Wonderful presentation. However, the spectroscopy introduction using the flame example is not quite correct. The blue flame color generally doesn't correspond to that in blackbody emission. Rather, the blue is usually from chemiluminescence of CH*, and thus may not have temperature correlation. The yellow is generally from soot incandescence, and thus would have better blackbody emission correlation.

Ty for this

Great presentation, with some very useful tips both for imaging and processing. I've been doing AP for years, but I've not had the greatest luck with Milkyway photography with an SLR. I use Canon cameras because I've used them for decades, and notice that most notable Milkyway photographers use Nikon, but suspect it's more my technique than my equipment.

suddenly back focus is 55mm. last summer it was 105mm. I wonder if there is a day out there somewhere when I understand what hack focus is.

Is this Molly? The Astronomy columnist? I camped next to you at Cherry Springs a few years ago. Nice to see you.

Excellent, excellent presentation! I cannot possibly argue with the math or the logic. But there's at least one aspect of this Tim really didn't get into--practicality. This is a very difficult avocation. And one of the most difficult parts of it is data management. I've set three different exposure times and one gain (unity) that I use 99% of the time. 60s for RGB stars for narrowband images, 180s for LRGB for broadband, and 300s for narrowband. I do this across five rigs at five radically different focal lengths and five very different F ratios at two locations--one remote and one here at home. The main reason is a simple one: I'm simply not going to manage six or seven different exposure times combined with multiple gains and all that implies--flats, darks, flat darks, biases, and lights. At that point, this activity becomes an unmanageable nightmare and is just no longer worth doing. I do want my images to be the best that I can make them--but there's the rub. The best I *can* make them--that is, in the real world. I have a life outside all this, too. While, like I said, I cannot disagree with the math or the logic of Tim's arguments, I simply will not change what I'm doing. Tim even undercuts himself and--tacitly and unknowingly--agrees with me at the end when he says he has a project where he's going to up the gain to reduce the necessary exposure time. The example he showed of single subs shot at increasing exposure times I find uncompelling. It's one thing to compare a 3 minute sub to an 18-minute sub--one thing that's not at all informative. Compare 6 three-minute subs stacked to a single 18-minute sub. Hard to do since you can't really stack one sub. But consider this: Compare a stack of 6 three-minute subs where one sub has a big, bad airplane streak through it to an 18-minute sub that has a big, bad airplane streak through it. Nor did Tim really dive into why a stack of 6 wouldn't reduce shot noise to a similar level as one 18-minute sub. That may be buried in the math and support his argument, but it's a point he really didn't cover. He seems to contradict it by asserting that one reason we stack to reduce shot noise. This highlights one of the technical aspects Tim failed to cover, although he did briefly mention some of the drawbacks of his proposed approach. But the drawbacks are significant. If I have 7 hours to capture Ha for an object and I take 30-minute subs (14 subs), how well is the rejection algorithm going to handle the aforementioned big, bad airplane streak? And how well will that algorithm handle the same streak in a stack of 140 three-minute subs? I don't know for sure and Tim didn't say, but my money would be on the 140. And when the wind kicks up hard, like it often does at my observatory, and toasts a sub, do I want to toss 3 minutes of data, or do I want to get rid of 30 minutes of data? What if seeing changes significantly over a short period? What's my FWHM going to be on the best 3-minute subs versus the 30-minute sub? These are questions largely unaddressed by this talk. Finally, Tim did not present a single concreate side-by-side example of the same object shot with shorter subs versus longer subs with the same gear under similar conditions. If you really want to convince me, you'll have to produce at least one example of that--and optimally several examples. Now that I've crapped all over this talk, I want to point out that that is not my intent. I found it to be an excellent talk with all kinds of valuable information and strong arguments for most of the assertions Tim makes. One concession I might be willing to make in the future because of this talk is to start shooting LRGB at 0 gain, but I'll have to think about that, and I'm not there yet. But the main value of this presentation: to me is that Tim provided a boatload of facts and all kinds of useful information. And no one can argue with the results Tim gets. They are simply top shelf. Thank you, Maestro!

