of my camera pulls it and the focusing ring away from the focal plane a bit) combined are reducing my ability to get shots with better focus. This may be improved if I collimate better, but probably it’s not going to get much better without a different telescope better suited to photography. I did also manage to point the telescope at Andromeda, M15 and a few other things, but I won’t humiliate myself from posting the photos I attempted from the city, since the sodium vapor lamps near my house mostly stole the show.
This Labor Day weekend my parents hosted a family get-together for some birthdays. I decided to take the opportunity to haul the new mount and telescope out to their place, since they live in Castillian Springs, TN – which, while not perfectly dark still has far less light pollution. I setup the mount early in the evening before dinner while we waited for it to get dark:
(Warning: boring ranting about mount polar alignment and goto tracking to follow – skip ahead to avoid.)
So. Getting this mount aligned was a bit of an ordeal. I spent about 3 hours trying it over, and over and over. Sweat pouring down my face, making treks back/forth to the house to watch tutorial after tutorial on youtube. I could find no fault with the polar alignment, but when I attempted the initial alignment (with 1, 2, or 3 stars), it simply didn’t seem to be working: I’d pick Vega as the first star, and it would slew to a point way off-target from where Vega was. At one point I even thought I had accidentally aligned it with a star other than Polaris and went out into the dark to do some old-fashioned star chart/constellation navigation to make sure I actually had it pointed it at Polaris, which I did. In the end, when I was about to give up, I decided to just power through the 3-star alignment and manually slew the telescope to where the star should be. Et voila, it worked fine after that. What I realize now is that I think I was expecting a bit too much of the hand controller’s initial alignment star acquisition. I thought something was wrong because it wasn’t anywhere near Vega, when in reality that’s just how it goes (and why many people opt to use a computer and eqmod over the hand controller).
I’ve also learned the extent to which polar alignment is separate/different from star alignment. If the mount is aligned at the North Celestial Pole via polaris, the equatorial tracking will work, period, regardless of anything else. Aligning the go-to functionality by initial stars is, conversely, entirely relative based on your location, elevation, and time, so it makes perfect sense that the first-pass before alignment is not going to be great.
Anyway, tl;dr: I got it working.
It was about midnight by the time I finally got goto working, so I didn’t have a ton of time. I pointed it at Andromeda first and took some lights, darks and improvised flats (paper towel and LED headlamp) with my telescope, some wide-angle 10mm shots of the milkyway with my camera, and some 200mm shots near IC59 (basically just stars). I didn’t bring a computer with me, so all processing of the data would have to wait for the next day.
This was my first time trying stacking with data actually much more sensitive to flat/dark calibration and noise, and it was a good test to isolate some weaknesses in my gear for this stuff. To start with, I dumped the shots of andromeda into DeepSkyStacker (vs Pixinsight, because I am still learning it and wanted a quick test), and could see that for some reason adding the dark frames basically ruined the photo:
I’m still not entirely sure what went wrong, but after some deliberation with people in the /r/astrophotography discord, it seems likely that the issue is with the data and conversion from my Sony’s raw format to TIF. Sony’s raw format is not supported by either Pixinsight or DeepSkyStacker, so for this processing I had been converting to uncompressed (in theory) 32-bit TIF from Darktable and using that as source data in pixinsight and Deepskystacker. There’s no way of knowing what darktable is actually doing – someone in the discord channel said the supposedly uncompressed TIF seemed to still have bad compression artifacts. I was able to salvage the data into semi-presentable photos by just not using the dark frames. The conclusion I’ve reached is that for future attempts, I am going to use the Sony compressed RAW format, which pixinsight does actually support, and should hopefully yield much better results.
The good news is the mount performed admirably. From the shots I took (most at 30”), there didn’t appear to be much trailing. I suspect anything much beyond 30” would have started trailing a bit (based on some subtle drift I could see from frame to frame), but once I tackle the mount’s periodic error correction, I expect it to do quite well.
You really don’t appreciate how big andromeda is until you get it into view. Why didn’t I turn the axis of the camera so the horizontal sensor was in line with the plane of the galaxy? I don’t know!
Sadly I had no flats for the milkyway. I was able to improvise flats for the telescope and 200mm shots with a paper towel and LED, but this lens’s hood is so short there was just no way. Thus, quite a bit of dust spots evident. Clean your gear, kids. Flats would have also corrected the pretty severe light fall-off. I’ll have to figure out some sort of softbox contraption or just get better at doing them during the day w/ the sun.
This photo is not particularly impressive since it has no subject per se, but it shows pretty clearly that there was little to no trailing and that the 200mm is pretty impressive for this sort of thing – no visible coma in the corners at all. I wish now I had pointed it at andromeda instead of or in addition to using the telescope – I think it would have come out nicely, despite being a wider field of view (turns out Andromeda is huge).
Brief update: practiced setting up and tearing down the mount on my deck last night. I think I’ve got it down, at this point – was able to get it polar aligned and goto aligned in about 10 mins. Pointed it at andromeda with my camera + 200mm just to see what I could get. Despite the light pollution at my house, still came out pretty well! I think switching to compressed raw helped quite a bit.
Had some trouble with the pixinsight preprocessbatch script – it was complaining about inability to find stars. I’m not certain if it’s the light pollution or underexposure, but DSS had no trouble with it.
