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I apologise in advance for the long post!

Hello, I would appreciate some advice and perspective on finding the most cost-efficient way of optimizing my current astrophotography setup. I am in no hurry to upgrade as I have yet to push my current equipment to its limits, but I feel like I need a sort of long-term plan and sense of direction to keep myself from getting the "shiny new object syndrome" and compulsively browsing FLO whenever I see nice pictures.

My first year of astrophotography was with an unmodified pentax K-S1, a tripod, a 50mm lens and very cold hands since the camera did not support a wired intervalometer. With that equipment I was able to capture the M81 and M82, the orion region and andromeda. Buying a skywatcher star adventurer was a massive upgrade, together with a 200mm lens it opened the way for galaxies like M101 and closer views of the pleiades, orion and andromeda.

A few months ago I bought a modified Canon 100D, an intervalometer (finally), a vintage 135mm lens (which suffers from less aberrations than the aforementioned 200mm) and an optolong l-enhance. This has allowed me to shoot targets such as the California, Heart and Soul nebulae even from urban skies (bortle 6) with a full moon. I am sitting on a few nights' worth of unprocessed data because processing is time consuming and studying takes up most of my time. I purchased a Startools license so I think I'm covered from that point of view, even though I plan on checking out the free trials of Pixinsight and APP once I acquire more (and better) data.

 

I find myself unsatisfied with the results I can produce and lately I've done a lot of research into the manifold possible paths of improvement.  I am set on sticking with the star adventurer as it allows me to set up very quickly and it fits nicely in my backpack when visiting darker skies. I have no plans to purchase a full-on equatorial mount as I wouldn't be able to carry it back and forth. Here are some key points I have noted down:

  • A faster and sharper lens such as the Samyang 135 f/2 would allow me to acquire better data much faster, but I feel it would be a temporary band-aid as there are many targets which are rather small at this focal length therefore
  • A long telephoto or a short telescope would enable me to get more details out of big targets and allow me to image smaller nebulae, however guiding would very likely be required (about 500-800€ for the telescope and €250 for guiding)
  • Selling my current equipment and buying a used mono camera + some filters would be expensive (I believe no less than €800 more than what I could make reselling some items and possibly a kidney), but I am very fascinated with the aesthetics of SHO pictures and it seems suited to a 135mm lens. Is a star adventurer even precise enough for narrowband imaging (considering the need for longer subs)? I suppose guiding would be a mandatory requirement.
  • This one is probably a bit gimmicky: selling my current camera and buying an ASI533MC + Evoguide 50 with a flattener, the difference would be similar to the price of a Redcat but I would get the added bonus of cooling I guess? Not convinced about this one.
  • I own another DSLR for daytime photography so in theory I could go frankenstein on the canon to try and cool it or debayer it, but I am not sure I'm willing to accept the risk of messing up and rendering it useless.

 

I thank you in advance if you've had the patience to read through the whole post, I would be grateful for any input and opinions concerning the points I have brought up or your own experience with this hobby.

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Have a wade through the very long star adventure thread to see members using different devices and guiding.

The biggest immediate gain I think will come with post processing skills, and ensuring your stacking with calibration frames makes the most of your captured lights. StarTools with DSS is your software covered. 

I don't have direct experience to comment on mono, or guiding etc.

Edited by happy-kat
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6 hours ago, rickwayne said:

What dissatisfies you with what you're producing now? That would inform any practice, gear, or software recommendations I could make. Trailed stars e.g. leads to different advice than noisy images.

I would like to take pictures of better quality where the background is smooth and fine detail is well defined when zooming in, something that would look good as a wallpaper or maybe even printed. I am aware that processing is absolutely key, but I don't think I can acquire data that is  sufficiently clean and sharp to get the sort of results I have in mind. 

Another concern is maximising the opportunities to shoot, the amount of data I can gather (faster optics basically?) and the number of targets that I can frame up nicely (longer focal length?). 

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Of course the knee-jerk answer to noise is always "more integration time", but you knew  that.

You can quantitatively analyze your images to see what might be most economically improved. Noise? Faster optics, as you say, or longer total integration time. Detail? Have a look at the full-width half-maximum numbers for the stars in your images, and their eccentricity.  That will tell you if focusing aids, better optics, or more attention to polar alignment and/or autoguiding might pay off the best.

It also pays to be aware of your image scale -- how much  of the sky is represented by each pixel. My K5-iis DSLR, for example,  is somewhat  undersampled  for my Stellarvue, meaning that the pixels  are a little too big for optimal  detail. That's one reason I selected the ASI183, which has much smaller pixels. Good primer and calculator for that here.

I guess you  could say I've had success with 30-second unguided NB exposures with a mono camera (guiding wasn't working that evening). No APOD, but it's recognizable. This is on a CEM25P mount which has a factory guarantee of +/- 10" periodic error or less, at 362mm F/L and F/5 or thereabouts.

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On 24/12/2020 at 01:19, rickwayne said:

You can quantitatively analyze your images to see what might be most economically improved.

It also pays to be aware of your image scale -- how much  of the sky is represented by each pixel. My K5-iis DSLR, for example,  is somewhat  undersampled  for my Stellarvue, meaning that the pixels  are a little too big for optimal  detail. That's one reason I selected the ASI183, which has much smaller pixels. Good primer and calculator for that here.

For now a raspberry pi running astroberry seems like a cheap solution to many problems, it should help with consistent focusing, faster framing and dithering to get rid of walking noise. I thought that stacking lights from multiple nights with slightly different framing would be akin to dithering but it doesn't seem to solve the problem.

On 24/12/2020 at 01:19, rickwayne said:

It also pays to be aware of your image scale -- how much  of the sky is represented by each pixel. My K5-iis DSLR, for example,  is somewhat  undersampled  for my Stellarvue, meaning that the pixels  are a little too big for optimal  detail. That's one reason I selected the ASI183, which has much smaller pixels. Good primer and calculator for that here.

Undersampling seems unavoidable with a DSLR and the focal lengths I'm imaging at. But I will keep it in mind if I decide to upgrade the camera.

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Heartily concur that a computer for acquisition is a real force multiplier. Plate solving obviates searching for targets. Quantitative focusing metrics, even absent robotic drive for the focus, means fewer tossed subs and getting to "go" more quickly. Analyzing your images in real time for focus, star eccentricity, proper exposure, and more lets you deal with problems as they arise and so saves oodles of wasted time. Autoguiding, of course, as well as automated dithering as you point out.

All these things can be done without a computer driving the scope and camera, of course, but it's just that much more effort  and fiddle-faddle.

Not gonna argue with the choice of Pi and Astroberry, since I chose essentially the same system! (I bought StellarMate OS because it was simpler than AB back then, but same same.) I should note that an update to KStars sometime in the past year or two includes a Bahtinov focusing metric, so you can slap on the mask and look at numbers instead of squinting at spikes and trying to decide if it's really centered.)

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