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Equipment Discussions >> Refractors

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teelgul
sage


Reged: 09/02/11

Loc: Australia
Re: Astro-Tech 60mm f/7 ED triplet, first report. new [Re: jrbarnett]
      #5492100 - 10/27/12 07:05 PM

congrats.looks cute and solid in styling. wish my np 101 were styled this way!! waiting for the shootout result. and may be a future shootout with the takFS60 CB!!
cheers


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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Astro-Tech 60mm f/7 ED triplet, first report. new [Re: teelgul]
      #5492144 - 10/27/12 07:27 PM

I used to have an FS-60C.

No longer, though. This is about it in the 60mm range for me I'm afraid.

- Jim


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MRNUTTY
Carpal Tunnel
*****

Reged: 11/22/11

Loc: Mendon, MA
Re: Astro-Tech 60mm f/7 ED triplet, first report. new [Re: jrbarnett]
      #5492180 - 10/27/12 07:57 PM

Jim, I'm not really up on all the apo jargon, so forgive the naive question, the only value the forth element in a quad apo is a field flattener? If so, and the AT2FF works with the EDT, then it would be better to buy the EDT for all the perceived pluses it has?

The EDQ was attractive from just the APO cost perspective. If the EDT has more pluses, the I'll switch my allegiance to the EDT. I'm in the market for a wide field refractor for AP. The AT72ED was finding a home as the sight scope for my dob.


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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Astro-Tech 60mm f/7 ED triplet, first report. new [Re: MRNUTTY]
      #5492329 - 10/27/12 10:01 PM

Y'know, I think it depends on the design of the quad in question.

The EDT is almost certainly an FPL-51 triplet similar to the AR111EDT (when AT uses FPL-51, they tend to say only "ED glass"; when they use FPL-53, they tend to say "FPL-53 ED glass"). At just 2.4" and f/7, even an ED doublet would be pretty well corrected for false color. This triplet should be overkill. We'll see soon enough. A little Barlowed Vega action should separate the men from the boys.

Regards,

Jim


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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Astro-Tech 60mm f/7 ED triplet, first report. new [Re: jrbarnett]
      #5492449 - 10/27/12 11:34 PM

We have first light and some comparisons.

Optically the scope is "just okay". I'd put it between 1/4 wave and 1/5 wave with some lower order SA. Good enough to be called "diffraction limited" in a spec sheet, but not good enough to stand up to the Carton, unfortunately.

Let's talk some specifics beyond the scope's star test. I used both Vega and Luna for false color evaluation. On Vega at 50x, the Carton shows just a hint of false color in focus. The AT60EDT shows plentiful false color outside and inside of (it's noticeably shorter depth of) focus; yellow-green on one side and magenta-violet on the other, but in focus at 52x it showed only an averted vision hint of ruddy haloing. I'd give the color correction edge to the triplet, but not by much; I just think that the triplet leaves less visually aggressive wavelengths unfocused, and to a lesser degree. This was confirmed bumping each up to 100x and 104x respectively; same colors, just in greater abundance.

Luna was interesting, too. Much like Vega, the triplet showed boatloads of false color on either side of focus, but in focus the image was almost color free (ruddy hint on the lunar limb only) at 52x and the same only moreso at 104x. The Carton behaved much as it did on Vega. More false color at 50x and 100x respectively, and of more common hue (violet), but...

Let me back up. The Carton is a meter-long OTA and was mounted on a Tak Teegul alt-az mount. I was observing on concrete. It was mid 70s today and mid-60s during the observations. The Carton's objective was roughly 6.5 feet above the ground for Vega, for reference. The AT60EDT was on a Nexstar SE. On Vega its objective was more like 4 feet off the pitch.

With that as context, Luna. The Carton was sharper and steadier. The slight rippling of thermals at the Moon's lower limb in the Carton was much more pronounced in the AT60EDT. Why? I'm not sure but I have a few theories. First, the lesser figure quality and shorter focal ration of the triplet allows it to suffer more from induced defocus than the slower, better figured Carton. The triplet, also, may not be fully acclimated yet. (Both scopes are out cooling until later, for a rematch). The proximity of the AT60EDT's objective to the heat rising from the ground, too, may help explain the greater apparent instability seen in the triplet versus the doublet. More later.

Switching gears, how about DSOs? It's a little "Moony" for that, but I went ahead and took a peak at M13 in each, at ~50x and ~100x. This is where it gets a little weird. The triplet is fully multi-coated with modern coatings. The Carton is single coated with MgFl on just one surface; leaving 3 surfaces uncoated. But...M13 was a bit brighter in the Carton than in the triplet, and also showed just a hint more granularity. Go figure. I don't make the news, I just report it.

Televue Plossls and an Orion Deluxe 2x Barlow were used in each scope. Vixen prism diagonals, too, were used in each. I tried to keep things as close as I could for the testing.

More to come.

- Jim


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johnnyha
Postmaster
*****

Reged: 11/12/06

Loc: Sherman Oaks, CA
Re: Astro-Tech 60mm f/7 ED triplet, first report. new [Re: jrbarnett]
      #5492458 - 10/27/12 11:46 PM

So... was the Federation Starship Fairie Queene also pink?

