Saturday, 3 March 2018 | Colin
I purchased the Skywatcher ED72 primarily as a travel scope and a replacement for a much loved but damaged Williams Optics Megrez 72, which is now no longer manufactured. The WO was a great performer and its short focal length of 432mm gave sharp, wide field views with almost no sign of colour fringing, especially at low magnifications. The ED72’s identical aperture and 428mm focal length make direct comparison with the Megrez a reasonable proposition.
Both scopes feature doublet ED Apo optical design and neither Williams Optics nor Skywatcher disclose the specification of the ED glass element, other than to state that they are not FPL 53 glass. The “Schott” glass logo of the second element, however, features prominently on the ED 72’s tube. It was the great optics, build quality and portability of the Megrez that attracted me a few years ago, so would the ED72 make a worthy replacement?
FLO gave their usual prompt delivery service and the well packed scope & Vixen Porta mount arrived within three days of ordering. The ED72 is certainly a handsome looking instrument and comes with a good quality aluminium carry case with plenty of room for essential accessories. The OTA is noticably lighter than than the Megrez (1.955Kg v’s 2.2Kg) hinting at thinner tube construction and mirror cell, but as I’m using it on a Vixen Mini Porta alt-az mount, that’s no bad thing. The operation of the Megrez 72 was a joy, with a silky smooth 2” crayford focuser and 1:10 gearing. It was perhaps optimistic to expect this kind of refinement for the amazingly low price of the ED72 and indeed the mechanical operation of the ED72 is not as smooth. That said, there’s nothing wrong with focuser and resistance adjustment is possible via a couple of Allen key bolts. The robust tube rings, snappy metallic green coated Vixen style dovetail and screw threaded aluminium lens cap all add to the impression of a well designed and manufactured instrument.
Both scopes feature doublet ED Apo optical design and neither Williams Optics nor Skywatcher disclose the specification of the ED glass element, other than to sate that they are not FPL 53 glass. The “Schott” glass logo of the second element, however, features prominently on the ED 72’s tube. It was the great optics, build quality and portability of the Megrez that attracted me a few years ago, so would the ED72 make a worthy replacement?
First light for the scope was under a waxing gibbous moon from a fairly light polluted garden, using the optional Skywatcher 2” 28mm LER eyepiece and a Celestron 2” XLT diagonal. The eyepiece is a bit of a bargain being of great quality for the price and the image of the moon was very pleasing, with no colour fringing evident. Craters really stood out, with well defined shadows and bright peaks. Details on the terminator were impressive and contrasty. M45 presented pin point stars, with comma only visible towards the edges of the FOV. To push things to the limit, I dropped in a 1 1/4” reducer to the diagonal and a 4x image-mate barlow with 20mm Plossl eyepiece (x84 magnification) to try some double star work. Indeed, Alpha Geminorum was very cleanly split into its A and B components with clear diffraction rings around each. The initial impression I was left with was that the views through the ED72 are indeed very similar to the old Megrez 72. OK, so it may lack some of the engineering refinement of the Megrez, but for its £265 prices tag, it is very impressive indeed. I may well try imaging with it over the next few months.