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Equipment Discussions >> Refractors

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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Overdue First Light: Astrotelescopes 152 f/5.9 new [Re: dakota]
      #5473873 - 10/16/12 07:23 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


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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Overdue First Light: Astrotelescopes 152 f/5.9 new [Re: drollere]
      #5473877 - 10/16/12 07:25 PM

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



- Jim


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Gord
Carpal Tunnel
*****

Reged: 01/06/04

Loc: Toronto, ON, Canada
Re: Overdue First Light: Astrotelescopes 152 f/5.9 new [Re: dakota]
      #5474058 - 10/16/12 09:17 PM

Quote:

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,


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Gord
Carpal Tunnel
*****

Reged: 01/06/04

Loc: Toronto, ON, Canada
Re: Overdue First Light: Astrotelescopes 152 f/5.9 new [Re: Gord]
      #5474066 - 10/16/12 09:23 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,


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stevew
Now I've done it


Reged: 03/03/06

Loc: British Columbia Canada
Re: Overdue First Light: Astrotelescopes 152 f/5.9 new [Re: jrbarnett]
      #5474077 - 10/16/12 09:29 PM

Quote:


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.

- Jim



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

Steve


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stevew
Now I've done it


Reged: 03/03/06

Loc: British Columbia Canada
Re: Overdue First Light: Astrotelescopes 152 f/5.9 new [Re: doctordub]
      #5474079 - 10/16/12 09:30 PM

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

Steve


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stevew
Now I've done it


Reged: 03/03/06

Loc: British Columbia Canada
Re: Overdue First Light: Astrotelescopes 152 f/5.9 new [Re: jrbarnett]
      #5474090 - 10/16/12 09:39 PM

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


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John Miele
Carpal Tunnel
*****

Reged: 05/29/05

Loc: North Alabama
Re: Overdue First Light: Astrotelescopes 152 f/5.9 new [Re: jrbarnett]
      #5474182 - 10/16/12 11:11 PM

Quote:

...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

Edited by John Miele (10/16/12 11:17 PM)


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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Overdue First Light: Astrotelescopes 152 f/5.9 new [Re: John Miele]
      #5474210 - 10/16/12 11:31 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


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dakota
sage
*****

Reged: 12/11/11

Loc: SD (God's Country)
Re: Overdue First Light: Astrotelescopes 152 f/5.9 new [Re: jrbarnett]
      #5474531 - 10/17/12 06:40 AM

Quote:

"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.


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johnnyha
Postmaster
*****

Reged: 11/12/06

Loc: Sherman Oaks, CA
Re: Overdue First Light: Astrotelescopes 152 f/5.9 new [Re: dakota]
      #5474564 - 10/17/12 07:22 AM



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t.r.
Post Laureate
*****

Reged: 02/14/08

Loc: Upstate NY
Re: Overdue First Light: Astrotelescopes 152 f/5.9 new [Re: johnnyha]
      #5474643 - 10/17/12 08:39 AM

Quote:

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! 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. The hardest thing for a reviewer to do is to seperate themselves from emotion and remain objective.


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johnnyha
Postmaster
*****

Reged: 11/12/06

Loc: Sherman Oaks, CA
Re: Overdue First Light: Astrotelescopes 152 f/5.9 new [Re: t.r.]
      #5474660 - 10/17/12 08:57 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.

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t.r.
Post Laureate
*****

Reged: 02/14/08

Loc: Upstate NY
Re: Overdue First Light: Astrotelescopes 152 f/5.9 new [Re: johnnyha]
      #5474708 - 10/17/12 09:27 AM

This scope may be Da Real Bomb...

http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Board/vendorann/Number/5463445/page/0/view/collapsed/sb/5/o/all/fpart/1


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doctordub
Pooh-Bah


Reged: 01/11/06

Loc: New Rochelle, New York
Re: Overdue First Light: Astrotelescopes 152 f/5.9 new [Re: t.r.]
      #5474731 - 10/17/12 09:42 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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Mark Costello
Post Laureate
*****

Reged: 03/08/05

Loc: Matthews, NC, USA
Re: Overdue First Light: Astrotelescopes 152 f/5.9 new [Re: jrbarnett]
      #5474763 - 10/17/12 09:57 AM

Quote:

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





FWIW, I've counted about 100 stars in the Pleiades several times using a 4"F6.5 achromat (95-110 on individual counts). According to a 80s vintage edition of Telescope Handbook and Star Atlas, one should be able to see 105 stars (presumably with something like a 6" Newtonian)....

M45 is on its way to prime time location for evening observation. When it gets there, I'll have to do this with my 5" F6.5 achro....


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maknewtnut
Member
*****

Reged: 10/08/06

Re: Overdue First Light: Astrotelescopes 152 f/5.9 new [Re: dakota]
      #5474809 - 10/17/12 10:24 AM

Quote:

Jupiter showed no CA whatsoever with my Pentax 8.5mm XF's.





Opinions can tend to defy the laws of physics.


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dakota
sage
*****

Reged: 12/11/11

Loc: SD (God's Country)
Re: Overdue First Light: Astrotelescopes 152 f/5.9 [Re: maknewtnut]
      #5474858 - 10/17/12 11:07 AM

Quote:

Quote:

Jupiter showed no CA whatsoever with my Pentax 8.5mm XF's.





Opinions can tend to defy the laws of physics.




Whatever you say lol


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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Overdue First Light: Astrotelescopes 152 f/5.9 [Re: dakota]
      #5474891 - 10/17/12 11:30 AM

Correction: my "precious, erudite immaturity," if you please. I am only 11 years old, after all. That's how we grow 'em out left...er...west, pahtnah.

- Jim


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doctordub
Pooh-Bah


Reged: 01/11/06

Loc: New Rochelle, New York
Re: Overdue First Light: Astrotelescopes 152 f/5.9 [Re: dakota]
      #5474896 - 10/17/12 11:32 AM

You have seen the well defined CA on my Lunar images, but yet I have seen haze and thin clouds compleatly remove CA from the Moons Limb!
PS
Laws can be bent just like light.
CS
Jonathan


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