I think that 8 inch Newtonians hit a massive astrophotography sweet spot. Proof of this are seen in the astrophotos of the new generation of astrophotographers like Lyaphine.
Lyaphine who is member of my discord server (you can join us here) discovered a planetary nebula (right picture) with her 8 inch Newtonian while shooting NGC7159 (left picture)
More proof can be found in tests that were done in Big Amateur Telescope last year. I was keen to find the best gear for lucky imaging so we tested the sharpness of over 200 telescopes. We did this by simply by seeing how blurry in arcseconds the stars were in photos taken by our member’s telescopes. One test is not perfect because the results are affected by the seeing conditions but if you do lots of tests then when the seeing conditions are good the sharpest telescopes will rise to the top of the pile. As you’d expect at £10k the
Planewave CDK 12.5 and the C14 HD Eundge did pretty well, at £6k Orion Optics ODK12 was up there, so was the £5k the 6” Esprit apo refractor… so far all the usual suspects but then like a fish out of water at just £500 up popped a couple 8 inch Newtonians with mirrors made by Tiawanese company GSO . WOW! So I named these 8 inch F4 newtonians made by GSO the wow scope.
How to BUY the WOW Scope!
Buying these 8 inch newtonians is a little bit confusing because they are rebadged by whoever is selling them. For instance in the UK FLO call them Stellalyra , in the Europe they are know as TS Photons , in the USA OPT calls them TPO and High Point Scientific calls them Apertura . They are all made by the Tiawanewse company Guan Sheng Optical. I supsect GSO’s mirrors are better than those sourced by other Chinese companies like Sky-Watcher.
These fast newtonians need a very good coma corrector to get the most out of them like Tele Vue’s Paracorr
My affiliate links
I think that the main reason these scopes perform so well is that their native resolution is about 1 arcsecond. And that is very similar to the maximum resolution that can be achieved by any telescope on earth due to our wobbly atmosphere. In the UK sometimes the atmosphere is so wobbly you can’t resolve things smaller than 3 arcseconds and when the seeing is good 1 arc second is about the best you can hope for. So in a sense these wow scopes aren’t amazing they just happen to perform as well as much more expensive scopes because the seeing puts a limit on how amazing these expensive telescopes can be. Another way of looking at it is that people who buy more expensive scopes are a bit stupid for wasting their money on something that will never be able to perform as well as it could. Why buy a Ferrari when the speed limit on the motorway is 70mph etc… Perhaps that’s a bit harsh because actually these more expensive scopes do have their place especially if you have a large sensor but I hope you get what I mean.
So the 8 inch F4 Newtonian just happens to be the most cost effective telescope that hits the resolution ceiling set by our wobbly atmosphere. Oh and its fast which means you can go deep which is the reason why Lyaphine managed to discover her own planetary nebula. But heads up these Newtonians aren’t perfect.
PROs
- Resolution similar to that of the wobbly atmosphere: no point in going bigger
- Price: Mirrors are much cheaper than refractors at this resolution
- No Chromatic aberration
- Still small enough to fit on a relatively small mount: Even managed to fit one on an EQM-35 (see here) but really an HEQ5 or EQ6-R PRO is needed.
- Fast Focal Ratio
- Works with small pixel cameras
CONs
- Coma; needs good coma corrector and the best cost around £500
- Need to know how to Collimate: My Patrons have access to a collimation tutorial video and I answer their questions in hidden channels on my discord server.
- As with all newtonian telescopes dew forming on the secondary mirror is a problem.
The biggest problem with a fast Newtonian telescope like the wow scope is coma. So you need a really good coma corrector. The best coma corrector I know of is tele-vue’s paracorr.
But this coma corrector pushes the focus position of your camera 4 cm further away from the tube. If you have a heavy camera that’ll put a lot of strain on the focuser and you will probably need to upgrade the wow scope’s focuser.
Another issue is dew forming on the secondary mirror. I am currently trying out a modified secondary mirror dew heater made by scopetech which I’m modifying to reduce the width of the wires… I’ll let you know how I get on.
Heads up Lyaphine’s telescope is an upgraded version of the wow scope called a 8″ f/4.5 ONTC Carbon Tube Newtonian telescope – fully customizable by telescope services. It has a carbon fiber tube, a better focuser and you can move the primary mirror up and down the tube which helps if you use a tele vue coma corrector. These extras make her scope £1k more expensive than the wow scope.
Long time watcher, love your content.
Came here from your “best telescope” video. Just want to let you know that the link to the EQ6-R Pro (PROs section) is broken.
That’s all, keep beeing entertaining!
thx mate much appreciated,
actually mate they seem to be working for me. If you haev the time to tell me which link wasn’t working I’d appreciate it👍
I think he means the one on this page.
In the Pro’s and Con’s the EQ6-R link goes to a “page not found”.
ahh thx mate, (and doh!)
Astrobiscuit, on crumbs found for this link: https://amzn.to/3gHHOwv
I thinks its this ? https://www.firstlightoptics.com/tele-vue-telescopes/tv_paracorr_2.html
yes but if you use my link then I earn a small commission which will make me very happy and won’t cost you any extra😁thx
https://www.firstlightoptics.com/tele-vue-telescopes/tv_paracorr_2/ref/astrobiscuit
Deleting my comment makes me unhappy! It is rude and diminishes traction with search engines.
I will not be buying anything through your links as a result.
Was it worth it just because you thought you were cleaning up the page to delete my comment ?
I am sorry that it makes you feel unhappy; please do not take it personally, this is how site moderation works. Astrobiscuit is doing all this works because he really loves it, and the easiest (and free) way to pay him is to use the links he provides. I find these tutorials and videotutorials extremely useful and I hope one day to have the funds to become a patreon.
I honestly don’t know what comment I deleted. Or at least I can’t remember deleting it. Are you sure your comment posted? If it makes you happy please repost. Obviously being as I’m skint and struggle to put out videos I would much prefer it if folks used my affiliate links.
Thanks AstroBiscuit for all the hard work you put in, don’t listen the negative people ! 😁
thx mate
Hi Astrobiscuit
I see you’re featuring my scope !! 🙂
I was always very pleased with the images I could produce using a QHY8 camera – certainly not the lightest of cameras !
Clear Skies
Don
For us Australian viewers who may be keen to grab a well priced 200mm f4 Newt Astrograph, keep an eye out for Bintels version.
https://www.bintel.com.au/product/bintel-bt200-f4-imaging-ota/
So glad I read this as I’ve been debating buying a 200mm with a HEQ5 for my 1st astrophotography rig – I’m a firm believer on spending a couple of quid on a decent setup at the start of any hobby or interest to give yourself a fair ‘crack o’ the whip’
Makes me feel I made the right decision as you know loads more than me
I really look forward to the youtube videos Mr. AstroBiscuit.
I wonder where the name came from? is there a Biscuit Nebula??
Now to get serious, there are many great telescopes out there but the best one will vary from person to person. I really like that you have recommended 8-inch reflector and can certainly agree that reflectors are great for astrophotography, having a mere 5-inch one.
The telescope brand is also important according to my research here:
https://astroimagery.com/equipment/telescopes/discover-the-best-telescope-brands-for-amateur-astronomers/
You know that all the brands simply relabel stuff that comes out of the same factories in china? GSO based telescopes are the exception their factory is in Taiwan and I recommend the GSO newtonians which are relabeled with names like TPO and Stellalyra, Apertura…
The high end stuff isn’t made in China but most of the rest is.