pipnina

Could be the front cell or the focuser aren't quite done up tight? I've had that issues before...

Something about this reminds me of a very old post here, I think by @ollypenrice looking for some sort of "andromeda shelf" that was not confirmed at the time but someone had claimed to detect. Could this be the object in question?

Personally I've based my opinions around printing materials on this guy's tests: He tends to do a variety of tests that show tensile, impact, and other kinds of strength. So in general I feel it's good enough for us amateurs!

I found it rather hard to design a newt in the online newt calculator tools that had good illumination across a good FOV, plus by removing the 90 degree light path turn you make it easier to baffle the tube and remove stray light from entering from the side of the focuser. It's also just something interesting to work on regardless haha. A fair few correctors work with f3 mirrors which would be quite a good setup, something like a 10" or 12" F3 mirror and camera style focuser might be a bit better regardless of not exactly being a RASA. But if I find like you did that it's not all that, I won't have spent much money to find out!

For now, I think I can only print with PLA anyhow as ABS requires a warmed containment for the printer to avoid warping, and PETG/Nylon etc filaments require hotends that run much hotter than my Ender3 can handle (above 235c I think is unsafe as the hotend has PTFE tubing running all the way up to the nozzle, which fumes up and can even burn above 240c) PLA+ seems "stronger" than normal PLA, but only because normal PLA is very brittle, while PLA+ tends to accept a lot more bend. I think tests do show normal PLA to take more force before total failure however. I expect creep to be the big problem here. A test part I made for a catflap cover has warped and all I did was leave a plate on top of it. I am thinking that steel spiders might be a necessity, but the holder for the focuser seems rock solid even with this PLA+ so I don't expect to need to change that material. I am planning on making the spiders out of plastic first, and attaching them to the focuser holder and seeing what weight they handle. I may put some weight on them and wait a few days, see if they move... I also plan on making them quite tall, as I think they can be any depth without impacting the image... Not 100% sure about that though. I always assumed only the thickness impacted diffraction. I guess eventually i'll find out!

I had been thinking of this for a while, but until I got my 3D printer it was a bit of a non-starter. Learning the ins and outs of printing and using FreeCAD has been quite challenging, but last night the first "finished-looking" prototype for the focuser-holder for my newtonian conversion came off of the build plate! And it fits very nicely. My next step is to design the way to support it. EsunPLA+ may not be strong enough to support several kilograms of camera and focuser, so I may have to look into a hybrid approach with sheet steel vanes fixed into the PLA supports... Work ongoing! For now, i'm happy I managed to design and produce a working holder for the focuser. While I could have bought a 2" rotating focuser as suggested by @vlaiv, which would reduce the obstruction and weight, I wanted to see what the minimum conversion cost would be for someone who already has a printer, so replacing the focuser isn't my intention at this time. I intend to post more updates in this thread as my project progresses. And eventually find out if it's a worthwhile re-configuration for newt imagers! So far this setup gives a central obstruction of 95~ mm diameter. Which is about 2-3mm more than the obstruction created in the RASA8's optical train. Perhaps I will work on a way of removing the focuser adjustment knob and replacing it with a printed part that can be slid on and off the shaft so it need not interfere with images... Thoughts welcome!

Thing is, my 24mm I think has LESS relief than my shorter EPs! Both the Vixen SLV and Stellalyra UWA have 20mm whereas I think the maxvision is around 17 or 18. Yet the shorter lengths feel harder to use somehow.

I don't know if it's just me, but I've noticed that even the medium-to-high quality EPs I have seem to be rather challenging to observe through. For instance, my vixen SLV 10mm and stellalyra uwa 6mm both seem very hard to get a proper look through. I find as I get closer to the eyepiece, the field of view widens, but by the time I get close enough for it to widen to above say 40 degrees afov, the edges blacken as if I am now too close? For my maxvision 24mm/82deg EP, I find it's quite hard to see the edge of the afov too, but I can definitely see much more of the afov in that EP despite not having as much eye relief as the 10mm and 6mm, it also lets me move my eye around much more than the other two, which seem very fussy about my eyes pointing straight forward all the time. Could it just be that the small exit pupil makes them more challenging, the EPs genuinely aren't as good as I thought they were (mismatched expectations) or maybe the clouds have gotten me too far out of practice haha. Am I alone here with this struggle? I'm not a newbie by any means but I do seem to be struggling.

Something I noted was that PHD would fail to calibrate if too close to the north pole. Because 60 seconds of RA movement covers a far smaller star movement at +80deg DEC than 60 seconds of RA movement at +60deg DEC. What was your target?