Great presentation. Lots of good points well made. However, at about (1:22:00) you encourage longer exposures due to retaining more levels, but this ignores the stacking factor that creates intermediate levels at the rate of Log Base2(N) where N is the number of subs. So I think your statement is incorrect in this case as it only applies if are talking about one single exposure, but you need to be talking about the same total integration time. When you do that, what you lose in a single short exposure, you regain in the stack because with the shorter exposures you are stacking more of them and so your log base2(N) is a larger number and that’s where you reclaim those digital levels that you think you had lost. And this is where you do not lose levels, taking shorter exposure as relative to longer exposure because you do more of them and you reclaim them in the stacking. Each individual exposure may have fewer level levels, but the stack will have all of the levels and you will not get blotchiness from that. I encourage you to do the math on this and you’ll see that it’s true and so you do not increase your single expose your time to increase the number of levels in your final image. Your later example (1:24:00) is with showing only single different length exposures… I think it’s well understood that when looking at one exposures, a longer one is going be better because that also represents a longer integration time so you’re comparing different integration times (10x longer!)… that’s the important factor in that case. What you need to do is stack 10 of the 120 second exposures, and then you’ll be back down to only the read noise difference. Without making the total integration time equal, it’s not a proper comparison. To compare 120 total seconds of integration time to 1,200 seconds of integration time is going look better as you captured 10x the amount of data. Again, a great presentation representing a lot of hard work. I think these are is just two corrections needed in an otherwise great presentation.

Why dont you use a wifi extender close to the seastar to improve the range.

By chance have you tried a field rotator? I wonder if NINA can figure out the amount of rotation needed every couple of minutes to keep the object fairly well oriented each time it does a center operation. Thanks for the presentation!

EXCELLENT VIDEO MOLLY! This may seem a bit overwhelming at first but break into parks (short goals leading to the long term goal) and you will benefit at each step along the way. I have been into this hobby for ten years now and two things that has made it so much more enjoyable is setting up remote access and switching to NINA. NINA is amazing (and free) . . . a true game changer. But like everything else in this hobby there is a learning curve. But worth the time and effort. And plenty of wonderful people, like Molly, to help along the way.

I have been using N.I.N.A. for some time now and I am a dithering kind of guy. NINIA has all the options and controls you are describing including 'settle time' to allow guiding to stabilize before continuing. Also, I made a spreadsheet for dithering and just plugin the camera/scope specs and bingo. Of course in NINA it becomes part of the setup profile I choose for the night. So once figured I'm good until I change something in the setup. Or something just like that only different.

Hey! Some of my best friends are weirdos. So I resemble that remark.

Any way to contact Mr. Bracken...........I just purchased his book The Astrophotography Sky Atlas and want to inquire about getting a spreadsheet version of the Object Index tables so I can sort them in different arrangements to use with my Seestar S50.............purely amateur and no intent to share the tables. Thanks!

Spectacular

Simply inspiring. Alistair has a wonderful approach to such a challenging project. Simple tools, massive perserverance and persperation and an astonishing image.

That clear pixel sparse color sensor is a game changer. You can select the filtering per project and get all of the photons you want on them.

Great discussion. The only right answer is that there's not one answer. TBTG... !

Great video. I'm wondering if I could access my Seestar as you do with the ASIAIR. Looks like a similar interface.

Great process example, thanks. If you don’t have topaz studio, the high pass filter will do much of the same using a variety of different scales and applying them with masks or painting them in if you mask the entire adjustment layer.

Thanks for sharing

Great catalog! Thanks

Brilliant video discussion. Such an impressive piece of work!

Just discovered this video-i have encountered Gary’s astrobin images but never realised this spreadsheet and pdf existed. Just blown away by the effort involved here. ❤ Personally i limit my own imaging to 30-60 mins total using OSC and filters with my 8”SCT and FR0.7 because there are just so many targets! Now i have even more to find 😂 I would however recommend imaging “APM 08279+5255” - a 15th mag target but a lensed quasar at 12billion LY away. I believe it is the furtherest object you can see in an amateur scope and so imho a great extra for the catalogue…

Very nice Presentation. I have worked with SharpCap for a couple of years now and I have found it to be an awesome program. I have yet to try the Planetary Live Stacking feature but now that I have seen Michael Owen's presentation twice, I'm anxious for my next viewing session. I'm not a fan of post processing so this feature in SharpCap is a welcome site. Thank You Michael for a job well done. I'll let you know how my session went. Ernest

Maybe I missed something, but wouldn't a process like this (adding a starless comet, which is fine, to a star only image) completely kill any nebulosity or galaxy present in the image since all the background features are lost stacking onto a moving comet?