Minor update – turd-polishing edition. Clouds have rolled in, so I’m left to reprocess old data and hopefully learn some things. I took another stab at Andromeda from yesterday in Pixinsight this time. Everything worked pretty well and I was able to pull out a bit more detail, but I’m still stymied by the gradient from the plague of sodium-vapor streetlamps flanking my house. I feel like PI has a tool that can remove this, but I am not sure what it is yet.
The clouds have parted! After a week of heavy clouds, we finally had some clear skies last night. I might get lucky and have a few more days this weekend, too, despite the barrage of hurricanes currently off the coast. I setup the mount last night and decided to play with using just my camera, the Canon 200mm/2.8 and a Tamron 2X teleconverter. I knew the TC is not particularly great, but I was hoping the optical compromises would be worth the 400mm focal length and that I might be able to get some interesting stuff.
First attempt was M13 – it came out okay, all things considered. The TC added some horrendous coma in the corners, but I knew most of these targets would be in the center of the frame, so it looked okay. The good news is: I figured out how to fix the light pollution gradient! Turns out the Pixinsight tool I’ve been looking for is DynamicBackgroundExtraction (DBE). It lets you sample points along an image (avoiding actual data/stars) and develops a gradient that you can then subtract or divide from the master image. It worked great!
Next I tried Andromeda again because … why not. I’m sure it will be a frequent subject. This turned out okay, all things considered – not a lot of color or detail, but that’s to be expected given all the light pollution and the amount of glass it’s going through (including the cheap teleconverter). Still, glad I got a result without the awful gradient.
Lastly I picked an arbitrary target before bed – the Triangulum Galaxy (M33). I thought this would be a long-shot, because I could hardly see anything in the test shots, but it turned out pretty well! I cheated and used the same darks, flats and offsets I took for andromeda since nothing else had changed, and I didn’t notice any detrimental effect – although there’s still some dust spots that weren’t eliminated by the flats. I’m not 100% certain why, but I should probably just clean my shit, really.
I was pleased to get a bit of color in this, and impressed that I got any detail in the galaxy at all – probably owing to its location high in the sky, so I was cutting through less atmosphere (and less glare from streetlight pollution).
All in all a pretty successful night – looking forward to having a chance to set this stuff up in some darker skies. I’m still deliberating on what path I want to choose for upgrading my optics – for now I am still enjoying learning how to use the mount and the processing tools. There are so many options to choose from between reflectors, refractors, etc – I’m still feeling out what I think the best path is. Using the AWB OneSky has somewhat lost its allure because it’s a tremendous pain to use (and obtain focus with), compared to the simplicity of mounting the camera + lens itself. But, I’m trying not to let this color my decision, since obviously the AWB OneSky is about as far as you can get from a telescope designed for imaging, and I know that better refractor setups are not without their annoyances (e.g. sensitivity to temp/conditions, etc).
Friday night – you know what that means: astrophotography, wooooo party. I took delivery today of a 72mm light pollution filter I bought on a whim for my Canon 200mm/2.8. There wasn’t much research that went into this purchase: it was simply the only filter I could find that’d fit my lens. It claims it filters out 570-610 nm so I decided to give it a whirl. First, though, I setup my telescope and attempted to get prime focus (without the use of a barlow). I succeeded but gave up pretty quickly on any attempts at photography for the simple reason that there are two or three mega-bright sodium vapor lamps blaring into my yard, and while the OneSky 130 is good at a lot of things, blocking incidental light is not one of them. Since it’s collapsible, half of the telescope is exposed (just 2 tubes), which is not a problem in dark skies, but in the city, it’s a massive opening for light/glare. I used it to align the mount (which I’ve gotten down to a relatively quick process now, fortunately), and took it off and just rolled with my camera.
First target was the Dumbbell Nebula (M27) simply because it was high in the sky. It came out pretty well! This is my first attempt actually picking up any nebulosity from anything with color, so that feels pretty good.
Next I tried Andromeda again because why not. I still struggle with processing Andromeda – DBE seems to work splendidly on other more remote targets, but Andromeda’s size means I was constantly struggling between eliminating the background noise and losing detail in the galaxy itself. I am hoping this will be a non-issue when I try again from darker skies. Additionally, I might have better luck if I waited till it was higher in the sky. Nonetheless this is still the best results I’ve gotten of Andromeda – and not bad considering I’m shooting from the middle of a white-zone urban area.
By this point I was getting tired and running out of ideas, so I just pointed at M33 again, to see if the light pollution filter yielded better results than the previous attempt. It came out okay – slightly better than my first attempt, though I think that’s owed more to my skill with postprocessing improving than any improvement in the actual data.
It was around this time that I noticed the Pleiades had risen – which around here is a sure sign you should be in bed. Because I prefer to make bad decisions, I tried to photograph that as well. It seemed to be turning out okay, but postprocessing attempts fell apart due to some sort of data corruption. I am not really sure what the issue was (something with my darks and/or offsets, I think), but it was segfaulting Pixinsight and DeepSkyStacker both. I managed to coax DSS to actually stack them somehow, but the whole thing was kindof a mess and I wound up with some sort of green tinge (in stark contrast to the normal stunning blue through the nebulous gas in the foreground you usually see). Oh well, next time!