Jump to content


Photo

Overdue First Light: Astrotelescopes 152 f/5.9

  • Please log in to reply
191 replies to this topic

#1 jrbarnett

jrbarnett

    Eyepiece Hooligan

  • *****
  • Posts: 20039
  • Joined: 28 Feb 2006
  • Loc: Petaluma, CA

Posted 14 October 2012 - 11:25 AM

A colorful scope deserves a colorful first light report, so here goes.

Color. Of the inauthentic variety. Oodles and oodles, even at very, *VERY* low magnifications. In the 30mm Astro-Tech Titan II and 27m Panoptic during alignment of the mount, the first and second magnitude alignment stars showed pronounced blue-violet haloing. It was unmistakable.

Whew. Now that the color question is out there, I feel much better. Don't you? So, putting aside the fact that this scope has precisely the plentiful amount of false color that you should expect a 6" f/5.9 crown & flint doublet to have, how was it?

Not bad at all, actually. The scope produced lovely highly contextual views of late summer/early fall classics. Even with moderate magnification 64x; 1.3 degree FOV with a 14mm Series 4000 UWA). The eastern, then western Veil segments were nice with a 2" O-III in the 27mm Panoptic and 30mm Titan II ED were nice. Bright, large globulars like M13 and M22 were neat; reasonably resolved around the edges, and peppered through their cores, even at low magnification, with a lot of spangled sky surrounding.

The Double Cluster was nicely framed as were the Pleiades, though I felt that the Double Cluster wasn't showing as many stars as it should (i.e., looked surprisingly under-resolved for the aperture.

On the optical quality front, the optic is surprisingly good for such a large, cheap doublet. Intra-and-extra-focal diffraction patterns were similar but not quite identical, but nothing to raise eyebrows.

Being a glutton for punishment, I ran the scope up to 224x to see how it handled higher magnifications. I'd be remiss not to mention the false color again in this context. Rasalgethi was fiery orange brand (surrounded by a HUGE violet halo) with a tiny cerulean follower, surrounded by a modest violet halo, in tow. I'd be lying if I didn't say the color was distracting. On the other hand, it was a nice wide split.

*bugle call*

Calvary to the rescue! Just when we thought our gooses were cooked in a briny stew of purplescence, the US Calvary comes charging over the hill, Old Glory flowing overhead, and the purple bandits scatter (somewhat) on the winds. Okay, not the calvary, but instead my vintage Sirius Optics MV-20 minus violet filter. It really did save the day on double stars at high magnification with this scope. Rasalgethi, for example, was cleaned up nicely to the point where the errant color was reduced by ~80% (SOTP) and the split was very aesthetic, with the primary and secondary showing their true colors much better. I would not bother to use this scope at >100x without some kind of violet blocker in place, at least on bright targets.

So, where do I think this scope comes out on the value front? That's a toughie. The price isn't huge...for a well-built, large refractor. The price is huge, however, relative to some alternatives to be discussed in a moment. The scope is massive. Longish, heavy and not well-balanced (it's needlessly front heavy; it's not a triplet). The dew shade could be reduced in weight by going with a thinner gauge's material, and that would help a bit. The Stellarvue version of the new Chinese R&P focuser (also sold on APM scopes and a few others, now) was good, though extended use of it and the Long Perng Crayford, same night, I have to give the nod to the Long Perng as being a bit smoother, and lower in shift than the Stellarvue.

Were you to come to me and say "Jim, I'd like the best deal money can buy in a 6" OTA, and I want to spend $1000 or less" I would not recommend this scope. Instead I'd steer you quickly to the $400 Celestron C6 OTA. Sure, you get a big CO and give up "rich field" observing, but in every other respect I think the C6 handily surpasses the Astrotelescopes big achro. Here's a dirty little secret - the C6's images are actually a little brighter and on clusters and at like magnification (~88x in each) it goes a little deeper to boot. The Ceelstron f/6.3 FF/FR even gets you back some of the contextual feel of the big achro, too.

So, I'd say overall the scope is neat for the right buyer - someone looking for a modern day equivalent to a Jaegers 6" RFT achro or similar. But other than that niche group, I think most buyers would be better served with something else. :shrug:

Regards,

Jim

#2 junomike

junomike

    Surveyor 1

  • *****
  • Posts: 1827
  • Joined: 07 Sep 2009
  • Loc: Ontario

Posted 14 October 2012 - 12:07 PM

Jim, That's one of the most truthful, unbiased reviews I've ever read!
I wish more people could see through the NCF (New Scope Filter) which sometimes hides or blocks out the true facts.

Seriously, this review needs to be placed under the "Reviews" section of CN so others can easily find It.

Good Job!