Hi guys thank you for the information, very helpful, I’m setting up a new focuser, specifically the PrimaLuceLab 3” esatto with 0.04 micron per step, what will be the easiest way to determine my step size? thank you.

What are there star diffraction spikes if you shot this with an FSQ106 refractor?

Very helpful! Thx

Why haven't the camera mfr's offered a larger pixel CMOS for longer focal lengths? At 3.76um you need Chile grade seeing for anything over 1500mm.

While it does create a sort of pre-covid charm, if you can understand pixel scale, guiding, the Dawes Limit, etc, you can understand muting the phones and apps during a recording. 😜

umm i use an external guide scope all the time with my C14 edge. You have to when you are using Hyperstar. Off axis guiding at this focal length is worthless, especially when you are going after deep objects like the galaxy clusters in the Abell catalog.

that Skype call really freaked me out :D

Good presentation and discussions. Thanks Ron.

Great video! Does anyone know why the sequence titled 'vdB 9 - Helping Hand - Target Loop' appears different from the first target loop? There seem to be two imaging loops: one for broadband and one for narrowband. I understand this might be related to the moon's position, but it's hard to follow exactly when this will occur-perhaps during a new or full moon?

Very informative presentation. We need more of these, they’re very helpful.

My seeing is generally poor (northern New England), but I've had about as good as it gets in ground winds gusting over 25mph, and 5", or worse, in dead calm..... Maybe it's different in more arid climates and/or at higher altitudes, where professional telescopes tend to be, but for most of us, I think thermal convection and turbulence is much more of an issue than air movement alone, though air movement can exacerbate thermal turbulence.

A nice presentation and a powerful tool to help us tune our systems. I'm a user of hocus focus as well as a tilt device. The process is tedious to say the least.

Too bad you didn't mention the different fitting options ( Hyperbolic, Trends, Parabolic, etc ...) and explain how to choose the best one

RE: the use of offsets vs. not. It is not all about speed. The variability of results when initially obtaining the offset number is indeed often large - do not accept a single run as being accurate! This can be dealt with by using multiple runs of the offset plugin until you statistically converge on a reliable and accurate number. It can take many runs and several nights but only needs to be done once per setup. Additionally, variability still exists if you do not use offsets and is often larger with narrowband filters due to fewer and poorer stars which can decrease the accuracy of narrowband focus. Further, the typical procedure to use Luminance to focus when using offsets is, in my testing, misguided. Better results are often obtained by using a wideband filter centered on the visible (aka green). Finally, using offsets allows one to take more than one sample per focus point which further improves reliability with minimal time impact. www.astrobin.com/users/CCDnOES/

Wish I had been available to join the stream last night because my question would have been around why aberration inspector fails, even though running hocus focus results in a very good fitting model. This is a constant thing, too. I'll run hocus focus and get back a curve with a model fit of 0.99. I run aberration inspector on exactly the same star field and even though the curve looks the same, aberration inspector throws up an error saying the model doesn't meet requirements. Why?

Why are there more ads during your videos than anywhere else on youtube? I stopped listening after the 6th doubled-ad only 30 minutes in.

Excellent episode.

Adam, super helpful as usual. Thanks! Mark

Gary's compendium is a great reference and tool for planning your imaging.

Planning of targets to photograph is one of exciting and enjoyable processes in astrophotography. I just wonder who uses a table of targets planned by someone else.

I almost didn't watch this. I'm doing visual astronomy now, and globulars look interesting. Thanks for giving me a bunch of ideas 😊

That was a grrat presentation. I'd say it is a bit frustrating to not have any more details on the Photoshop actions, they looks really great.

Thank you very much, Craig !(Stephane from Belgium)

Great " SMART" presentation Thx Craig

How about the distance from a coma corrector and a Focal extender like a Tele Vue Powermate?