pipnina

15 minutes ago, fullmoon said:

I did consider that scope before I purchased the Explorer, but it just wouldn't suit my surroundings ATM.

I think I need to get out to an astro club and have a look at stuff 1st hand. Maybe it can help manage my expectations as well as give some valuable experience. 

I take it the EQ mount is providing you with extra necessary height then?

In such a case, if you find in a few more weeks or months (depending on how often you manage to keep observing in that time, clouds and all) that you still very much enjoy observing but find this scope and its wobbly mount frustrating: You could consider doing what I did and upgrading to a 250mm or 200mm dob, which would have more height than the 130mm dob

You can also in theory put a block of wood or somesuch underneath a dobsonian to boost the height.

At the end of the day if you know a tripod mount is best, I won't ague with you, but I do personally quite like the dob format for its cost & rigidity.

An astro society or club visit would be a good idea!

I had this exact setup when I started in 2014, I know exactly why it's frustrating you! Carrying it around led to being poked and prodded by all parts of the mount...

I switched it up by moving to a dobsonian mounted scope, and I notice that if the AZ4 is on the table as a mount switch, you could buy a skywatcher heritage 130 dob for the same price, if not a little cheaper.

Dobs I think are much more rigid against touching the ota and against wind, vibrations are less noticeable and settle faster. Even my chunky HEQ5 EQ mount wobbles when I touch the focuser of my frac.

Hope you continue loving your scope!

44 minutes ago, AstroMuni said:

I will second that. When I started on this journey, the fact that I didnt own a DSLR helped me be less biased to one or the other. Once you realise that the sensor technology is the same in DSLR & Astro cameras & that the sensors in Astro cameras are more sensitive, then it helps in making the decision. 

Strictly speaking I think many of the new CMOS astrocams are the same as the astrocams sensor wise. Many astrocams literally use the same sensor as a consumer camera on shelves today. The difference comes from the amplifiers (don't see many consumer or even professional mirrorless/DSLR cameras with 16-bit ADC...), and the software in the onboard computer, plus the absence of ir-filtering sensor windows.

For all intents and purposes, a new mirrorless camera from sony would perform the same as an uncooled ASI2600MC without the ir filter and dodgy processing done onboard, sadly the consumer cameras are insistant on things like raw file tampering (mistaking stars for hot pixels), so even if you modify them they still come out lesser than the 2600MC will.

I think the difference between CCD/CMOS astrocams and DSLRs was more prominent however, back when these sensors suffered from much more noticable dark current and brighter hot pixels. Even if I don't cool my RisingCam 571, and it runs as +5 or even +10c, I don't notice any intrusive dark current like I did with my old Nikon D3200. Strong dark current in older sensors paired with a lack of cooling I think makes the bulk of the older DSLR's struggles with astro.

Now of course, a lot of people are using these cheaper uncooled zwo cameras with a good deal of success and not seeing much dark noise at all.

I do feel like traditional camera makers COULD demolish the current astro camera makers with simple changes if they wanted to, like having a pure-raw setting (zero software involvement or post processing) and having the IR filters cutoff point moved to say 680nm instead of 650, which as I understand is just a holdover from the film days where you needed to make the film insensitive to deep reds so you could see the film you were processing during development?

Maybe the 533mc  or 585 would be a good starting point for Astro74? Low noise, high QE, dark current is relatively low even in outdoor summer temps (around 20c at night in the uk?). And also very cheap (by new camera standards)

https://www.firstlightoptics.com/zwo-cameras/zwo-asi-533mc-colour-usb-30-camera.html

https://www.firstlightoptics.com/zwo-cameras/zwo-asi-585mc-usb-3-camera.html

12 minutes ago, ollypenrice said:

Fair warning: I'm often a lone voice on this topic but I always say, Absolutely not a DSLR unless you are cash-strapped. If you can run to a cooled astro CMOS with a reasonably sized chip, then this will roundly beat a DSLR. It will need a PC so, if that's a problem, forget it. On the other hand, managing capture with a decent sized preview and focusing aids makes life far easier. In the days of CCD the dedicated cameras were way more expensive than DSLRs but now, with CMOS, astro cameras are both better and cheaper.

