raadoo

Uploading the unprocessed, unstretched, stack would make it easier (for me, at least) to work out a battle plan. As much as there are general directions for galaxies and nebulae and planets, I find that the acquisition setup and its result often influence processing strategy more than going through a formula. Looking at your process above, I can see some star bloat (overstretched, maybe?), overly noisy output in faint areas, crushed shadows and some unnatural colour cast in Andromeda itself.

That's the spirit!

Wait a sec... didn't you say you were one of us in the faff-free club? Odd that you went with what is probably the most faffy kind of scope type 😂 That being said, I'm glad you did go for the RC. If you can live with it, coming from the FRA400 and its lack of maintenance and collimation, I'll think twice about RC's in general (though unlikely that I'll follow in your footsteps and get rid of my FRA400). So, looking forward to your reports, Lee!

@Lee_P That's bananas. Such a good result! Seeing you put in 28h into a target and get such a fine result just fuels my desire for moar inturgrrtion!!! 😂

Don't forget about using a tiny 1" OSC sensor, on top of all that 😂 Subs were all 300s.

Pairing an ASI183MC Pro (2.4μm) with a Skymax 127 at 1500mm native is not generally a recommended setup, especially not from a Bortle 6 inner city location. The pixel scale alone, at 0.33 arcsec/px, is so oversampled that you're essentially just getting a lot of blurry pixels. And I'm not arguing against it; that's absolutely the case here. Binning x3 will get the same level of detail without the hassle of dealing with 20MP subs. But hear me out. I really wanted to get the Bubble Nebula. It was on my to-do list. And I'm in a situation right now where my next best scope is not in the cards in the foreseeable future. So I could either go for another wide field target or frankenstein some sort of setup with my only other scope: my Mak. So I lifted the ASI183MC Pro + Altair Filter Holder w/ Antlia ALT-T + ZWO OAG off my wide field setup and through a lucky combination of adapters managed to stick it to the back of the Mak 127. For focusing I had to rely on the stock focuser without so much as a Bahtinov mask (that was ... uhm ... "fun"). Speaking of focusing, I soon realised that the Antlia filter, nice as it is, blocks so much light that I was unable to focus or polar align without going to 10s exposures, which wouldn't work because of drift. So the whole process was to do a first focus with no filter in the slot, polar align, enable tracking, then slot in the filter and refocus. Then refocus every ~30min because temp deltas at night are horrible right now in my location. This whole song and dance went on for four nights these past two weeks or so and while I can take some credit for careful planning and choosing the best equipment I have for the job, credit where it's due: my beautiful red RST-135 tracked and guided like a champ. I was consistently getting ~0.3" RMS, sometimes going down as far as 0.2". It wasn't all perfect and I did throw away about 40 subs but what I ended up with were 133 decent subs that yielded the final result. So here I go piling on to the same age old advice: get a good mount. If you want to throw a like or just a look, the image is also on Astrobin. So, despite the math saying it's not the best setup to throw at a Mag 10 emission nebula and it certainly doesn't compare to what some of you have done with this target, I'm really proud of the result and I see it as a landmark in my own journey into astrophotography. Thanks for reading!

You got it, with the one caveat that if you want to take advantage of the computational speed increase when dealing with the smaller files, you'd have to bin in camera, so the actual .fits output are images of 2082x1392. That being said, one interesting application of binning an OSC, like your 2600MC, not in camera, but in post, is that you can essentially use the binned data as a Luminance layer, while the unbinned data, undersampled as it may be, would be user for RGB (PI's LRGB Combination to the rescue!). I haven't had a chance to try this myself, but it does sound like it's worth a shot (pun intended).

It's probably hard to get your head around it because it doesn't seem like focal length comes into play at all. When in fact, image scale is quite affected by focal length, as the formula for image scale is PixelSize* 206 / FocalLength. So the expanded formula for overall system speed becomes: A²*(μ*206/F)² A = aperture, μ = pixel size and F = focal length. This helps to draw the, now obvious, conclusion: a system gets faster as aperture and pixel size increase, while focal length decreases. To add to @vlaiv's (a zillionth) comment about binning, if you bin, you essentially *2 the above formula. So if we take the scopes that we've been discussing in this thread and apply the formula using your 2600MC, we can see how the ones with the larger aperture and lowest f/ratio (affected by focal length) result in the faster systems: Vixen AX103/825: 9374 APM LZOS 100/800: 9409 Askar 130PHQ: 10281.96 ES FCD-100 127/952: 10582 Skywatcher 150PDS: 10609 TS 115/800: 12188 ES FCD-100 CF 102/714: 12361 TS CF 102/714: 12361 Askar 107PHQ: 12622 TS 106/700: 13843 FRA400: 19510 👈 you are here Vixen R200SS: 24087 Boren Simon 8" (at f/4): 24087 For the three newtonians I factored in their central obstruction before going through the formula. If getting something speedier than the FRA400 is top of your list, there are options if you must stick with refractors, though you may not like them: Televue NP101is: scores 21153 but costs €6000 and has a focal length of 540mm, so not that far off from your Askar. And then there's its bigger brother the NP127is which scores 22458 and costs €11000 🤯 ES FCD-100 127/952 with the 0.7 reducer: scores 21703 but is large and long. But it's within budget, the CF version is light enough and even with the reducer it comes to 666mm. This speed increase applies to all the refractors above if you stick a reducer in their tail end. I specifically chose this one because even reduced it still falls within that ~700mm focal length range you're after. Sharpstar 121SDQ: scores 19027 but costs €4500 and weighs 9kg and is discontinued (but maybe you can find some new old stock?) Askar FRA600: scores 19410 is within budget but only slightly more focal length than the smaller FRA400. All this to say I wouldn't worry as much about overall system speed. A quick run of my own setup through the formula and mine get a measly score of 7970. I'm content with just factoring in more integration time.

