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Overdue First Light: Astrotelescopes 152 f/5.9

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#51 drollere

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Posted 16 October 2012 - 12:51 AM

"it also begs the question why one wouldn't use an 8" or 10" ƒ/4 newt for RFT pleasure"
...
That's an easy one, Bruce. The eyepiece would be at the wrong end of the OTA.


jim, you need a shorter mount ... or taller shoes.

#52 doctordub

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Posted 16 October 2012 - 10:30 AM

Jim, Your star test sounds like you have some SA that I have not seen on mine. I mentioned in another thread you could clearly see the CA as a tight line on the Lunar limb and crater shadows in my photo without chromacor. I find that niether a 6" SCT nor an 8" SCT were a match for my AT 152. I hope the quality controll has not changed since the 1.5 years since I purchased mine.

Luna without chromacor.


Were you just comparing views of planets and the moon with your AT 152 against 6" and 8" SCT's? Or was that for several deep sky targets as well.

Bill


Bill, the 8" SCT is a little brighter on DSO, but the view in the AT 152 was more pleasing. This is after the Cat is properly cooled. My scope has almost no SA which is why I waited for a Null corrected Chromacor, but the with the CC in place it snaps to focus.

CS
Jonathan

#53 Mary

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Posted 16 October 2012 - 01:14 PM

[quote name="stevew"][quote] (3) they know their lady's butt is big, but for other reasons wholly external to the merits and drawback of a big butt, claim that it it not.
[/quote]

Oh my goodness!!!!! :rainbow:

Mary

#54 Renae Gage

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Posted 16 October 2012 - 02:54 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.


What is any review but someone's opinion? :question:

#55 Renae Gage

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Posted 16 October 2012 - 03:00 PM

interesting review, jim, and certainly deterring. your recommendation to choose a 6" SCT instead invites the conclusion that any achromat below ƒ/6 (or higher?) is a bauble for "the glassaholic who has everything."


Jim works hard to fit that description. :grin:

#56 jrbarnett

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Posted 16 October 2012 - 03:06 PM

Aww c'mon fellas! I been selling stuff! ~$5k worth of eyepieces thus far, and I'll get ready to do another tranche of 'em this weekend.

Just you wait 'til I get to the OTAs. You'll see.

My goal is to pick up Hubble cheap, given it's mounting maintenance costs and planned deactivation, and then use my X Prize competition entry to get up there and do a little cleaning and collimating and such. :whistle:

- Jim

#57 Renae Gage

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Posted 16 October 2012 - 04:38 PM

What do you think of that focuser, Jim?

#58 dakota

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Posted 16 October 2012 - 05:01 PM


What is any review but someone's opinion? :question: [/quote]

No ****! Well I guess us folks in South Dakota didn't know that. :foreheadslap:

;) ;)

#59 johnnyha

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Posted 16 October 2012 - 06:19 PM

The funniest part is when you actually read Larry's review you can see he essentally agrees with Jim, saying things like "Jupiter, always a demanding target for any telescope, showed a bath of purple surrounding its disc" etc. :grin:

#60 jrbarnett

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Posted 16 October 2012 - 06:22 PM

It's not a bad unit, Eric, but there is a little rocking/twisting on my unit during focus adjustment, which might not be so great for an imager. For visual, though, it works pretty well, even with decent sized eyepieces. The Long Pern on the AT scopes and others is a little bit smoother, but the SV might have a slight edge in load capacity. Pretty much a toss-up between the two.

I think the focuser is a good match for the scope and in fact has fit and finish a cut above the rest of the OTA. On the other hand, I think the $300+ Stellarvue is asking for these focusers standalone is ridiculous. For that money, a Moonlite or Feathertouch are a much better choice, but bundled in with a scope, it's a fine visual use focuser. I'm happy with it.

Regards,

Jim

#61 jrbarnett

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Posted 16 October 2012 - 06:23 PM

"Well I guess us folks in South Dakota didn't know that."

That explains a lot. I'll be giving charitable donations to SD public schools next year. Anything to help. Thanks!

- Jim

#62 jrbarnett

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Posted 16 October 2012 - 06:25 PM

You've met me, Bruce. You *know* I could use taller shoes.

:grin:

- Jim

#63 Gord

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Posted 16 October 2012 - 08:17 PM

The Pleiades has a small amount of CA using Siebert 24mm SWA's. Jupiter showed no CA whatsoever with my Pentax 8.5mm XF's.


This sounds like exactly the thing that Jim was commenting on earlier about people's comments about CA in scopes, especially ones that are for sure going to have boatloads of it. You may feel that there was no CA present, but there certainly was.

However, there do seem to be differences between people's sensitivity to it, and tolerance especially on a relative scale. If you don't have a perfect apochromatic view to compare against, a huge amount of CA next to a lot of CA may not seem all that bad. The effect is most noticeable when side-by-side.

I notice CA quite easily. My 6" F10 shows lots, especially on Jupiter. Still delivers a nice image with lots of details. And the more you look, the less you notice the purple haze. Alas, it's always there, and always degrading the image.

I remember one week a couple of years ago when a nice omega block moved in over the NE region. PERFECT skies for almost an entire week! The 6" achro was showing a beautiful image of Jupiter. One night, I decided to drag the 10" out as well since the views were so nice. That's when I realized how much was actually missing in the view from the 6". The CA was horrendous by comparison and there was so much more fine detail in the 10".