Olly

I was skeptical about this the last time the topic was brought up but I feel like I am much more inclined to agree with you now. Many of the smaller sensor zwo cameras are actually very capable even without cooling, and can even be price competitive with modern mirror less cams that aside from sensor real estate will produce worse images... I can't remember the model numbers exactly but I think it is the ASI 533, 585 ETC that are uncooled, a bit small but don't break the bank and have good sensitivity and noise characteristics... Despite the idea of wasting imaging circle area by not being able to record it, after thinking about it, your simple statement of "4x sensor area doesn't mean much if it's four times as much rubbish" has pretty much won me over at least.

As you say as well, astro cam costs have plummeted at the low end while quality has shot up.

The only thing I'll say for you Astro74 though is that I can't recommend trying the zwo120 for deep sky, as it really is only geared up for guiding, has poor noise compared to other cams, and at a gain level where noise is not at CCD levels, the full well capacity is well below 1kev, whereas most of the other cams like I mention above I think have lower read noise and full wells around 10kev+ at those low noise gain settings. Much easier to get a clean picture without having to

12 hours ago, Astro74 said:

Hi I’m venturing into AP and would like to know if I’d be better with a dslr or an Astro cam like a Zwo 120 ? 
 

if it’s a dslr - which one would be best, I’d like something simple and easy to use Jo too high tech 

 

thanks 

resort to super short exposures.

Also, I can't seem to move the quote block on my phone, so I guess it lives there now haha. Sorry!

Hubble Space Telescope: It is the source of all those pretty pictures whole generations have grown up seeing as THE bar for quality. Plus it allowed us to see back to near primordial times in a cosmological sense and continues its primary mission of observing and measuring extra galactic supernovae to this day, over 30 years later! Plus it was put into orbit in a space shuttle, one of the coolest things to ever fly.

VLT: One of the first observatories to use a laser guide star system for adaptive optics, and THE best interferometer used for astronomical purposes. Besides being a technical marvel and living breathing science and technological development of the most impressive order, it also pinpointed the exact location of the black hole at the center of our galaxy and constructed an image of betelgeuse with surface detail!

Arecibo: aside from simply being massive and cool (the dome was a 5 story tall building by itself!), the telescope's ability to perform active radar imaging of asteroids was pretty unique and cool. It also captured the minds of many.

16 hours ago, bosun21 said:

Can’t you just put a piece of tape over the wide field camera leaving the 50MP one to capture the image?

Oops, when I said widefield camera I kinda meant the "main" camera. I guess I used that because the pixel6 pro has a telephoto periscope camera so the main cam is very widefield in comparison (I think about 6mm FL)

To be honest from my experiments, the actual 0.7x widefield cam is even worse than the main cam. In low light performance the difference is honestly very dramatic.

9 minutes ago, vlaiv said:

Do be careful - there is spot just before perfect focus that focuses on disturbance in our atmosphere rather than planet itself - if you focus on that - you will see actual air - much like warm air over fire - distorting the planet. You don't want to focus on that - try to focus on actual planet, but do understand that atmosphere will make it difficult as everything will dance around more or less (depends how calm the atmosphere is).

I didn't realise the turbulence and astronomical objects could be at different focal positions! I guess I imagined it would all be at too high an altitude or that turbulence would affect the image whether it was in focus or not.

I guess it does bring back an interesting tidbit: Apparently most of the turbulence on an average night comes from within 10 meters of the ground, I believe that was on some observatory's website but I cannot remember now.

3 hours ago, ollypenrice said:

What do you need this torque for, though? A balanced mount offers very little resistance.