I reached out to TS to ask about the ES 152 MN. Copied and pasted below: I see that we have ordered them, but honestly don't know if we can get them delivered.I find only discordant informations. in any case I asked to check this fact to our purchase office, in cae the webshop will be corrected

In my case (FRA400 + 183 sensor), sampling should already be realistic in terms of my local seeing (~3"). Pairing a larger scope (4" - 5") with a 571 sensor like yours means I would end up with similar sampling rates (but significantly better S/N). The 571 sensor I'm eyeing is a mono one, to pair up with my current colour camera. So it's more about doubling up and giving myself more imaging flexibility while reducing time spent on a single target, but - and this is coming back to sampling and bad skies of course - for those occasions when I go to a dark site (B2), I should, theoretically, be able to stick the 183 sensor on the big scope and get decently sampled results. Apologies for a bit of introspection: At the end of the day, though, we're not professional astronomers, we're just passionate about the crazy stuff that's up there in the sky. So, if you under or oversample your images, is that the end of the world? Did any of us that started out by pointing a DSLR attached to a modest camera lens up at the sky - with or without a tracker - even know what sampling was? Did that lessen the fun or awe or just child-like giddiness when you see that first image of Orion or Andromeda or the Moon and you feel like you trapped lightning in a bottle? And sure, we into imaging are often gear-heads of the highest caliber and can't help but dive deep into all the fun technical details of this hobby, but I for one won't let technical limitations, theoretical or practical, get in the way of having plain old fun. And if I'm lucky, I might also learn a few things along the way.

Intentionally didn’t include those as: The ES 152 was discontinued last year The SW is 12kg, so too much for Lee’s mount But, for sure, if one can find an ES or Intes on the used market, they’re worth considering.

@Lee_P I’m in the same boat as you - got an FRA400 paired with a 183 and am looking for an apo in the 700 - 900 focal length range to pair with a 2600. I’ve not yet reached a decision on what I’ll move to next but maybe my shortlist will help you narrow your search down or even prompt others to share their thoughts: Refractors TS 115/800 - €1500 - affordable and gets a lot of praise from knowledgeable folk (e.g. @vlaiv). ES FCD-100 CF 102/714 - €2000 - Optics should be good and that carbon fiber means your mount has an easier time swinging the rig around. TS CF 102/714 - €2000 - Looks solid from a mechanical point of view, with all the right imaging accoutrements and each one gets tested before shipping. TS 106/700 - €2200 - FCD-100 should perform really well but it’s pretty new and untested. ES FCD-100 127/952 - €2700 - Bigger brother to the 102 is as light as a 4” aluminium scope but hey, bigger aperture. Do keep in mind that it’s pushing close to a meter in length for the scope alone (oversized dew shield extended). Vixen AX103/825 - €2900 - Vixen often get overlooked and no one knows what glass they are using but its pseudo-petzval design is quite appealing. Askar 107PHQ - €2900 - A thing to note about Askar’s Petzval scopes is that there will be some variability in quality. My FRA400 is no lemon but it does show chromatic aberrations across the field, whereas yours is a better corrected unit, from what I’ve seen in your images. APM LZOS 100/800 - €3900 - A lot of dosh but by all accounts should be an amazing optic even though it’s quite slow at f/8. Reflectors Skywatcher 150PDS/750 - €410 - Cheap as chips and a large community of modders means you should find help for any issue. And f/5 is going to be more forgiving of collimation errors. Vixen R200SS/760 - €1400 - Despite the thick vanes and mediocre focuser, this one has a neat party trick in that it can become an 1120mm f/5.6 scope with the use of the Extender PH. And you can switch out the tube for a carbon one later down the line. Boren Simon 8”/568-800 - €2200 - This one’s interesting because it’s a carbon tube and can play double duty as an f/2.8 or f/4 scope with the use of a TSGPU Coma Corrector. TS 8” ONTC w/ FeatherTouch ~ €2900 - You do get a fine scope for the money, but be prepared to wait a while to get it and at this price you better love newts. I’m intentionally leaving out RC’s from this list as you mentioned wanting to faff about as little as possible (a sentiment I echo), which kind of only leaves newtonians on the table for the focal lengths you’re after. For what it’s worth, I’m personally leaning towards the ES102CF, as it seems to offer the most for one’s buck. I’d spring for the 127 even, but on my narrow balcony I’d probably end up crashing the scope against a wall. Alternatively, the R200SS and it’s party trick makes it appealing for next year’s galaxy season without moving to an SCT. Did I miss any other potential candidates? Slightly off-topic: Sharpstar just dropped news about their upcoming Z4, which is a 100mm f/5.5 refractor. Maybe they’ll follow up with a 120mm f/6? Strange naming though; not sure what the 4 means. Or why they needed another refractor in this focal length / f ratio to compete with their own 94EDPH, 100QII or FRA600?