My small 130PDS did very nicely (with the exception of its known design flaws, primarily the focuser tube protrusion). But of course this is a fairly small scope compared to what you're thinking of, it still did nicely on small-ish galaxies: I also used a scope more in the realm of your considerations: A TS-PHOTON 200/800. That made nice images... When behaving. It also seemed to suffer more from not producing a flat background, maybe the tube walls were not black enough or somesuch. It also NEVER kept collimation, it required modifications to be usable at all for imaging as the collimation shifted just by changing where the mount was pointing... I also never got it to dial in perfectly, all of my images with the scope have some coma or astigmatism somewhere. The images I *did* get, I was mostly happy with. It wasn't easy to gather them though! My advice: If buying a smaller newt, go cheap and do things like put flocking material on the inside of the tube and blacken the secondary edges. If buying a bigger newt (i.e. larger than 150mm) you need a more expensive model to have any ease of use. For some reason the step up from a 5/6" mirror to 8" increases the hassle involved massively unless the scope is better mechanically designed. Good luck!

That's pretty shocking! I bought an A3 paper sized £35 panel from amazon intended for artists to illuminate their paper/canvas. It isn't perfectly smooth but has allowed me to take good flat frames, on my DSLR it was spotless, leading me to think irregularities with my flat calibration are more to do with my astrocam or telescope optics rather than the flat panel. How "proper" astro companies can sell something that is less relaiable than a random cheap amazon purchase, for 5 times as much is beyond me...

I suppose in PI you might do background extraction before the fit? I don't know, I tried it but maybe some small residual gradients were left (the scope was a bit dodgy in that regard)

I've noticed it can be a bit dodgy though- assuming it's valid for use in mosaic images. I could often get two images to linear fit together, but quite often when you stretched the merged linear-fitted images, one would get a black background before the other anyway... It also couldn't handle one of my panels that accidentally had 768 offset instead of 0 (before i knew what offset to actually use). Linear fit just could not correct that and i got my python-coding friend to make a script to just subtract 768 from each pixel of a fits file, which did work. Sadlly the mosaic was impossible for me to complete regardless as I couldn't balance each panel's brightness... Not sure why linear fit wasn't working. I even tried the DNA linear fit script too I believe.

Orion Optics make the CT8, which is f4.5, carbon tube and still cheaper than the vixen, I have hard of people getting good results with these, but I am not an orion optics connoisseur so sadly I can't give first-hand impressions 😕 I have looked for the vixen and it seems like it could be out to cost you about £1600-1700 already, so the Orion option is most likely cheaper. The TS I can see is probably more expensive as you say however, but from what I hear the TS ONTC scopes and the Orion AGs are about as good as it gets for newtonian imagers. IMO it's a choice between the vixen, which you know will have excellent optics and rigidity but also have very very chunky diffraction spikes, against the more expensive TS ONTC and the cheaper Orion CT. I might be missing a brand somewhere but afaik mid-high end newtonians are actually not easy to find, but the budget/low-end market is flooded. Also: In theory the wynne corrector will work with any newtonian, as they all have parabolic mirrors, and as such are all the same shape, if the diameter and f ratio are the same.

I have looked at it myself before and seen a lot of people complain about the super-strong diffraction spikes (you can see in the pics of the scope that those spider supports are very thick!). But if you like strong spikes you might consider that a positive. I think vixen are quite highly regarded so the optics are likely very good. However: I don't have much more knowledge about them sadly as it's not a popular model! I do know that the TS carbon tube scopes are highly regarded for imaging: https://www.teleskop-express.de/shop/product_info.php/info/p6119_TS-Optics-8--f-4-ONTC-Carbon-Tube-Newtonian-telescope---fully-customizable.html A bit expensive though, but I don't know how it compares in price to the vixen. I would personally avoid reflector greater than 6" unless they're of a premium (vixen, TS ONTC, etc) as my own experience shows they do not hold collimation at all. My 8" TS PHOTON was atrocious, but my cheaper built 130PDS was rock solid, for example. Hope you find the one that's right for you, and I hope this helps!

Indeed! The focuser i took from the side of the scope has a square connection that is only 75x75mm already. The diagonal in the scope is 70mm minor axis too, so I shouldn't be seeing too much increase in obstruction!

Certainly the mirror cell for this scope is of poor design. I had to use the technique Alacant told me where you remove the mirror, put silicon sealant on the cork pads, and let the mirror weight squash it down. Before, the mirror would slop in the cell and the collimation would move when tilting the scope in the mount. If I did up the brackets even a little, the issue persisted but then there were signs of pinching. So sealant it was. It doesn't hold colimation either, I had to adjust it near every time I moved it, which was not the case with the cell used in the 130PDS, which held nicely even if i moved it. The rotating focuser might be a good idea though, but maybe only if my initial attempts at getting it to "just work" go well first! I need to devise a way to keep dust out of it too while I'm at it, as the dust cap it came with won't fit after the new bits im designing go into place, and there's a hole where the focuser USED to be. It's already got stuff on the mirror (a healthy coating) so I will need to break out the cotton buds and clean water before I do an optical test! I am thinking about how I will do the focuser-tilt adjustment though. I have a CAD part for the focuser and its 230mm diameter curve to sit on and be bolted onto, next I need to design the tilt and then the spiders it will attach to. Then likely re-deisgn and re-print in matte black when my current first spool of white runs out haha. This 3D printing business is a lot of fun so far, I could definitely see myself annoying my family members with yet more machinery and equipment in the house haha.

