raadoo

@Alexgc here's my take on your M31.

I often find that it's easier to learn by deconstructing what others have done, so I've also attached the PSD file. It ended up quite large at 829MB, but I didn't want to cheat you out of pixel peeping at the full 24MP 😁

I tried to keep as much of the editing using only Photoshop's tools, so at least these will be tools you're familiar with.

The one thing that I used that's not native to Photoshop is StarXTerminator (similar to Starnet++) to break apart the stars from the galaxy. SXT comes as a Photoshop plugin for added convenience.

22-9-24 Andromeda.psd

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.

16 minutes ago, Lee_P said:

I know right, this is big step! But after getting lots of valuable advice here on SGL, the other "faff-free" options looked like they'd only be incremental upgrades, whereas the RC8 is quite a jump but still affordable. I also feel like I'm maxing out what I can achieve with the FRA400, and want something quite different to give me more headroom to develop my skills. I like to experiment with my imaging, and I'm expanding that philosophy into hardware now. Will it be a successful or failed experiment though, that's the question..!

Currently, I *think* I've collimated the RC8, but haven't had the clear skies to properly test. RCs are supposed to hold their collimation well, so I'm hopeful that once I overcome all the initial set-up hurdles, the faff-factor shouldn't be much more than the Askar FRA400 🤞

I haven't gotten rid of ol' faithful yet! I'll keep it until I've got the RC8 humming along, and even then I may keep hold of it as a grab 'n' go visual 'scope. No definite decisions made on its fate yet!

That's the spirit!

1 hour ago, Lee_P said:

TS Optics 8" Ritchey-Chrétien. A lot more complex to set up than the FRA400, I reckon I still need a week of clear nights to get all the components singing in harmony!

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!!! 😂

1 hour ago, Nik271 said:

Wow, imaging at F12 and 1500mm, pretty good result!

How long were your subs if I may ask?

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!

21 minutes ago, Lee_P said:

OK thanks, makes sense.

Four times faster, I think? RC8 binx3 = 84600; FRA400 binx1 = 19510.

 

OK, let me write my understanding of this binning malarkey and let's see if I've got it:

If I were to use my 2600MC with no binning (i.e. binx1) with an RC8, I'd get an image with a resolution of 6248 x 4176. However, I wouldn't actually be getting useful data across all those pixels because seeing conditions and mount limitations combine to, in effect, "blur" the view. When processing the data, I could binx3. This would make a square of nine pixels into one super-pixel. The plus points of this are that it would increase my SNR by a factor of around four. What takes me 20 hours with my current set-up would instead take five. Or, I could image for 20 hours and get a SNR equivalent to 80 hours with my current set-up. It would also decrease processing time due to the smaller file sizes. The downside is that the image's resolution would only be 2082 x 1392. This isn't that bad though, because the "lost" resolution wasn't useful data. I wouldn't be able to crop in very much with this lower-resolution image, but the RC8's focal length of 1600mm gets me very close in anyway, so that's not a big issue. If I need a wider FoV I could mosaic. 

Is that accurate? The lower final resolution still makes me itch a bit because I'm used to dealing with very high res images (both in astrophotography and regular photography) but I understand that with the proposed set-up it's not really a fair comparison. If I need a higher resolution image, e.g. for printing, I guess I could always use Photoshop's Enhance feature, or Topaz GigaPixel AI, to artificially bump up the pixel count. I just did an experiment doing that with some of my existing data, and it looks quite good to my eye. Enough to somewhat allay my fears about low-res images anyway.

Thanks vlaiv, I definitely owe you a pint! 🍻

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).

4 hours ago, Lee_P said:

 I just want to check I'm getting this right... If I calculate aperture squared multiplied by image scale squared for the FRA400, I get 19,510. For a much bigger telescope -- the Askar 130 PHQ -- the result is 10,177, i.e. 52% of the FRA400's speed. In real terms, would that mean that I'd need twice the integration time from the Askar 130 to get a comparable SNR from the FRA400? It's hard to get my head around, considering the slower telescope has a significantly larger aperture.

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.

14 hours ago, 900SL said:

Having just gone through the same process and candidates, I've decided to get an ES 152 MN. Now waiting for them to arrive in stock. 