Olly

Whoops, I got my mind muddled up and quoted you instead of Vlaiv, who actually did mention step-skipping (which is usually a result of insufficient motor torque)

To that end, basically stronger motors would mean skipping fewer steps, which would mean better guiding/slewing if the mount is struggling on either.

On 16/06/2018 at 08:54, ollypenrice said:

Vlaiv is perfectly correct that the round stars test is almost meaningless but at least with round stars you can produce an attractive image. When setting up the first Mesu we always had round stars but by tuning the guide parameters they got smaller and smaller!

I don't think there's any reason to believe that the HEQ5 is less accurate than the 6 provided both are within payload.

Any backlash adds to the guide error and the worse the seeing the more it does so. (When corrections are few there is a reduced tendency for the mount to be sent oscillating across the backlash.) So losing the backlash is a very good idea. The other ways to combat backlash are to run slightly east heavy and slightly polar misaligned. East heavy keeps the drive in 'push' mode and the misalignment means you can disable guiding on one direction in Dec, letting the other 'push in the direction of correction.' This does work and won't stop you from doing 15 minute subs.

The duration of guide subs is also something to tune in the light of prevailing conditions. Our EQ sixes thrive on short guide subs if the seeing is good because they have pretty rapid PE. However, if the seeing is bad this has them chasing it, so we do better with longer subs which average out the position of the guide star's image. (It's worth remembering that the guide trace has no way of knowing where the real star is. It only knows where its image is. So very short subs do give a better trace but is that a trace of the real star or just its image?  Curses!! )

The other variable within the guide trace is the position of the scope between corrections. Again we have no means of knowing, but Avalon claim that with their backlash-free belt drive the correction is fed in faster so that, between guide inputs, the true location of the scope is on target for more of the time. With any backlash oscillation in play it's a good bet the situation between inputs will be worse.

Olly

I know this is a bit of a long gap for a reply, but I did some maths only a month or two ago to work out how much torque the heq5 can produce at the driven shaft. When run at 1/64 microstep I think it came out to around 0.24nm. about as much as I could apply to a 1/2" socket drive on my workplace's torque calibration machines with my finger and thumb.

So all in all rather poor torque for a 705:1 gear reduction!

You can increase torque by reducing the microstep ratio but it's not linear, maybe mods could improve the heq5/eq6 mounts with inexpensive higher torque motors hmmm

Working on my processing since my scope isn't in top shape right now. Having a fiddle with StarnetV2 in Pix. After many hours of headscratching trying to install the thing (turns out it won't even show up if you use an AMD CPU, unless you get an alternative tensorflow library that isn't compiled for Intel's AVX-compatible CPUs)

So I try a recent image of the Pleiades, and at first it seems quite good, but when I look at the image a bit longer and the star map, it seems the brighter stars are... Not handled so well.

At first this doesn't look so bad, but then...

It seems like the bigger stars don't really get "saved" in the maps, and even in the starless version one of the big four stars is only mostly removed.

Do I need to do some other work to these images before I can run star removal? Or tidy up the star-removed version and the star map to make it look good once re-combined?

Second example, where it kinda worked a lot better:

Obviously removing the stars from this image worked very well, the ABE+stretch-only version (left) looks way more crowded and it's harder to see the IFN in the background compared to the starless-processed version. The starless processed version looks cleaner, less busy, sharper even.

But zooming in, it's not exactly perfect, so maybe I still need to clean it up a bit?

I'd love to hear some tips abut using this tool, as I feel like mastering this new trend in astro processing is going to totally change the outcome of my images if I can get it right!

Thanks and clear skies!

I've been thinking pretty much since I first saw the ZWO one in stores: What scopes can actually support these monster cameras?

I imagine something like an RC in sizes above around 16" could do? I don't know of any newtonians that could cover a sensor of that size, or any coma correctors that advertise anything beyond 35mm. Maybe some premium triplets with very large flatteners can pull it off? But then I saw a post recently about the M82 sized riccardi flattener not correcting for one of these medium format sensors...

