rickwayne

I feel you, man. I resorted to narrowband imaging because of the light pollution in my neighborhood.

Yeah, it admits that it's got a pink problem!

I seem to recall seeing someone post that they were waiting for those to become available. No idea when it would actually show up, but now you can order one.

I honestly lost track of how many LRGB subs went into this. I'm thinking something between 6 and 10 hours of total integration time, done as a mosaic because I wanted a little bit more room around the galaxy. That added a TON of problems because of course most of the imaging sessions did not go as planned so I had wildly different numbers of subs in various colors in various places. Also, some serious variation in the Moon's illumination over the six nights of imaging between the end of August and mid-November. Primarily Astro Pixel Processor -- thank Bog for the gradient elimination tool -- plus a lot of work in Photoshop.

I feel as if I'm getting some really decent performance out of my CEM-25P, even with 17 pounds hung on it I can sometimes wring 0.6-0.8" total RMS out of it guiding. But the amount of tweaking and obsessive care that requires is rather fatiguing, and I'm thinking that I'm ready to liquidate my tax refund, Christmas money, and the CEM-25P in favor of a center-balanced equatorial of higher capacity and finer tracking performance. Too, someday I'd like to go longer than 362mm, so I don't have to sit out Galaxy Season every year. So I was going back and forth between the CEM-40, which would be reasonable, and the CEM-70, which would be twice the weight -- I normally set up and tear down every time -- and 30% more money. But...but...shiny object! Last night I had a revelation. I have a wonderful 11" Dob in a beautiful wooden cabinet. I never figured I'd ever image with it other than maybe the Moon or planets, but it occurs to me that with a CEM-70, I could literally bolt a nice big Losmandy rail on the cabinet and mount the sucker. Voila, instant 11" f/5 imaging Newt! It never occurred to me because it seemed absurd, but it's still got to be under 50 pounds, which the CEM-70 could actually carry. So now I just have to break it to my children that it's mac and cheese for four months, and I'm golden.

Gently, gently. Don't spook him. We'll have him over to the Imaging Dark Side before he knows what hit him :-).

Oooh oooh oooh I know this one! One way is to close Ekos and find your object in KStars, then right-click on it, select your mount from the context menu, and choose "Goto". You can click the magnifying-glass button in the KStars toolbar first if you want to search by name or catalog designation rather than hunting in the planetarium. Even easier, if you're already in Ekos, is to click the "Mount" tab, click the "Mount Control" button at upper right, and notice that that dialog also has a magnifying-glass button. Brings up the exact same search dialog, when you find the thing you want with that and close it the object will now be listed in the Mount Control dialog. Click "UNPARK" (if necessary) and "GOTO". Bingo! It took me a LONG time to notice the second method. Don't feel like the Lone Ranger, Ekos scatters things about its user interface as if it were the cockpit of a 1960s Russian fighter plane. Setting the target in this way is also useful when/if you set up plate solving, which is the golden road to ease and riches. I never bother to star-align my mount, ever. I just do the Mount Control thing to get it in the general neighborhood so the plate solving will be quicker, click "Capture and Solve" on the Alignment tab with "Slew to target" checked, and enjoy the little robot's work. Even cooler is that you can come back to a target later by keeping one of the FITS images from a previous session around so you can click the "Load and Solve" button. I just do that with the mount at zero position and it nails it perfectly.

Not nearly as sexy as the Horsehead though >;-}

Note: In Step 2, do not bash your mirror or sensor against the end of the eyepiece tube. Ask me how I know. Also, be sure you're pointed at a really distant object.

Respectfully disagree. Plate solving can work with a small number of stars, and the image can be of pretty terrible quality. (I am a world-class expert on astro images of terrible quality.) So my advice to Capt. Slog: Go ahead and get the T-adaptor. Don't mess with eyepiece projection. In daylight, hold your lensless and adaptor-less bare DSLR up to the empty eyepiece holder of your scope, running live view. Wave it back and forth until you have a rough idea of how far out it has to be to achieve focus. At night, center a bright star or planet in the eyepiece. Replace the eyepiece with the T-adapter and camera. Run the camera at the highest ISO setting that will work, live view again. Rack the focuser until you reach the approximate distance from Step 2, then focus manually. Don't worry about perfect focus. Mark that spot on the focusing tube with tape (if it's further in than the eyepiece focus position), or some other reasonably reproducible method. Shoot various exposure lengths until you find one that gives you at least a handful of visible stars. Put the eyepiece back in, get pointed at your target. Replace with the camera again. Rack to the tape or mark. Shoot the exposure found in Step 7. Profit! (I.e., upload a JPEG to nova.astrometry.net and see exactly where you were pointed.)