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

1 hour ago, Lee_P said:

This is a brilliant list, thanks! I've spent some time this morning looking through them all. I think the two that appeal to me most are:

• ES102CF. This has a good specification, and a like how light it is. Would it need a flattener though? It sounds like it can take a ZWO EAF but longer bolts are needed.
• Askar 107PHQ. This was my original thought for an upgrade and it's hard to shift it out of my head. I hear you about the quality control issues, but FLO bench test all their Askars, which means they should pick up on any lemons.
   
• And the ES MN152 is an interesting proposition that may be the best of all worlds. Maybe hard to get hold of though!

Have you been following the other posts in this thread? It's interesting to hear about the limits of sky conditions and the like, and vlaiv's comments around how there may not be much gained by having a new telescope rather than just cropping in on the images we're taking already. (Although you and I are using different cameras).

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.

5 minutes ago, vlaiv said:

Do include SW MN190 and ES MN-152

There are few high end models from Intes Micro - but no longer produced and maybe only available second hand.

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?

9 hours ago, HollyHound said:

In order of “best lunar view”… ascending order 🤔

C5 - Softest view, dews up fairly easily, however it makes a fantastic, compact DSO scope (especially with a .63x reducer)

Mak127 - Super contrasty and (as has been said by others) quite “refractor like”. Portable and built like a tank, but also dews up and takes a while to cool.

CC6 - Notch more contrast and detail. Excellent focuser and doesn’t dew up. Slight smear on bright planets (due to four vane secondary spider). 

Mewlon 180 - Mega contrast and detail. Doesn’t dew up. Superb optical finder/handle. Very lightweight for its aperture. Takes at least an hour to really cool properly, although quite usable from 30/40mins onward. Less smear due to three vane spider. Slight loss of detail near FoV edge.

As I tend to use the Mewlon in a dual combination with the FC-100DZ refractor, this obviates the cooling issue somewhat, as I use that whilst waiting and then switch for detail.

For me, the Mewlon would be my one “cat” for lunar, although If I could only have one scope, it would be the DZ 😃

Best bang for buck though as a lunar (and planetary) scope, has has to be the CC6 though (it’s a 1/4 of the price!). If I ever had to sell the Mewlon, I would replace it with one of these 👍

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!

3 hours ago, HollyHound said:

I know it's a good few months since this comment was posted, but anyway... It was me that bought the CC 6" from @johninderby and I can confirm, it was a superb (and lightweight) scope 👍 

I only sold it (back to John again of course, as he was missing it 🤣), as I bought a Mewlon 180... any of these open tube designs (Classical Cassegrain or Dall-Kirkham) are fantastic lunar/planetary scopes. I love them because they don't suffer from dew, unlike my Mak127 or indeed refractors.

However, I've also still got both my Mak127 and C5 (SCT) and they make superb, easy to use scopes too.... we truly are blessed to have access to such fine (and relatively cheap) equipment in this modern era 😁 

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?

1 hour ago, Elp said:

Tbh, I don't know if receiving more o3 over affecting ha signal is a good thing, from experience shooting mono o3 signal is usually much weaker than ha (subject to target) so you wouldn't really want this. Using an osc camera any received narrowband signal will be further hampered by the rggb pixel layout.

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.

3 hours ago, George Sinanis said:

I was looking a a month or so ago at the Antlia. Any idea where to buy from?

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.

2 minutes ago, Dinglem said:

at least the images were worth seeing 😀

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.

5 hours ago, Elp said:

I refrained from adding a Tak as it bumps up the price just by mentioning the name... Same price territory as Borg though.

On a other note though personally I've found an added second scope is usually a different type, first it was a Newtonian for the aperture and FL, then an SCT again for the aperture and FL in a more compact form.

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

1 hour ago, newbie alert said:

The lunt is only a achromat

Yes you can cause irreparable damage to your eyes/ camera if you don't follow caution... But then again you can by just staring at the sun..

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).

On 16/06/2022 at 20:13, wimvb said:

A cooled version of the 432 would be a very nice galaxy camera. 0.9”/pixel @ 2 m focal length. I like my cooled 174mm. 😄

Omegon already have an IMX432 based Mono cooled camera available.