Tecnosky 90mm Triplet F6 APO

[megrez]

Hi all,

This is a first post, so apologies if things don't quite work out.

About a month ago I purchased a Tecnosky 90 OWL Triplet APO from Astrograph.net. I have had a number of nights under the stars with it now and thought I’d try to do a short review on it.

A year ago I started imaging again after a long hiatus. Initially I had an Astro-Tech AT102ED, bought many years ago for visual use only. I purchased a new mount, an Ioptron GEM45 and started imaging with my Fuji XT2. Half a year ago the XT2 was replaced with a ZWO533MC which improved my imaging quite a bit. But the AT102ED, whilst great visually, showed too much blue bloat. After a lot of messing around with filters and processing time with Pixinsight I decided I to get a ‘proper’ apo.

I started to hunt around for ‘medium-sized’ scopes, that should not be much larger and heavier than the 102 – for now my setup is mobile and a shoulder injury means I have to be very careful with lifting equipment. There seemed to be a shortage of medium-sized apos during the summer. The one supplier in the UK who stocked a 102/f7 apo refused to answer emails with questions despite repeated attempts. Then Astrograph offered a gorgeous looking Tecnosky 90OWL on their website and I was sold (I’ll do a separate review of the excellent service by Astrograph separately).

Tecnosky 90  Triplet f6 'OWL' APO

The Tecnosky 90 OWL is a triplet with Ohara FPL-55 glass and a guaranteed minimum strehl of 0.95. It goes through numerous inspections, at the factory, at Tecnosky and Rupert at Astrograph also checks it out before dispatch. And comes with a test report. In my case the strehl was 0.98 (well, 0.975, but hey…). It has a high quality 2.5” rack and pinion focuser which moves just as smooth as the Feathertouch on the AT102ED and feels just more heavy-duty. You can rotate the whole focuser and there is an additional rotator at the end of the drawtube, which is a great help when trying to frame an image. The sturdy telescope rings sit on an oversized Vixen style dovetail and a very convenient carrying handle is mounted on top of the rings. The rings feature 3 M6 bolt holes on each side, that will be very useful with mounting extra gear or what have you. The metal lens cap features a picture of an angry or fed-up looking owl.

The telescope has a very solid feel and at 5kg is just an itch heavier than the old AT012ED. And it looks gorgeous in my eyes (did I say that already?).

The telescope arrived well protected in a very sturdy flight case within a thick carboard box.

So far so good. But how does it behave under the stars? Well, perfectly really! I purchased this scope for imaging purposes, but couldn’t resist getting out my old eyepieces and have a peek. Perfect airy discs and no sign of colour that shouldn’t have been there. Beautiful views of Jupiter, the moon, and amazing tack-sharp wide star fields. So that’s what they mean with apo-quality! I really must invest in better eyepieces now to get the best out of this visual feast. The last time I enjoyed looking through a telescope as much as this was when I still had my Intes Micro MN56, well over 10 years ago.

And for imaging, just what I was wanting from it, no more blue bloat and the stars are noticeably tighter. Within the small field of view of the ZWO533MC there was just a hint of field curvature in the corners, to be expected from an f6 triplet. A Hotech SCA field flattener took care of that. I kitted it out with a ZWO EAF. That was a doddle, the focuser has spare holes located just right, as if it is made for it!

Both Tecnosky and Astrograph mention a focal length of 560mm, making it f6.2. But plate-solving shows the focal length to be 540mm, confirming the f6 that is printed on the lens cell.

In all, I am very happy with this new scope.

Below are a couple of pictures of the setup as well as an image taken with the scope and ZWO533MC of NGC6946 and surroundings (60 x 180s, with ZWO IR/UV cut filter). I know there’s a lot of room for improvement in the last one. I’m still getting to grips with Pixinsight et al, but it’s the best I have managed so far and I’m well chuffed with it.

[callisto]

Nice review, thanks for sharing 

 

Mark.

[Highburymark]

Very nice! Thanks for the report. I bought a little Tecnosky 60ED and have been impressed with the build quality. Yet to get it under the stars, but they seem to offer excellent value

[Stu]

Nice review of a lovely looking scope. 90mm f6 is a very handy size, and would make an excellent travel scope for visual, as well as for imaging. The quality on these scopes (Technosky and the various clones) looks to be excellent and as you say, the focusers are right up there too. Have fun with it! 👍

[johninderby]

Tecnosky scopes seem to be popping up quite often now on SGL 🙂

Nice review of what seems like a seriously good scope. 👍🏻👍🏻👍🏻

[drjolo]

Mine just arrived - serial number 7, and Strehl 0.973.  It looks gorgeous, quite heavy, focuser works smooth and is quite stiff. Collimation checked with Cheshire is perfect.

But the weather forecast is not promising at all, unfortunately