At the New Forest Observatory I have the most stunning refractor to review for Kieron at SCS Astro. I have not been very happy with the Takahashi Sky 90s, mainly the difficulty in collimating them, and then the not too good performance even when collimated. Specifically, even when collimated there is typically coma in the far corners of an APS size chip which is more than a bit annoying when the spec says that the imaging circle is a full 45mm with the reducer/flattner meaning it should actually fill a full-frame chip no problem. My dissatisfaction with the Sky 90s, and hence my lack of progress with the mini-WASP array project has been extremely frustrating and led me to look for alternatives to the Sky 90 to populate the mini-WASP array. Now having done my homework a couple of years back I was pretty much aware that there was nothing in the market refractor-wise that would help me out here. However, not expecting any joy whatsoever, I asked Kieron at SCS Astro whether there was anything new on the market that could possibly suit my application. Unbelievably a new scope from Sky-Watcher had appeared on the scene just a week earlier! This looked like a very exciting new product indeed and Kieron has very kindly shipped me the brand new Sky-Watcher Esprit-100ED quintuplet refractor to review – wowser 🙂
The real joy and appreciation of a job really well done started as soon as I had opened the cardboard box – seriously. Take a look at the first photo – there’s the Aluminium padded case holding its precious cargo – nothing new or novel in that – but now look closer. The Aluminium case is suspended from an outer metal framework by 8 powerful springs!! Oh yes – these guys know what they’re doing alright and they’ll be no cries of “it must have lost collimation in the shipping” with the care that Sky-Watcher have taking in packing their precious goods. Well done guys, there are a number of telescope manufacturers out there who could really take a leaf out of your book. I am highly impressed.
Be careful removing the refractor from its case – it is heavy. The bare OTA with no accessories at all weighed in at 6.3kg on the bathroom scales, but this is not “wasted” weight, this is precision-engineered sturdiness. That 11:1 focus controller is silky smooth and there is absolutely no slack or slop in the drawtube assembly which feels like it could support a tank. Looking down the business end of the scope is like looking into a black hole – absolutely no sign of reflection or light scatter from the inside of the OTA at all – even the flash used to take the photo got swallowed up in there. The baffling looks superb.
Well, those are my immediate thoughts on taking this amazing piece of glass out of its box and any further discussion of its performance will now have to wait until I have completed the optical tests. We have a 5-element objective here (hence the quintuplet) that is claimed to give zero detectable colour fringing. The scope itself is f#5 giving a focal length of 500mm with the 100mm aperture – absolutely perfect for my applications and my M26C one-shot colour 10-Megapixel CCD.
O.K. let’s not beat around the bush any longer, what have we got here? We have an FSQ-106 equivalent spec refractor (well 6mm off the aperture is neither here nor there) at less than half the price of the Japanese offering. If Sky-Watcher (Chinese) have got the optical design right (and I have absolutely no reason to doubt that they have) then they have a potential “Tak-killer” on their books – and jolly good luck to them. My main worry before trying the scope out for real is the possibility of lens flare from very bright stars due to all that glass – but I am pretty sure these guys have already thought of that and have that covered, but we’ll soon see anyway.
Keep watching the NFO site to see the next exciting installment on the Sky-Watcher Esprit-100ED quintuplet refractor review 🙂 🙂