Also, I'm slightly annoyed by manufacturers calling them medium format, when the last format to use that name (film) was *much* larger (60x60mm or 70x60mm even!) Large format is also taken by the film plates measuring 5*4 inches.

I am quite excited to see these big sensors coming down in price however... Maybe when sony's next gen of sensors come out we'll see them come down again! (ha). Companies like Fujifilm have had these sensors in much much cheaper mirrorless formats for a while (think £3000)

25 minutes ago, FLO said:

In fairness, your Esprit-100 is around three years old and the pinching is so very slight, we advised you it is not worth trying to correct it.

All telescopes, if you look hard enough, have an aberration of one type or another. None are perfect. 

We offered to send it to Es' because we can tell it is upsetting you, you purchased it from us (the TS-Photo & 130mm f6.6 were not purchased at FLO) and we like to help. 

I don't know where that figure came from. Not us. 

The cost of collection, delivery to Es, and then collection and redelivery to the owner is normally around £30. 

If Es thinks he can sensibly improve the aberration - he will.

He charges £75 per hour. Most adjustments are made within an hour. 

At FLO we are charging only what it costs us (Es' charge and courier costs). We are not profiting from this situation. 

@pipnina Your glass is currently half empty. It happens to all of us at one time or another. It is like the weather. It will pass 🙂 

Best wishes, 

Steve 

My estimate for two way delivery was based on how much it cost to get it to me when I bought it: £57, plus some padding because when costs aren't 100% certain I tend to try and imagine it's more than is perhaps realistic. I realise now i made it seem like *you* quoted the postage price, when actually it's my own estimate, whoops... If parcelforce (seemingly Mr Reid's preferred courier) charges less than DHL then that's fine my me. I will be honest I had realised I did not clarify how long corrections can take (I worry a lot about mis-handling social requests, with the ASD and such). So I wasn't sure if I'd be paying for one hour or ten, for example.

You, and others in this thread are most likely right, I am likely being a bit pessimistic, but not without having been worn down a bit first!

I can only thank you guys at FLO for your help, as I've been directed to a fair few helpful pieces of advice and purchases via contacting you by email.

Your service is why, the only times I've bought something astro related anywhere else- is because you don't stock it or I couldn't afford buying new.

Thanks again for forwarding me to Mr Reid in this matter.

On 26/12/2022 at 14:48, Knighty2112 said:

What grease did you use to replace the grease already in the HEQ5 Pro? Thought about doing the Rowan mount upgrade on my mount, but as I only do visual then not sure it will benefit me much. Might have a go a re-greasing it though. 

I believe the HEQ5 uses a lithium grease normally, I'm sure other greases will work as a substitute but I would probably choose to go with the manufacturer's choice myself, unless there's an obviously better alternative.

Lithium grease is quite thick but of course that can be quite good for the slow, high torque and high load gearing being lubricated.

1 hour ago, edarter said:

Happy to do that, though the file is rather large!
Thank you, I'm very happy with it, just never satisfied lol! Have finally come round to the idea that I really need to chop the focus tube on the 130PDS to get rid of those bl**dy  pacman stars! Something for this weekend maybe.

File can be found here(FITS rather than TIF, hope thats ok):
https://www.dropbox.com/s/amcmgxly9zgbtwf/Triangulum_Galaxy-session_1_session_2_session_3_session_4-NoSt.fits?dl=0

Sadly my idea didn't work 😕
I tried to reduce the larger detail levels int he galaxy so i could try and boost the areas where ha would be, but I couldn't isolate it much at all.

Also looking at what you started with, I can see you really know your way around editing your photos!  I was really struggling to get a background or colour anywhere as clean as yours.

5 minutes ago, edarter said:

Just thinking about this a bit more - is there anything I can do by splitting the channels and boosting red somehow? I know its a bit of a cheat but just curious as to what the possibilities are other than gathering HA data.