I guess that's the point of comparisons. Any well produced scope should perform great relative to what IT is supposed to do. But that doesn't tell you much until you look at it in context relative to what others do. I'm sure these fast achros do very nicely for what they were intended to do. They can do other things too, but planetary scopes they are not.

Clear skies,

#64 Gord

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Posted 16 October 2012 - 08:23 PM

Jim,

That's an interesting observation relative to the C6. I expect that your C6 is one of the more recent ones with Starbright XLT coatings?

Celestron's SCT's with that seem to be extremely bright I find. This is based on my own 3 samples with this. I expect the very good performance of these coupled with a slight loss of contrast due to CA at the very limit of detectability is what makes the little SCT edge out the fast achro.

I suppose there could be some kind of internal vignetting going on as well that you could check.

Clear skies,

#65 stevew

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Posted 16 October 2012 - 08:29 PM

My goal is to pick up Hubble cheap, given it's mounting maintenance costs and planned deactivation, and then use my X Prize competition entry to get up there and do a little cleaning and collimating and such. :whistle:

- Jim

We will all be looking forward to your review.
Make sure your review includes a test without the COSTAR :lol:

Steve

#66 stevew

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Posted 16 October 2012 - 08:30 PM

Johnathan, thats a great Moon shot, even with out the Chromacor.

Steve

#67 stevew

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Posted 16 October 2012 - 08:39 PM

A review by Terence Dickinson of the Canadian Telescope labeled version can be read here.
www.skynews.ca/PDFs/BigGlass_6inch-refractor.pdf

#68 John Miele

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Posted 16 October 2012 - 10:11 PM

...I felt that the Double Cluster wasn't showing as many stars as it should (i.e., looked surprisingly under-resolved for the aperture.


Jim, could you please explain in a little more detail just why you said this? Did you compare the view to another 6" scope and see more stars? Was there a certain magnitude you were trying to drill down to but could not see? I only ask because I also own the AT152 and just got done with three nights of viewing a variety of targets including the double cluster and this is the LAST thing I would have said. I felt like the tiny faint stars just went on forever in this cluster with a 17mm Nagler. I am very surprised at your statement. Please elaborate on how you drew that conclusion...thanks...John

#69 jrbarnett

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Posted 16 October 2012 - 10:31 PM

Howdy John.

First off, I was observing from suburban Sonoma county; a little farm owned by CNer cuzimthedad. NELM at zenith during the earlier parts of the session was ~5, with a fair amount of glow nearer the horizons. Transparency was average at the beginning of the session and got worse toward the end of the session.

It's possible that the cluster was nested in slightly lower contrast eastern horizon skies when I observed it in the AT152 and was higher and in less washed out skies when I observed it from home after unloading the car and setting up the C6. But countering that theory are the facts that my home site is a half magnitude brighter on average than the farm, and transparency was a lot worse after I got home.

But be that as it may, when I observed the cluster in the AT152 using a 27mm Panoptic (33x; 2 degree TFOV) and a 14mm Meade S2K UWA (64x; 1.3 degree TFOV), the star count seemed pretty low. That is, I'm used to saturation for the two clusters in 6" and above and the view through the AT152 looked more akin to what a 4-incher shows under suburban skies with dark lanes and gaps between stars.

The C6 from home showed the old Double Cluster that I know and love; which in a 6-incher hints at myriad stars within those gaps and channels between the brighter members.

Regards,

Jim

#70 dakota

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Posted 17 October 2012 - 05:40 AM

"Well I guess us folks in South Dakota didn't know that."

That explains a lot. I'll be giving charitable donations to SD public schools next year. Anything to help. Thanks!

- Jim


Don't look now but your immaturity is showing.

#71 johnnyha

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Posted 17 October 2012 - 06:22 AM

:gotpopcorn:

#72 t.r.

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Posted 17 October 2012 - 07:39 AM

This sounds like exactly the thing that Jim was commenting on earlier about people's comments about CA in scopes, especially ones that are for sure going to have boatloads of it. You may feel that there was no CA present, but there certainly was.

I think this is the reason Jim bought the scope and posted a review here. Many people were touting this scope as a planetary/lunar performer with little to no CA. The design facts didn't fit the claims and if Jim didn't buy one I was going to (they were sold out at the time). I thank Jim for purchasing the scope and taking the time to give his impressions providing another data point that people can use. I'm also happy that he saved me some money that I can spend on other gear! :p Hey, we all want a scope that is Da Bomb for the Buck...although a nice scope and quite capable, this one isn't all that! And this review or comments shouldn't be taken personally...which happens all too frequently here. :smirk: The hardest thing for a reviewer to do is to seperate themselves from emotion and remain objective.

#73 johnnyha

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Posted 17 October 2012 - 07:57 AM

Personally, I have never looked through a 6" f6 Chinese achro but I have looked through many 6" f8 achros and the chromatic aberration for me is intolerable - I'd much rather have a decent 6"" f8 dob. But then I'm a planetary/lunar guy, I'm sure the f6 achro is fine for deep sky as Jim and all the other reviewers have said.

#74 t.r.

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Posted 17 October 2012 - 08:27 AM

This scope may be Da Real Bomb... :dabomb:

http://www.cloudynig...5/o/all/fpart/1

#75 doctordub

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Posted 17 October 2012 - 08:42 AM

I have noted that the double cluster while slightly brighter in the 8" sct than my IM703 and AT152, more stars were resolved in the IM703, I need to do a side by side tonight with the AT152 and the 8" Meade sct.
CS
Jonathan


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