TS APO Triplet 90mm/f600 - experiences

[A McEwan]

Hi all,

Round about the beginning of Sept I got my newest telescope: the Telescope Service APO triplet 90mm/f600 (f6.67). I showed it off in the equipment gallery page but have kept pretty quiet about it since then. The reason being, I didn't want my comments to be coloured by New-Telescope-Tinted vision. That euphoric feeling that one's new toy (piece of scientific observation equipment) can't be anything less than perfection itself.

Well, some time has passed and I've had plenty of viewing opportunities, so here's the lowdown on my experiences so far. The good, bad and ugly.

The Good.

One of my first observations was of a Jovian transit. It was the best view of such an event I've had in any telescope. Admittedly I've only seen a few. The seeing contributed of course, but the shadow of the moon (Ganymede) was pin sharp and jet black. The disc detail was stunning that night and it honestly felt like I was looking through a telescope larger than 90mm - it seemed to feel like my old 100m ED in terms of detail.

There is no false colour. Either in focus, inside, or outside focus, there is none that I can detect. Also, the diffraction rings are perfectly round, smooth and concentric.

Star colour is vibrant and natural to my eyes.

Focuser is well-weighted and easily adjustable to perfection. It was very close to perfection out of the box. The fine-focus is very easy to use.

I was impressed by the Jovian performance, but I also wanted to assess it on DSOs too. Views of various DSOs have shown that generally, it performs like many other small aperture APOs. The Double Cluster, Ring nebula, Dumbbell nebula, Coathanger, M31 group, M33, M45, etc - all the usual suspects if you like, show the sort of view you'd expect from a good quality 80mm to 90mm ED scope. With one caveat - the field of view is flatter than I've noticed before.

Even with my 22mm LVW, an eyepiece that has a famously flat field, the view was even noticeably FLATTER than when I've used it in my previous small ED scopes. The view through my 13mm Nagler was even more noticeably flat, with only the very extreme edge suffering from any distortion at all.

This scope seems to have unchained the true optical excellence of my eyepiece collection. Not that my previous ED80 was a slouch - but the Triplet gives that little bit more performance from them. In terms of "feel" (very subjective I know) it's like using my old TV85 rather than my more recent SW ED80.

Viewing Comet 103P Hartley 2 over the last few nights has been a joy, especially with the Double Cluster so nearby.

I'm not that experienced with objective study of the limitations of scopes on double stars, but I have to say that the scope snaps to focus very well and has intense contrast, making double star viewing very pleasurable.

Unfortunately, I still haven't had a chance to observe the Moon with it, but am gagging to do so!

The Bad

I feel the extendable dewshield is a bit on the short side. This seemed to be proven by some marks appearing on the lens which had to be cleaned off after a series of days and nights of observing. I have since added an additional Astro-zap dewshield. Overkill? Maybe, but I think not.

The Baader Steeltrack focuser is held on by three round-tipped screws, which settle against a lip, holding the focuser body in place but allowing it to rotate. The rotation is locked by a large knurled thumbscrew. On one occasion, while my back was turned at a public event, somebody "did something to the focuser" which resulted in the focuser detatching from the OTA, along with my Baader Solar Wedge and Pentax zoom eyepiece! Disaster was only averted by a nearby sharp-eyed club member who CAUGHT the assembly before it hit the ground!!!

I have since made sure that the three screws that secure the focuser are all on the tight side, erring on the side of caution over rotation function. NB when I have rotated the focuser, it works perfectly with only very little repositioning of the target object within the field of view.

The scope is a bit heavy for a true grab'n'go definition, especially with a secure mounting plate for security. The OTA weight is stated as 3.5kg on the seller's website, but with a 2" diagonal and a sturdy plate (the William Optics Vixen Compatible Dovetail Plate) the weight is more like 5kg. My EQ3-2 takes it ok, but for high power viewing or photography I'd use my Vixen GP.

The Ugly

The case. There's a word for what the case is, but instead I'll just say it's not very good. The foam is soft and squishy and virtually impossible to cut - it flakes as soon as you take anything sharp near it. The precut hole for the scope is not cut to shape, just a rectangle that doesn't hold the scope firmly in position and actually makes it harder to get the scope out of the case without pulling the foam half out too. There is no padding on the inside of the top flap either, meaning that one or other of the focus knobs could be impacted if the case was knocked.

I find it hard to keep the carbon fibre tube clean, or to clean marks off it. Maybe there is a special product I should be using instead of breath-mist and microfibre cloth (only on outer tube, not objective!).

Conclusion

Fantastic optic. Lovely build quality. Excellent quality focuser. Heft and weightiness give a real quality feel. Colour-free, flat-field and a joy to use (apart from the case). Excels on planetary views.

Link to The scope for sale at Telescope Express

Thanks to Johninderby for his input in my decision to go with the 90mm triplet. His advice and experiences with his 80mm model were invaluable and much appreciated.

Ant

[Rossco72]

Nice review Ant, thanks for sharing your thoughts on this lovely sounding scope

[michael.h.f.wilkinson]

Thanks for the detailed review. The scope sounds really good. I think I will have to settle for the 80mm, however, otherwise the missus will start grumbling. And anyway, I can take that on a plane just a bit more easily.

[A McEwan]

Thanks guys. Generally, it is a stunner, and I'm sure the quality is the same in the 80mm model too.

[astroimpulse]

Going of pics alone it looks like every part is engineered to the highest of specs.

It's amazing looking. seems reasonably priced too.

And your review was very clear indeed.

I'd love to see more pics of refractors in hands or next to a common object to get a better sense of how big or small they are.

[ollypenrice]

Reveiws like this are so important in the astro community. Many thanks. I only wish I had a gap in the focal lengths that might justify one of these!!

Olly

[Astro_Baby]

Nice review - the scope looks very beautiful as well.

[A McEwan]

Thanks folks!

I did actually finally get a chance to use it for lunar last night, although of course it was Full Moon! Still, I could not detect fals colour on the limb, and Plato and the area around were nicely defined. I could not detect any craterlets within Plato, but with full illumination on the Moon I guess it's not the best time to look. Maybe in the next few nights I'll have better luck.

Ant

[Neil English]

Hi Antony,

Enjoyed the review. It's a great wee scope all right, judging by a few other 80mm triplets I've had the pleasure of looking through and that extra 10mm of aperture pulls in a bit more detail on Luna and planets. So, where does that put the WO Megrez 90 in the scheme of things?

Cheers,

Neil.

[A McEwan]

I've never looked through a Megrez Neil, so I can't answer from experience. I do know that anyone considering a 90mm scope has "Megrez" plastered on every website in front of them though, so it might be a hard to resist option. For me, I'm just glad I was steered in the direction I went in.

[Teal Rain]

Hi Ant

I've been thinking about down sizing the kit - again! - mainly as I really don't get a chance to use what I've got! The two options I see at the moment are the TV85 and the TS90.

I love the look and feel of TV scopes having had a Pronto but is the TV 85 really worth what amounts to about an additional £1K? - bit cheeky of me to ask:rolleyes: but in your review you did mention that the 90 compared to the 85.

Any advice welcome!

Cheers

Mark

[A McEwan]

Hi Mark,

So sorry for the late reply - you should've PM'd me! You've probably read the recent posts that compared the TV85 against a cheaper "standard" ED80 type scope. A TeleVue scope is a different beast mechanically and aesthetically and are often touted as "lifetime" scopes or heirloom instruments. Nothing wrong with that, but the TS90 with slightly more aperture (yes, I know... only 5mm....) and better colour correction is in technical terms "superior" to the TV85. It is not quite as heavy though and despite the fact that it is well made, does not "quite" have he solid feel of the TV scope.

Other than that, you won't regret buying either one.

Ant

[Teal Rain]

Hi Ant

Thanks for your reply. Should have PM'd you but it wasn't urgent!

Hmmhh some thinking to do!

Cheers

Mark