Mike

#3 stevew

stevew

    Now I've done it

  • -----
  • Posts: 4295
  • Joined: 03 Mar 2006
  • Loc: British Columbia Canada

Posted 14 October 2012 - 01:09 PM

Here's a dirty little secret - the C6's images are actually a little brighter and on clusters and at like magnification (~88x in each) it goes a little deeper to boot.

Regards,

Jim

Very curious..... :question:

#4 johnC

johnC

    Explorer 1

  • ***--
  • Posts: 75
  • Joined: 24 Aug 2006
  • Loc: Hucknall Nottingham UK

Posted 14 October 2012 - 01:29 PM

Certainly not the findings of the ones sold here??

#5 dakota

dakota

    Mariner 2

  • *****
  • Posts: 235
  • Joined: 11 Dec 2011
  • Loc: SD (God's Country)

Posted 14 October 2012 - 01:52 PM

I certainly disagree with his evaluation. Of course keep in mind that I have never looked thru a Tec, TAK, or AP. Nothing against Jim but I find the scope worth every penny.

Of course I am the type of person that doesn't spend all of my time evaluating things, I would rather be out enjoying what I have and using it for it's intended purposes.

#6 stevew

stevew

    Now I've done it

  • -----
  • Posts: 4295
  • Joined: 03 Mar 2006
  • Loc: British Columbia Canada

Posted 14 October 2012 - 02:16 PM

As a past owner of a Jaegers 6 inch F-5, and a current owner of an Antares 152 F-6.5, I can certainly attest to the wonderful views that a large RFT refactor can provide.
Yes, these scopes are specialized instruments designed for rich field viewing under dark skies. As long as the prospective buyer understands that he is not purchasing a planetary telescope I would think that the Astrotelescopes 152 would be a good buy. Never the less it seems that at some point we all still aim these rich field instruments towards the planets.
I think it's just human nature. Like wanting your F-10 SCT to be a rich field instrument.
Most of the time it's disappointing. In my own 6 inch RFT the spherical aberration starts to creep in around 100X.
Still when they are used for what they are designed to do, they can be wonderful instruments.
Good report Jim, as usual.

Steve

#7 jrbarnett

jrbarnett

    Eyepiece Hooligan

  • *****
  • Posts: 20039
  • Joined: 28 Feb 2006
  • Loc: Petaluma, CA

Posted 14 October 2012 - 02:27 PM

Dunno, Steve. Perhaps the large swath of defocused portions of the visual spectrum affect the "tightness" of the in-focus stars. Perhaps the optics are a bit rough. Perhaps there's some attenuation happening. Perhaps the baffling isn't as effective as it should be. Lots of possibilities. It's not a bad scope. It's actually a very entertaining scope, but there are several liabilities that come with it that I suspect would irritate many users.

From my perspective there were no surprises. I expected false color, and received it, expected mass and length, and received them, and expected decent optical and mechanical quality, and received them. On the value front, though, unless someone is Hellbent on having a 6" fast achromat, there are other 5 to 8 inchers that would likely be easier to live with and more well-rounded, for the same or less money.

Regards,

Jim

#8 dakota

dakota

    Mariner 2

  • *****
  • Posts: 235
  • Joined: 11 Dec 2011
  • Loc: SD (God's Country)

Posted 14 October 2012 - 03:08 PM

So what do you say to the reviews by Warren Maguire on the CT152 and Larry Carlino on the AT152? Are you saying they are wrong? As usual with your review and the other 2 reviews they are merely self opinions which don't necessarily reflect the views of others.

Yes the dew shield is heavy, but a few strips of felt took care of it sliding at zenith. I would rather have a heavy duty dew shield than some piece of plastic. With regard to your views on the focuser, they are your views and not mine. I have 2 of the 2.5 Stellarvue focusers and in reality I find the one on the AT152 somewhat better than the one on my SV110.

Maybe you just received a 'bad' unit of the AT152. Perhaps you should return it for exchange or your money back.

#9 mgwhittle

mgwhittle

    Apollo

  • *****
  • Posts: 1365
  • Joined: 24 Aug 2011
  • Loc: Chattanooga, TN

Posted 14 October 2012 - 03:17 PM

Thanks for this review, Jim. I came very close to buying one, even started a thread about it. I began to suspect that there was more color than owners were talking about, the "new scope filter" as Mike mentioned, and therefore decided to pass. After reading this review, I'm glad I didn't buy one. I agree that the AT152 plays to a specific audience, many which are happy.

#10 t.r.

t.r.

    Skylab

  • *****
  • Posts: 4422
  • Joined: 14 Feb 2008
  • Loc: 1123,6536,5321

Posted 14 October 2012 - 03:33 PM

Jim, don't tell me you didn't look at Jupiter or the moon with this scope?!?