Since we're talking about budget achromatic scopes here- I figure this might be a good time to mention my plans to revive my 8" TS PHOTON. I have gotten an Ender3 3D printer this last week and I've been dialing it in and getting to terms with the CAD -> Slice -> print process. I have plans to replace the secondary mirror in the photon with a 3D-printed support for the 2" focuser- turning it into what I think is called a "camera newtonian"? Although Sir Isaac created the design that used the diagonal, so maybe his name shouldn't be attached to it. But on an 8" scope the obstruction shouldn't be too severe, and as long as my prints are strong enough the flex shouldn't be bad either. I might need some chunky spider vanes though... In such a configuration the collimation might be a little easier, as only focuser tilt is consequential and primary collimation (while not EASY on the PHOTON) should be able to make it a nice fast design with minimal/no vignetting, as the focuser and diagonal lost a lot of the light in the original design. If it works as-is, I may get a corrector that reduces the FL and have a "poor man's RASA8" haha. I am sure reality will catch up to me however...

Compared to other AP scopes, I think the 300 I spent on my 130PDS + Baader MPCC was pretty budget! The mount (HEQ5) cost more than twice as much in 2017 prices, and I don't think the HEQ5 can handle too much more than the 650mm fl / 1.28" pixels that scope gave me with my DSLR. I think it's a bit pricier today, but I'd still struggle to find a scope + corrector that beats it on a value perspective! A 1.25" corrector will probably be sub-optimal for a lot of beginner / budget minded people- a lot of them will use APS-C or 4/3 DSLRs or mirrorless cameras that they may already own or buy second hand off ebay.

From my own experience, I can say that a 130-PDS (about as cheap as they come) is very good for the price. Once you learn how to handle collimation yourself it's pretty rock solid and trouble-free. Mine paired with the Baader MPCC did let some out-of-frame reflections through but for 350 for scope and corrector you can't complain. I did find that it wasn't very suitable for a mono setup though, as the focuser is weak and the cost of upgrading it didn't make sense for the scope. All-in-all it is a strong recommend for someone on a tight budget! I will say though that for some reason, even the step up to an 8" newt is probably a bad move on a budget. For some reason even though it doesn't sound a lot on paper, that weight and size creates a huge amount of flex. My TS PHOTON 8" F4 was a nightmare that I eventually ran from light-speed. I guess that larger than 6" newts are best left to more expensive, higher-quality models... My 2p anyway. Adding this for any newbies reading the thread.

Tell me about it! I used about 1500 worth of kit until march this year. HEQ5 + pre-owned D3200 + 130PDS+BaaderMK3 CC. I used that from 2017-2022. Then in february I bought a risingcam 571. Then I bought £3000 woth of chroma filters... Then I replaced the 130PDS with an 8" f4 TS newt, which I never got to work as I liked... Then spent money on a second hand 130mm triplet... Oh no oh no. I looked up how much I spent in total this year... I felt very guilty... After 3 years of saving money and living with my dad to save for a "house deposit" i blew a lot of that in 9 months chasing better images haha. I'd been looking at even just the astrocam upgrade til then going "One day, but man they are expensive!"

Sadly you need to be careful when buying dedicated USB hubs too. I bought one from a local shop, USB3. And my RisingCam 571 complained about it only having a 2.0 connection, and did not work as a result. I ordered a Pegasus box on 31october... Still not here yet but flo said their expected delivery was in "early december". I guess Pegasus are struggling for volume.

A friend of mine found a website that did just this, for Linux tutorials. They were incomprehensible, wrong, repeated themselves. Totally useless, but they were able to get themselves onto the first page of google!

I wish not to be rude as I can only choose to assume the guy has best intentions, but the guy's website has a lot of clickbaity articles and based on the fact he is asking here for info, they probably aren't very useful. I did see one featuring a focusing mask made from chicken mesh (!?!). At least he seems to genuinely be doing the astrophotography and isn't just spamming articles wihout even touching a telescope, but in the end if someone wanted to know "what camera settings for astro" or "best camera for astro" or "best first telescope", they'd be better off if the website had links to relevant SGL and CN forum threads. I suppose researching threads, writing about conclusions from them and using the threads as references, academic style would work though? I know I gave up on articles for hobby advice years and years ago. Youtube can be good, forums are best, but articles are so much more likely to be clickbaity rubbish written by someone who barely knows the subject at best, or plain written by a computer (machine learning) at worst.

My present (collab between dad and grandparents) is already under the tree Stellalyra 6mm UWA by your recommendation! Looking forward to trying it out on mars if the weather cooperates before mars disappears again. Hope you guys have a nice Christmas period!