Would you be able to share the unprocessed stacked tiff? I could have a fiddle and see if an idea I have could work out for you

Your image looks very nice already though I must say!

1 hour ago, ollypenrice said:

Difficult one. It rather sounds as if the scope is a lemon, though Es Reid might be able to fix it. Will it really cost £150 to send it each way? That seems like a lot. A compromise might be to get him to make an initial assessment of what's likely to be possible.

I agree with Tomato regarding pixel-peeping for stellar perfection. How bad is it? Do you see it if you don't look for it? Like Steve, I'm using a RASA 8 and also, now, a Samyang 135 F2. I've never enjoyed imaging so much in my life and I'm able to make the kind of pictures I've always wanted to make. Not surprisingly, it is very hard to achieve stellar perfection in these gloriously fast systems but does it matter?  If it's OK to have darned great crosses springing out of stars, why is it such a big deal if small ones round the edges aren't prefect if you look closely?  (Large, imperfect ones can be fixed in one click by a simple Photoshop routine saved as an action.)

I also think that, sometimes, a product really is born a lemon. I know one imager who had a lousy new Paramount which it took him two years to get working, by which time he'd switched to a different mount. He reckoned it was now OK and sold it to another imager I know. It isn't OK, it is back in 'not working' mode again. This is made worse by Paramount's hard-nosed attitude to customer service and the absurd prices they charge for components. The same applies to another person I know who got stuck with a very expensive and very unsatisfactory OO UK astrograph. There is a case for cutting losses and bailing out, I guess.

Olly

I understand that line of thinking, and maybe I am stressing over it too much... But I also know at heart I am a pixel peeper and even if other people might look at my images and go "oh that looks nice!" I'll still know what's "wrong" with it and will struggle to be satisfied!

As for diffraction spikes, I rather like them in all honesty in reflector images... But only so far as I could keep them sharp and defined, and they didn't encroach on the image or sit at angles other than increments of 45 degrees. It sort of gives a hubble-esque look to me and I think the mirrors scatter a little less light than lenses, leading to bright stars bloating a bit less in a reflector which makes up for it a bit in my mind. Still, at that point it's an artistic choice as much as anything! Coma in the field center and astigmatism at the edge isn't so easy to debate over. Like you say though, everyone has their tolerance and tolerances can change over time...

10 minutes ago, Adam J said:

Can I see your latest image so I can see what your looking at?

Also if you have any star test (intra and extra focal) that would be useful. 

Can only really give an opinion after doing that. 

But what I would say is that the general rule is that if stars look ok in the centre of the image then its probably just needs some TLC.

Adam

Best I was able to do when it came to star testing was this:

Not easy to take pics with a phone down the eyepiece haha. Some also said I might not have been far enough away, although the 0.05mm star would have had a radius almost half that of the Rayleigh criterion for the scope at that distance so it might have been an ok test.

I have now been in contact with Es Reid, he says he can take the scope on if I send it late next week (was busy this week and into the next). I think I will send it after all, the only problem being that he is in Cambridge and I am in Plymouth!

I trust parcel force (the courier he says he prefers, he said Post Office specifically but I think PF are the only courier through them that will take a telescope) to get it to him ok, but I don't know if I trust any courier to be delicate enough to bring a tuned and checked refractor back to me afterwards...

A train trip to Cambridge and back might be in my future to feel safe here.

He did say scopes like mine can lose collimation easily and are very sensitive to de-centering... Which does make me worried about holding onto the scope for too long after tuning... Might be reinforcing my purchase of a 365 cover and pier/permanent setup plans. Telescope can't lose collimation if I never take it off the mount, at least save for high winds.

27 minutes ago, iwols said:

just wondered when using my rotator do i need to retake my darks flats bias frames? thanks 

Darks and bias frames will be fine

Flats need to be retaken every time you move the camera or the dust bunnies shift around.