Adrian gives good advice, but I would modify it slightly since you're looking at narrowband. ZWO actually did some experimenting and their results indicated that if you want to maximize dynamic range (i.e. get dim stuff but not blow out stars), use the lowest gain. If you want to minimize read noise and shorten exposure times, use the gain where read noise is low but you still have some kind of dynamic range left. For me, that means 65 on my ASI183MM for LRGB, because star color is a thing. For narrowband, 178, which is the max practical gain on that camera (or so I read from the greybeards) and I'm not getting real star colors in the first place. Likewise for temperature, there is no significant improvement by cooling past the knee of the curve and so it's best to pick one reasonable temperature and always use that unless environmental conditions absolutely prevent it. For the weather in Wisconsin that's -10C. Likewise exposure, you can drive yourself nuts looking for the perfect exposure but again the gains are really marginal once you've got the peak of the histogram clear of the left edge and aren't blowing out stars. Piling on the sub-exposures for more integration time is a much more flexible and sustainable strategy. You can always go out and shoot more! Since narrowband filters aren't passing nearly as much light, you'll likely wind up with better results if your standard narrowband exposure time is as long as you can get without mount problems. I'm using ten minutes now, but have gone as short as 30 seconds (!!) when my autoguiding was cranky. Finally, for a first outing, consider simplifying your life and just capturing and processing Ha. It's by far the dominant signal in that target, and IMO a monochrome image of the Heart is not bad at all. The Soul is less interesting graphically and perhaps cries a little more for color.

I know that "just use the tools that I favor" is not the help you asked for! But really, you should know that Astro Pixel Processor really shines at integrating data from multiple sessions/multiple filters, and at composing rotated, offset, and mosaic images. There's a 30-day free trial, and it works on Windows. Its limit ease-of-use case is "load up all your lights and calibration frames, then click one button". Usually the multiple-filter thing is used to produce separate integrations for each channel which you combine later, but you could lump 'em all in too.

You can easily do that yourself, by the way -- just go to nova.astrometry.net and upload your image (they list supported formats). You will get back exceedingly precise information on exactly where you were pointed, how much the camera was rotated WRT the standard coordinate system, objects in the field of view, etc. Shockingly (to me, at least) that plate-solving software can also be run on your own computer. In fact it runs on a Raspberry Pi! Most folks using computers to drive their telescopes depend heavily on it. Sky ignoramus that I am, if plate solving tanks for some reason, I'm left literally stumbling around in the dark.

I'll reiterate the classic beginner advice for deep sky, so long as you understand that plenty of people violate it and do well. As Somerled7 notes, planetary is an entirely different world, so much so that getting satisfactory pictures of both from the same equipment is a major challenge for a beginner. (And of which I am stunningly ignorant.) Nebulae come in all sizes, but there are plenty of ones big enough that you don't need a lot of magnification. I use a 362mm scope and have yet to run out of targets. You can look at my image catalog and decide for yourself if I'm worth listening to. Deep sky photography is counter-intuitive in many ways. Most folks think first about their optics, and that aperture and focal length are key. For deep sky, the mount is ever so much more important than the optical tube assembly (you'll see "OTA" a lot), simply because you have to do time exposures to get anything at all. 30 seconds is probably the practical minimum, and you have to have something that tracks to within a couple seconds of arc over that time or you'll see (at best) degraded detail and at worst big streaks instead of stars. A second of arc, as you probably know, is 1/3600 of a degree. If your mount ain't up to the task, ain't nothin' you can do to ease the frustration. The quality of the optics does matter, but the size, oddly, much less so. Visual astronomers are all infected, to a greater or lesser degree, with "aperture fever", since a big objective gathers more light and can theoretically resolve more detail. For deep sky, the answer to "more light" is to merely increase the number of frames taken for stacking, and given the atmosphere's turbulence ("seeing" effects), we rarely get anywhere near to the theoretical limits of our optics. Again, my images are done with a 70mm scope. There are certainly dozens of great targets that my scope can magnify enough to get a good picture out of, and some huge ones (Andromeda, North America Nebula) wouldn't even fit in anything much longer! Procedure and processing is an enormously important part of your game, independently of what you use to take pictures (or "acquire data", as astrophotographers frequently say). And the whole process, from equipment setup to processing, is a chain with lots of places to go wrong. Keeping it as simple as possible is a great strategy for ensuring that you actually enjoy this. So, the advice is basically this: If you already have a decently capable camera and some telephoto lenses (especially primes, better suited to astro), use gear with which you're already familiar. Figure out how much you can stand to spend on a mount. It will be a precision piece of equipment built for a pretty small market (code for "oh my Bog, the PRICES!"), but you really do get what you pay for. A good mount with "goto" capability, enough capacity for starting out, and sufficient precision to do the job will probably cost upwards of US$800 and a thousand is a safer bet. You can put a camera on that and start learning the game immediately. (Note that older telephotos from the pre-auto-everything days can often be picked up quite cheaply, and some have terrific glass.) Alternatively, camera tracker platforms (e.g. iOptron SkyTracker or SkyGuider) are much less expensive. Less capable, but used within their limits they can do some wonderful deep-sky stuff. If you really want a scope (perhaps you want to look through it too!) straight off, the "classic" advice is to go with a short, small-aperture refractor, preferably an apochromatic one. The shorter and lighter the scope, the cheaper the mount that can adequately run it; remember, you're all about not buying trouble for yourself at this stage! Refractors are pretty much maintenance-free, too. Most photographers use a field flattener so that the image is edge-to-edge in focus, but that's optional for starting out IMO. Finally, if you ignore all the advice above -- feel free to! -- I strongly urge you to get one of the books on the subject and have a look. A grounding in the principles is priceless when you're making these decisions and when you're sitting there in the dark trying to troubleshoot something. I'm a big fan of Charles Bracken's The Deep-Sky Imaging Primer; you will often see Steve Richards's excellent Making Every Photon Count recommended here; and Jerry Lodriguss has several great books, and also hangs out at the Cloudy Nights online forum so you can pick his brain directly. And welcome! Be warned that this stuff can be quite addictive. Space is pretty, even at a quick glance, but it's deeper than it looks. 🙂