#11 jrbarnett

jrbarnett

    Eyepiece Hooligan

  • *****
  • Posts: 20039
  • Joined: 28 Feb 2006
  • Loc: Petaluma, CA

Posted 14 October 2012 - 04:24 PM

"Are you saying they are wrong?"

Yes, actually. There was no mistaking the chromatic aberration. It has loads and loads. Of course, it's nothing that a cataract or two couldn't mask. :grin:

Given my experience with scopes, I can assure you that there's nothing "wrong with mine". I did star test it. I used it at high magnification, with and without filters. It performs exactly as a 6" f/5.9 achromatic doublet ought to perform. Given that I received exactly what I expected, and the scope is in perfect working order, in conformance with the laws of physics even, why would I return it for a refund?

With respect to the dew shade, there's a big difference between good design and plastic. I didn't say plastic. Take a look at any high end refractor. The dew shade material is thinner walled than the OTA material, and typically of the same material. That's the way this one should have been done, too, to avoid needless balance issues. Look at the image below showing how far back in the rings the OTA sits. Compare that to pictures of other OTAs on their mounts.

On the other hand, I typically don't take deficiencies my gear suffers personally. :winky:

Regards,

Jim

#12 jrbarnett

jrbarnett

    Eyepiece Hooligan

  • *****
  • Posts: 20039
  • Joined: 28 Feb 2006
  • Loc: Petaluma, CA

Posted 14 October 2012 - 04:27 PM

Now, mit picturen!

Posted Image

Posted Image

Posted Image

Regards,

Jim

#13 jrbarnett

jrbarnett

    Eyepiece Hooligan

  • *****
  • Posts: 20039
  • Joined: 28 Feb 2006
  • Loc: Petaluma, CA

Posted 14 October 2012 - 04:34 PM

And I have to post these...

Planewave 12.5" Corrected D-K on AP-900.

:bow:

Posted Image

Posted Image

- Jim

#14 astrogeezer41

astrogeezer41

    Vostok 1

  • *****
  • Posts: 102
  • Joined: 27 Aug 2010

Posted 14 October 2012 - 04:41 PM

Thanks for the informative review, Jim. I had been looking forward to it. It seems to me that you are just telling it as it is. - Robert

#15 jrbarnett

jrbarnett

    Eyepiece Hooligan

  • *****
  • Posts: 20039
  • Joined: 28 Feb 2006
  • Loc: Petaluma, CA

Posted 14 October 2012 - 04:42 PM

Nope. By the time Jupiter was up above the eastern treeline, I'd already bagged the AT152 in favor of a different OTA for the remainder of the session. Honestly, based on what I and the other two observers experienced on Vega and even Magnitude 2.9, ruddy, Rasalgethi, I'd pretty much decided that I would be sticking to DSOs with this puppy. It's going to be my Giant Monocular.

I think I'll order a 40mm ES 68, and JB weld it into a diagonal, and then the diagonal into the focuser. That way, no one else accidentally hurts themselves on a bright target. :lol:

- Jim

#16 johnnyha

johnnyha

    Fly Me to the Moon

  • *****
  • Posts: 6500
  • Joined: 12 Nov 2006
  • Loc: Sherman Oaks, CA

Posted 14 October 2012 - 04:48 PM

Thanks for the report Jim. I was also thinking some of the differences with the C6 at equal magnification could be explained by f5.9 v. f8.

#17 jrbarnett

jrbarnett

    Eyepiece Hooligan

  • *****
  • Posts: 20039
  • Joined: 28 Feb 2006
  • Loc: Petaluma, CA

Posted 14 October 2012 - 04:52 PM

f/10 actually, but f/6.3 with the FF/FR in the optical train.

Regards,

Jim

#18 johnnyha

johnnyha

    Fly Me to the Moon

  • *****
  • Posts: 6500
  • Joined: 12 Nov 2006
  • Loc: Sherman Oaks, CA

Posted 14 October 2012 - 04:56 PM

Oh, I though you were talking about the refractor! :foreheadslap:

#19 Mike4242

Mike4242

    Apollo

  • -----
  • Posts: 1085
  • Joined: 02 Nov 2011
  • Loc: West Tennessee

Posted 14 October 2012 - 04:56 PM

I think this is a fair review based on what I've seen with my AR152. The AT-152 definitely balances farther back in the saddle than the AR152 -- that must be one heavy dew shield.

Yes, actually. There was no mistaking the chromatic aberration. It has loads and loads. Of course, it's nothing that a cataract or two couldn't mask.


I've noticed the same in the AR152. I even noticed CA on 3.5 magnitude Sheliak, B Lyr. The AT-152 supposedly has better color correction than the AR152 though.