I have heard that dark frames expire after a while, as the camera's dark pattern slowly changes over time. I don't know how true that is but I don't use darks personally.

4 minutes ago, Elp said:

I think we all go through it to some degree, maybe not in an avalanche sort of way you have unfortunately experienced but usually the passion takes front and centre view and we continue regardless. My struggles at the moment relate to flats and background extraction JUST NOT WORKING and the new asiair update effectively rendering my asiair pro useless (two nights in a row I setup from scratch and put it away again as it refuses to respond and goto has a mind of its own). So more time and investment into investigations, all the while whilst loosing valuable imaging time.

If it were easy, would we do it?

Funny enough I also have those same flat/extraction issues, and given as it's happened on three different scopes I'm starting to think the problem lies elsewhere haha. Probably in my case I need to fully nail the calibration (flatdarks, bias, etc)

Software updates have plagued me too, Kstars has had improvements but some releases have been broken and I've had to wrestle the ubuntu package manager to get the old one back!

5 minutes ago, Clarkey said:

I really feel for you. AP is hard enough without the issues you are having. I also feel very lucky - the week before you purchased your scope I brought a second hand 130mm triplet in the SGL classifieds. When I saw your scope come up I felt a bit of envy at missing out. With hindsight I missed a bullet. If it makes you feel marginally better, I sold the 130mm scope a few weeks later as my observatory was about 5cm too small.

Unfortunately, I don't have any words of wisdom to help. Given how much you have paid out already, it is a real quandary. All I can say is I hope you get it sorted.

Just out of interest, what did the seller have to say? They must have been aware of the issues with the scope.

The seller used a much smaller sensor camera, and I suspect this is a big part of why they didn't notice. I did speak to them about it but they seemed fairly sure it worked when they had it, and the pics they sent taken with the scope before I bought it looked ok, in the end maybe it was bad when they sold it, maybe it wasn't! In likelihood it probably was in at least some of the ways described, but it's a bit far gone now to go and complain haha.

Thanks for your best wishes also.

2022 was a year of some decent highs and painful lows when it came to my astrophotography ventures. I made the dive from an unmodded DSLR on a handset-only HEQ5 with a 130-PDS, to modding the DSLR, then replacing it with an astrocam and using my laptop to control the setup. Then I broke my PDS (cut the focuser abrrel too short when trying to prevent it from intruding the light path), and replaced it with the horrible TS-PHOTON. That plagued me for 2022's summer and set me back over £900 once I dealt with dovetail bar upgrades and coma corrector upgrades on top of it.

Then when I was at peak distress with the PHOTON that would not hold even secondary collimation at this point (took the secondary out to blacken the edges, when it went back in, it wouldn't stay in one spot...) an ad came up in the classifieds here. 130mm f6.6 carbon tube triplet. For 1500 including a 0.79x corrector. In theory that's not just a good deal, but ideal timing for me. Some discussion with the seller and I wind up buying it, and it goes via DHL and turns up at my house a few days later.

First night I get to try it, I can't get the corrector to work, massive astigmatism at the edges (later turned out it was my fault, backfocus went down by 6.5mm due to no longer using a M48-T2 adapter). I took the corrector off and realised the focuser was tilted, and not in a small way. And on top of that, the focuser slipped when my ZWO EAF moved back and forth, and even slowly slid out during the night... It needed changing. After bribing the machinist at work with a box of Celebrations and cutting the rear flange off of the telescope to make it accommodate ANY alternative focuser, I was now down £2050 minimum, but I had a 3" R&P with tilt adjustment instead of a rubbish 2" crayford instead.

But the images still weren't right. Even dialing in the corrector's backfocus more accurately I realised there was astigmatism on one side and coma on the other, and a bit of coma in the center of the image. The front cell was mis-collimated.