Cosmic ray? (Seriously.)

I am pretty excited about it too. Really does look like a big leap. The jury is still out on actual quantitative results for this particular detail, but: One of the possible advantages is that seeing effects average out over the stars -- in any reasonable guiding FOV, the stars are moving independently. (Better astronomers than I did the math, using the experimental results of how the atmosphere actually behaves at various scales.) This means that "chasing the seeing" is a lot less of an issue than it used to be and so if you have a squirrelly mount like mine that needs lots of little corrections, a short guide exposure makes it possible to address them before they get big enough to affect the image. I'm mostly using 1 second these days, which is a big help for my overloaded CEM-25P.

10 hours of integration time in this over two nights. When I saw I was getting 0.67" total RMS with my newly-compiled PHD2, even though my target was still mired in tree branches, I tried a twenty-minute exposure and just boggled at the results -- 1.3 HFR, which is better than I usually get with five minutes! 20 minutes just seemed too risky, though, so I went with 10. After the meridian flip an hour in, the numbers got worse, but still much better than I usually see. This is reprocessed from before, using much lighter stretch on the OIII data -- the blues accurately represent where the oxygen glowed in the data, but are hand-masked in. I also used SiriL's green noise removal tool, hit a bit more stretch with SiriL too, and didn't lean so hard on the data in Photoshop. Spent quite a bit of time on the starless layer hand-retouching star halos in the starless layer with the Healing Brush tool. Tech deets, as always, on Astrobin.

Plenty of commenters over at Cloudy Nights report a noticeable improvement. I certainly did too, although I'm always trying to tweak the rig and the params for better guiding so it's hard to say PHD multistar was the cause. Still, when you go from around 1.2" total RMS to 0.67"...that ain't bad news. For Linux users, AFAIK you still have to compile PHD from source to get the new shiny. Fortunately that's easy and straightforward, takes less than half an hour on a Pi 4.

For emission nebulae, an unmodded DSLR's IR cutout filter will remove much of the predominant deep-red hydrogen-alpha signal. Still can be done, but you're starting at a disadvantage. See astronomy.tools for matching scope to camera sensor. I have a 183 for my 362mm F/L rig and love it.

That's what I usually resorted to. You can also use timed exposures rather than live view, it's a pain but if you're patient it can work. The spikes get fat and insensitive if you get too bright a star, but that sounds like a problem you wish you had at this point! For timed exposures, bump the ISO up to something ridiculous (you can do this with LV too if you haven't already tried it. Don't worry, no one EVER forgets to dial the ISO back down. Or to remove the Bahtinov mask...

That has been my experience exactly. Well, something was making KStars crash, certainly might have been multistar guiding. Hadn't had issues before StellarMate OS 1.5.5 came out.

<slaps forehead> Well of COURSE! I would imagine that for guiding, the finder shoe is still less rigid than rings mounted along the scope, but I bet that nails the biggest source of flexure right there. Good one!

In my experience the biggest problem with finderscope holders is that they privilege adjustability over rigidity, so they frequently have something like an O-ring as one point of contact, with 3 screws as the other. So the whole shebang only as rigid as the rubber. Heck, since a guidescope needn't be perfectly aligned with the imaging scope anyway, you could try sticking in some rigid shims as a first fix if you do find flexure.

Nice one. You are to be commended for NOT leaning on the "sharpen" slider until all your nice tonality boiled away! I'm always torn between full-Moon images like this, and ones that display all that tasty topography and highlights-in-shadow detail by the terminator.

For what it's worth, I did this image of the West Veil with an f/4.5 scope one night when guiding failed and I was limited to 60 seconds. Dunno if it's "meaningful" but there's certainly a signal, even in O-III which as you know is always much weaker than Ha. Likewise this Elephant's Trunk is also composed of 60" exposures.