No surprises, then, in which scope bests which other scope. Interestingly, I've been eyeing the DZ myself, but as I'm primarily an imager, I'm attracted to by its flourite magic, lightweight build and impressive spot diagrams in a mono imaging setup (which would bypass the issue of it being a doublet). I'm sure, just like its DC and DF brethren, it does a wonderful job in a visual lunar context and therefore is no surprise to me to see you compare it with the µ180. I actually have a Mak127 and while the general consensus is that it's a fine scope, my experience with it has been less than positive; for visual (planetary and lunar) it does a good job, I'll give it that, but imaging with it has left me unimpressed. It's got contrast, sure, but even when you're in focus (using the old last turn counterclockwise trick to mitigate mirror flop) the image is a right soup. Before you all jump on me about seeing conditions, I've had it out at least 40 times in the past year and half, on nights of good and bad seeing and it's always been soup-ville. Usual cooldown is about 2h and I always use my Astrozap heated dew shield to keep the meniscus from dewing up. I even retrofitted a crayford focused alongside the primary focuser to try and really nail down the focus. Still unimpressed. It does do the mak thing of holding collimation like nobody's businesss, however. The CC6 is definitely best bang for the buck - right up there with the SW 130PDS and the Sharpstar76 - and if it were around when I got my Mak127 (or had I known what i know now), I'd have gone for it as my first lunar/planetary scope in a heartbeat. Well, I guess here comes the long wait of saving up for a Mewlon. First world problems, eh! Thanks @HollyHound & @dweller25 for your input!

As one of the lucky few to have such a wide range of small cats, and me someone looking to up my lunar game … which would you choose as your only lunar scope? The Mak127, C5, CC6 or Mewlon 180?

I know what you mean, and you're right, it's generally a bad idea. To me, though, it's a bad thing turned good as it sort of forces me to go for longer integrations to achieve a decent SNR, the consequence of this being I also end up racking enough integration time to get some pretty decent OIII signal as well.

I got mine from Teleskop Express in Germany as I'm based in the EU. In the UK, it seems auntie FLO doesn't stock it, but 365astronomy does.

I’m in a B6 zone myself. Started with the L-Pro, moved to L-Enhance, now using the Antlia ALP-T. Hands down, the Antlia wins. It transmits sligtly better in OXygen than Hydrogen, but to me that’s a good thing because it means I get a bit more than just pure red out of emission nebulas.

@johnfosteruk Really good shout, there. Getting detailed spectra on exoplanets means we're far more likely to find Earth-like planets. Though, personally, I'm more interested in the weirdos; you know, the ones where it rains diamonds or there's never ending storms, the kind that make sci-fi seem tame by comparison.

Thanks to all of you who contributed to this thread, my heart's pretty set on an LS50THa. Speaking of the Lunt, does anyone know what the image circle is, in terms of coverage? I'm planning on chucking an IMX432 at its tail end along with a 2X Barlow (1.25"). Does anyone know if I might run into vignetting issues? What about a 5X Barlow; would that work also? For night time astrophotography scopes, it's fairly easy to find out sensor coverage. It seems that with solar scopes, this information is slightly more obscure, at least to complete novices like myself.

They're blowing my tiny little mind! I know I don't have to tell you lot that one can spend quite a bit of time just downloading the full res images and taking a little sight seeing tour. Just seeing all those tiny, tiny galaxies on top of the Souther Ring is a sight to behold for more than a glancing second.

Understandable. I mentioned the FC-100DZ specifically as it's under budget (3k sans accessories), it falls under the "long focal length apo" category and Tak make a big deal out of this flavour of FC-100's photographical chops. An Astrobin search yields some pretty good results. My only gripe with it would be that it's a long little doggy at 84cm. With a full image train you'll probably end up with a meter of skinny tube hanging off the mount, and wind is going to be a bit of a factor at that point.

I'll add to @Elp's list: APM LZOS SuperED - 800mm (slightly over budget) Takahashi FC-100DZ - 820mm (yes, it's a doublet but reportedly as good as a triplet) TS 106 FCD100 - 700mm Vixen AX103S - 825mm William Optics Fluorostar 120 - 780mm

Being interested in the very narrow band of H-alpha (with a mono camera) means I don't need to worry about it being an achro. In that setup, the benefits of an apo or triplet would be totally lost, unless I'd plan to use it for night time imaging (which I don't).

Omegon already have an IMX432 based Mono cooled camera available.

Thanks to everyone who replied, I've narrowed it down to two options (for now, at least): €1400 New LS50 B600 - with later upgrades including the focuser and double-stack filter €1800 Used SolarMax II 60mm BF10 - with possible replacement of the ITF if and when it rusts Keen to get your thoughts on which is a better choice.