After googling and researching and buying an artificial star testing kit, I used my highest power EP to study the center of field star pattern for an afternoon in daylight. I thought then that there was a little astigmatism in the middle still, but hopefully it was improved as the tilt of the cell had now eliminated the off-center rings. Yet the next time I went to image, it was unchanged. Something more drastic is wrong and it's beyond my capacity to correct. If I want to fix it now, I need to send it to a specialist. I contacted the people at FLO and they have forwarded me to Es Reid, who I will be contacting shortly. But they warned me that the *minimum* I would be charged would be £75 per hour, plus the (based on my estimates) £150 needed to post it to and back.

Now I am torn. Is it still worth me going through and spending yet more money on this refractor... Or am I just getting trapped in a sunk cost fallacy, and this scope will just cost me more and more money, never being as good as it could have been if I just splashed £3500 on a 120 or 130 triplet straight from FLO which was already checked by Es Reid as part of their running agreements... And saved myself months of stress and DIY and most importantly, NOT IMAGING.

I feel like I need this off my chest, just because at this point it's genuinely eating into my life because of the sheer emotional, financial, and time investment I have sunk these last 12 months.

Hope all of you are having a better time!

36 minutes ago, newbie alert said:

Are you sure you have your spacing correct, stars pointing to the center indicate that you need more

I have been tuning the spacing but since the star shapes are different in each corner it's been hard to get it exact.

I will have the chance to test it tonight so hopefully I will know if the tilt is now correct and will be able to dial the spacing in a bit better.

29 minutes ago, Louis D said:

Make sure the triplet is fully acclimated.  My 90mm triplet takes over 30 minutes to acclimate just 11 degrees C.  Until then, I see all sorts of star spikes.

A good shout. I have been keeping it outside for a while now as the weather is ok and it is protected from prying eyes. So it should remain decently acclimated to the temperature

The biggest issue as mentioned will be creating the threads. There are a few things that all need to be parallel or concentric in a filter wheel so it might not be easy to print.

Given as a good LRGB filter set will set you back at least £400, and a single quality 3 or 5nm narrowband filter will set you back 300-500 (thinking about 36mm size here), I think it's probably not a great place to look for savings sadly.

Still, maybe money isn't the point- perhaps it's the challenge and seeing if it's possible regardless. In such a case: off-the-shelf bearings and bright steel rod could make a decently sturdy center for your filter wheel's rotating part with minimum run out. Might be a good starting point?

I've done some fiddling with it in daylight and I think I've solved the coma issue in the center. But now that that's solved I think I've introduced astigmatism... or worse, it's there when the cell is properly tilt collimated, meaning the problem lies within the arrangement of the triplet of lenses within... Far beyond my ability.

Hopefully this makes it better when imaging however, will report back if it is or isn't 😬

I have my artificial star torch (5 holes, 50 micron, up to 250 micron) and I'm looking at the smallest one in my 6mm eyepiece at a distance of about 13 meters (800mm focal length, 130mm triplet of unknown make and design).

As I adjust my focus from intra to extra, I notice that when it's focused it actually looks quite good, intra focal it looks like two strong rings concentric with the white dot in the middle... but the middle isn't well defined. it looks strong, but it also almost looks like three dots split up. Not sure if that's pinching or if it's miscolimation or something else! When I'm extra-focal, I see rings moving into one corner of the outermost ring, which seems like coma (cell misalignment) to me.

Should I be basing my adjustments of the tilt of the main cell on the extra focal value? Thanks

Here's the best pic I could get down the eyepiece extra-focal, sadly intra focal wasn't possible as getting the phone into position was very hard indeed and the stars were a white-out!

And this is what I'm seeing in images (albeit with corrector, but it shows that star shapes are not uniform across the field)

I have performed the paper-with-crosshair check over the front of the scope to align the focuser with a laser. And because I have tightened the grub screws holding the focuser that is now rock solid (can't use the rotation feature though now)

Should I adjust my cell with this artificial star setup, do I need more magnification, am I reading things right (that extra focal view is showing me the coma error?)

Many thanks!