I think as long as the buyer knows what they're getting with one of these fast achromats, there shouldn't be too much disappointment. However, I could see where an unwary buyer could plunge into one these 6" achromats, lured by the attractive price and aperture, only to be sorely disappointed.

I'm personally not bothered too much by the amount of CA in these scopes, I tend to become so immersed in the object of study that I don't even notice the CA. However, the CA tolerance varies from person to person and for someone obsessive about their gear, it is probably very difficult to look past.

#20 stevew

stevew

    Now I've done it

  • -----
  • Posts: 4295
  • Joined: 03 Mar 2006
  • Loc: British Columbia Canada

Posted 14 October 2012 - 05:05 PM

I think the Astrotelescope 152 is a funky looking scope.
Spending an evening with a "giant monocular" can be a wonderful evening in my books.
I think of my Antares 152 the same way.

Steve

Attached Files



#21 jrbarnett

jrbarnett

    Eyepiece Hooligan

  • *****
  • Posts: 20039
  • Joined: 28 Feb 2006
  • Loc: Petaluma, CA

Posted 14 October 2012 - 05:15 PM

"I'm personally not bothered too much by the amount of CA in these scopes,..."

Ditto, Mike.

Where things get hairy, though is when someone goes and buys one on the basis of "very little false color" claims, and finds otherwise after the fact of purchase.

I'll put it this way. It's highly unlikely that someone buying a scope, expecting it to have lots of false color, but who instead finds it to have less than expected, will feel cheated. On the other hand, there are probably quite a few who, if they bought a scope with the expectation of minimal false color, but found instead that it has quite a lot, would feel somewhat misled.

One last point, while individuals' ability to recognize false color may indeed be different, I don't think the presence or absence of false color falls in the realm of "opinion". Optics can be analyzed and the degree of defocus of unfocused wavelengths relative to in-focus wavelengths can be measured. The larger the amount of defocus (in distance terms) of any visual wavelength, the more chromatic aberration the optic factually has, whether or not a given user recognizes it.

The Great Lick (36" Clark achromat in San Jose, CA) has certain visual wavlengths several *INCHES* out of focus when the image appears to be focused. Obviously this little scope wasn't that bad, but I have no doubt that if Vlad had the prescription for the optic, he could tell us exactly which wavelengths were defocused and by how much when the image is in-focus.

Regards,

Jim

#22 jrbarnett

jrbarnett

    Eyepiece Hooligan

  • *****
  • Posts: 20039
  • Joined: 28 Feb 2006
  • Loc: Petaluma, CA

Posted 14 October 2012 - 05:19 PM

Yep.

I'm toying with the idea of running the 2013 Messier Marathon with mine. Talk about "fish in a barrel". With a 40mm 68 degree eyepiece, I'd have 3 degrees of TFOV and 6-inches of light gathering and resolution.

The 6" f/5.9 is dead! Long live the 6" f/5.9! :lol:

- Jim

#23 dakota

dakota

    Mariner 2

  • *****
  • Posts: 235
  • Joined: 11 Dec 2011
  • Loc: SD (God's Country)

Posted 14 October 2012 - 09:13 PM

I don't recall accusing you of saying the dew shield was plastic. I don't recall the other reviewers saying the was no CA. Seems like you are the one twisting the facts mister. :whistle:

Reread your initial review. Came out pretty strong with negatives. I didn't take anything personally. So no need to throw that barb into the discussion.

I have no problem with the balance. My lowly CG-5 handles this scope quite well. Just balance it properly and one is all set.

Again, this is your opinion which you are entitled to. So don't take it personally when someone doesn't agree with you.

#24 MikeBOKC

MikeBOKC

    Skylab

  • *****
  • Posts: 4450
  • Joined: 10 May 2010
  • Loc: Oklahoma City, OK

Posted 14 October 2012 - 09:29 PM

I will say this -- those husky 6 inch achros LOOK like a telescope ought to!

#25 jrbarnett

jrbarnett

    Eyepiece Hooligan

  • *****
  • Posts: 20039
  • Joined: 28 Feb 2006
  • Loc: Petaluma, CA

Posted 14 October 2012 - 10:32 PM

Yep. They are stout little blighters. Like a doublet "blintz".

You can't see it too well from the lens on image, but the cell sits far forward inside the extended dew shade. Only about half the length of the dew shade actually extends past the front element as a result. Dare I say it, but - *sigh* - another questionable design decision on the shade. But for some odd reason these fast 6" achromats have always suffered from "too short dew shade" syndrome. Only the second iteration of the Antares 6" f/6.5 unit fixed the historic dew shade issue.

Here's another "bidness end" shot:

Posted Image

Regards,

Jim






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics