GT-81 Testing

[gbealnz]

Like Nadeem, I too have managed a few images.

The moon hasn't helped, but I wanted to test the new scope in various configurations. My gut feeling was that it would need some form of assistance with field flattening.

So I shot the scope native, with the TRF2008, and also with the Astrotech AT2FF, three separate shots.

The scope does need help, as the native looked a bit like Warp Factor Five. The TRF2008 worked wonderfully, as did the AT2FF.

This was of the Lagoon in Ha last night, using the H-16 and AT2FF, and again tonight with the M25C for about half an hour before the moon rose (it rose part way through the series).

Attached is a stack of 19 subs, each 60 seconds, GT-81, SXVR-M25C, AT2FF, captured and processed in Images Plus.

I'm happy, little or no chromatic that I can see. Nice scope.

Gary

[gbealnz]

Thought I might throw up the Lagoon Ha as well.

GT-81, SXVR-H16, Astronomik 12Nm Ha filter, AT2FF, 10 exposures 300 seconds.

Gary

[andrew63]

I think a few new owners will be breathing a little easier now!

[Whippy]

You mention that you can't see any CA with the scope, is this visually or with an OSC camera?

Tony..

[gbealnz]

Visually Tony, although I take your point, and promise I'll try an eyepiece soon. Having too much much fun imaging with it actually, loving it.

Gary

[Whippy]

I can imagine Gary, it looks like a cracking bargain if WO can keep up the QA that sometimes lets the budget APO's down. If they can manage it, this could quite easily take the place of the ED80 as the beginners APO of choice .

Tony..

[gbealnz]

Plan was a "Limited Edition", which hopefully adds a bit of mystique.

Forgetting all that, it's a nice usable scope. While my setup is a simple roll out/roll in pier, I could see this GT-81 appealing to someone having a portable setup or need.

Gary

[andrew63]

I was thinking from a purely grab and go set up Gary, this say compared to the megrez 90 - it certainly offers something different. Not sure of the advantages of using a triplet as a visual instrument though.

andrew

[ollypenrice]

Looking really great. Can you give it a try on a hot blue star? That's always been the key thing for me with apos.

Your Lagoon has gone really deep in the time.

Olly

[gbealnz]

Can do Olly, throw me a hint as to what star you want (something about the Souther Cross, or Scorpio might be nice). With OSC I presume as well?

Have been blasting away with the M25C and the TRF2008, aimed at B72, but may have been off. Having fun nevertheless. Moon has arrived so have switched to Ha with the H-16 and TRF2008. Have both M8 and M20 in the frame.

Fun it is.

Gary

[ollypenrice]

Oh heck, I don't know the southern sky at all! I just know that the difference I see between budget and premium apos is at its greatest with bright blue stars which bloat in some (only some) of the cheaper ones. It's the blue channel that suffers the most dispersion, naturally enough.

Olly

[gbealnz]

OK, will give it a shot. Be back to you, maybe tomorrow night. Heck, might even get rash and put an eyepiece in it, not sure why but to satisfy the urge perhaps.

Gary

[ollypenrice]

OK, will give it a shot. Be back to you, maybe tomorrow night. Heck, might even get rash and put an eyepiece in it, not sure why but to satisfy the urge perhaps.

Gary

Just occasionally I think to put an EP in the Tak 85 and the view is fabulous. It really is. Just a reminder, the EP goes in the thin end...

Olly

[gbealnz]

Well living in the "Land of the Long White Cloud" means cloudy skies and a fair chunk of poor weather, plus it IS winter after all, so the time available to trial this scope simply hasn't been there.

In answer to Olly's request I post here a compilation of four stars, no real science, and even less knowledge on my behalf, but I am sure the Englishman domiciled in France will pipe up and explain what it all means.

I shot as I finished up a few nights ago. Had the GT-81 on the mount, SXVR-M25c on the back, AT2FF in between.

In an absolute guess went to the Southern Cross. Shot all four Cross stars. Simple 10 second shots. Used Maxim, saved as FITs. Opened each in Images Plus, and de-bayered. Then opened DDP and hit "Auto" and "Apply". Saved the result as a JPEG.

The rest you will need to ask Olly.

Gary

[gbealnz]

Edit. Not all four Cross stars sorry.

From top left, clockwise, Acrux, Gacrux, Mimosa, Rigel Kentaurus. The cluster in the Mimosa shot is The Jewel Box. Rigel Kent is also known as Alpha Centauri, one of the Pointers.

Gary.

[ollypenrice]

No black magic on my part. The budget apos just throw up haloes, sometimes. Thanks to Gary's efforts above we seem to get the impression that this one doesn't. Good post, Gary, thanks.

Olly

[gbealnz]

My pleasure Olly, I am ever impressed by this little scope, and once it's slightly bigger relation arrives (maybe this week) it will get bolted on top, so an over-under combo. The M25C will spend a bit of time attached I suspect.

I'm hatching a plan to fit a spare F/T to it, not too much wrong with the stock DDG, but mine has a tad of image shift when I rack back and forth, plus the F/T is motorized, so auto-focus.

Gary