Es Reid designs optical systems. He’s currently working on a very high powered and fancy microscope for an important company in Cambridge. On the side he bench tests commercial telescopes for First Light Optics and makes sure the telescopes they sell are up to scratch. As a result he is uniquely placed to give an unbiased assessment of the best telescopes on the market today. I had heard of him but was lucky enough to meet him at the Web Society Annual Meeting. A few weeks later I spent a whole 4 hours chatting with him about telescope design. I am extremely grateful for his generosity and the fact that he put up with me for so long. The interview breifly features in my latest video “5 telescopes that changed astronomy” and having been through the rushes I can only apologise for being such a demanding arse. Quite embarassing actually.
Sky-Watcher Evostar 72ED DS-Pro OTA
This is the best value ed glass small scope there is although full disclosure I’ve not yet used it. I have used some other small ed refractors and been disappointed with them. Es Reid says Sky-Watcher are now able to produce very good scopes at a very good price. In fact this one has been recommended to me by a number of nerd I trust. Its small so can be mounted on the AZ-GTi , and Star Adventurer GTi although I’d recommend the Sky-Watcher EQM-35
William Optics v2 RedCat 51 APO f/4.9
Es Ried is very impressed with this little scope. It’s VERY sharp. Its like a 250mm F4.9 lens but its sharper because instead of being made up of about 9 separate lens elements with an internal focusing mechanism its got just 4 with two of the elements being made out of exotic fluorite-like glass. Having so few lenses reduces problems of internal reflections and scattering and its Petzval design (which is used in the best widefield imaging refractors by Takahashi and Tele Vue) combined with exotic glass to remove colour fringing makes this one of the best widefield astrographs available. Its perfect when paired with a full frame DSLR camera and can be used with the dinky little Watcher Star Adventurer , AZ-GTi , and Star Adventurer GTi mounts. Plus you don’t need to buy a reducucer/corrector lens as the field is beautifully flat right out of the box.
Takahashi FS-60CB f/5.9 Doublet Fluorite APO Refractor OTA
The Tak FS60CB has a fluorite crystal front lens which reduces colour fringing making this scope ‘tak’ sharp. Es describes this scope as “delightful”. I’ve got one. If you combine it with the dedicated reducer you get a fast (F4.2) scope capable of resolutions of about 2 arc seconds which just happens to be the resolution of the Sky-Watcher AZ-GTi , and Star Adventurer GTi mounts (we measure mount wobble in arc seconds too). In essence this scope paired with these mounts (heads up the Star Adventurer GTi is much less of a pain to use than the AZ-GTi ) hits a portable astrophotography sweet spot (see this video about it). Everything is in balance. You do really need the reducer/flattener to get the most out of this scope which bumps up the overall price considerably. BTW if you don’t need to be ultra-ultra-portable the Sky-Watcher EQM-35 is an even better mount for a scope this size.
10″ f/8 M-LRS Ritchey-Chrétien Telescope OTA £2.5k
The Ritchey-Chrétien Telescope design is used by all the big observatory telecopes, including Keck and the Hubble Space Telescope. The reason is this design eliminates the big aberration which hampers most reflecting telescopes: coma. And of course being as the design is built on mirrors rather than lenses colour fringing is not a problem. So you’d think that these telescopes would be the goto telescope for all astrophotographers… but for years amateur RC scopes have been a real pain in the behind to collimate. This has lead to numerous complaints on the Astro forums and social media. According to Es Reid the latest GSO RC scopes have now solved these issues. They are mechanically good enough to do the job and therefore they fully realise the power of the RC telescope design. To get the most out of RC scopes you are well advised to make use of its coma free optics by shooting with a large sensor camera (preferably a camera with big pixels but small pixels are ok if the read noise is small). If you happen to be using an APC sized sensor of smaller you probably won’t need to invest in a reducer/corrector lens although if you are using a small pixeled camera then bringing down your focal ratio is a good idea). Also worth noting that the large central obstruction in this telescope design makes them not that good at planetary astrophotography. All in all a great value telescope for deep space astrophotography. For this 10 incher you will need to be using an EQ6-R PRO mount or similar to get the most out of this scope. Also note that GSO scopes are ‘rebadged’ according to who is selling them.
Sky-Watcher Esprit 120 ED PRO
According to Es Ried Sky-Watcher are consistently making high quality telescopes at a very good price. He’s particularly impressed with the Esprit range which he says are extremely sharp and pretty much bomb proof. Helena has one of these and her video suggests she likes it! You will to buy the dedicated reducer/flattener to get the most out of it. You’ll also need a pretty heavy duty mount. At 10kg this scope is too big for the EQM-35 mount so your looking at using a HEQ5 or the best mount which a reasonable mortal can afford the EQ6-R PRO
William Optics FLT 132
Es has tested many of these scopes and says they are “very good indeed”. He’s also noted that the quality of Williams Optic’s refractors have improved considerably over the last ten years. I have nothing else to add I’m afraid as I’ve never used one. You will need to be using an EQ6-R PRO mount or similar to get the most out of this scope.
Schmidt-Cassegrain telescope SC 279/2800 EdgeHD 1100 OTA
According to Es Ried the original SCT suffered from an aberration called spherical chromatism – especially in the blues. Apparently spherical chromatisim is what stitches up achromatic scopes more than the colour fringing and its what held back my skywatcher st80 in my robots vs nerds video! Anyways Es says the upgraded Edge HD SCT which was released in 2010 solves this problem by employing some lenses in front of the focuser which results in an “virtually apochromatic telescope over a full frame” which is “really very nice indeed”. One of the best members of Big Amateur Telescope Mr Crazy physicist has been lucky imaging with his C14 edge HD with spectacular results. You can also stick a hyperstar lens on the front for widefield imaging. It really is the best all round telescope on the market. I was so impressed I went and hired one (see oops… I’ve got a C14). I’ve got it until January but unfortunately my mount has been delayed so I haven’t been able to use it for anything other than planetary yet. Anyways the C14 is big. Too big to haul up onto the mount every night so I’m recommending the C11 which is much lighter and therefore easier to use and will work on an EQ6-R PRO mount.
Apochromatic refractor AP 150/1050 ESPRIT-150ED Professional OTA
This is the biggest APO refractor on the list. At nearly 5 grand the Esprit 150ED is expensive but still a third of the price of the Takahashi’s 150mm scope and according to Es Reid, the Esprit is just as good. According to Es this design is pretty bomb proof which means the esprit should be usable for decades. One thing to be aware of though is that big triplets take longer to cool down than doublets. For me that’s not a problem as it takes me so long to get all my imaging gear up and running! Last year a member of Big Amateur Telescope had one of these triplets and it was one of the sharpest scopes we had in the group. You will need to be using an EQ6-R PRO mount or similar to get the most out of this scope.