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teelgul
sage


Reged: 09/02/11

Loc: Australia
Re: Astro-Tech 60mm f/7 ED triplet, first report. new [Re: jrbarnett]
      #5492465 - 10/27/12 11:50 PM

Where do they say it's made or assembled ?

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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Astro-Tech 60mm f/7 ED triplet, first report. new [Re: johnnyha]
      #5492477 - 10/27/12 11:59 PM

No, actually. It was represented in luminous green on a text terminal, represented by the letter "F". The Enterprise was an "E", also green. This was awhile ago. The modem was the kind you plugged the phone headset into. 200 baud. Yee-haw, talk about fat-pipe.

- Jim


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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Astro-Tech 60mm f/7 ED triplet, first report. new [Re: teelgul]
      #5492482 - 10/28/12 12:02 AM

They don't say. But I'm pretty sure it's made and assembled in Taiwan. Long Perng looks to be the manufacturer.

Regards,

Jim


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Traveler
Pooh-Bah


Reged: 08/19/07

Loc: The Netherlands
Re: Astro-Tech 60mm f/7 ED triplet, first report. new [Re: jrbarnett]
      #5492665 - 10/28/12 06:03 AM


Nice report Jim.

Good to see that the Achromat is doing alright. How old is your Carton btw?


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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Astro-Tech 60mm f/7 ED triplet, first report. new [Re: Traveler]
      #5492877 - 10/28/12 10:26 AM

I built it up out of parts sourced from Sheldon Faworski who used to be a US astro-dealer. The Carton tubes came wrapped in Japanese newspaper dated 1980, so that's the best guess I have as to the vintage of the Carton optics I used.

Regards,

Jim


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Cyclop_si
professor emeritus
*****

Reged: 03/13/08

Loc: Slovenia
Re: Astro-Tech 60mm f/7 ED triplet, first report. new [Re: jrbarnett]
      #5492884 - 10/28/12 10:29 AM

Jim,

For strictly visual, which you would be your first choice, AT72 or AT60EDT?

Regards,


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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Astro-Tech 60mm f/7 ED triplet, first report. new [Re: Cyclop_si]
      #5492893 - 10/28/12 10:37 AM

Tough choice. Neither of the two have great optics, to be honest, but that could also be "luck of the draw" with me coming up on the short end. Based on my experience, I'd probably say "neither", but assuming there are some really good quality examples of the AT72ED and AT60EDT out there (i.e., mine are not typical), I'd probably go with the AT72ED for visual unless I needed the slightly more compact dimensions (due to travel needs, mount needs, etc.) of the 60mm.

The 60mm did do a bit better, to be fair, late last night after it had acclimated a bit more and the slab cooled. I'm going to move it to the taller mount tonight. I haven't given up on it, but I think my earlier verdict - good but not great optics - was correct.

- Jim

Edited by jrbarnett (10/28/12 10:39 AM)


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Eric Gage
Pooh-Bah
*****

Reged: 12/13/05

Re: Astro-Tech 60mm f/7 ED triplet, first report. new [Re: jrbarnett]
      #5493040 - 10/28/12 12:12 PM

Quote:



Let me back up. The Carton is a meter-long OTA and was mounted on a Tak Teegul alt-az mount. I was observing on concrete. It was mid 70s today and mid-60s during the observations. The Carton's objective was roughly 6.5 feet above the ground for Vega, for reference. The AT60EDT was on a Nexstar SE. On Vega its objective was more like 4 feet off the pitch.




Hold on there, partner. What were the prevailing winds? Were these observations before or after Happy Hour? Red state or blue state? Boxers or briefs?


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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Astro-Tech 60mm f/7 ED triplet, first report. new [Re: Eric Gage]
      #5493355 - 10/28/12 04:47 PM

Windless. Tea-totalled (almost; white Rhone blend at lunchtime; 6oz.). True blue state. Commando.

- Jim


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teelgul
sage


Reged: 09/02/11

Loc: Australia
Re: Astro-Tech 60mm f/7 ED triplet, first report. new [Re: jrbarnett]
      #5493396 - 10/28/12 05:18 PM

Quote:

good but not great optics - was correct.





silly question jim as you said earlier that you have sold your FS60.but based on past experience where would you place the Fs60 optics compared to the AT60. just to know the best in the 60mm range.
cheers


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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Astro-Tech 60mm f/7 ED triplet, first report. new [Re: teelgul]
      #5493439 - 10/28/12 05:48 PM

Of the three FS-series scopes I've owned, the FS-60C was the least well-figured, but still probably an order of magnitude better than this scope (figure ~1/6 wave on my 60mm Tak).

I also doubt that the ED glass used is FPL-51. My 111mm FPL-51 triplet is considerably better color corrected visually. I'm thinking this one uses something else.

- Jim

Edited by jrbarnett (10/28/12 05:49 PM)


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Ed D
Carpal Tunnel
*****

Reged: 04/30/10

Loc: Sunny South Florida
Re: Astro-Tech 60mm f/7 ED triplet, first report. new [Re: jrbarnett]
      #5493463 - 10/28/12 06:04 PM

Jim,

One thing I would be very interested in is your comparison of the AT R&P focuser to the Crayford used on the AT72ED.

Thanks for the good report so far.

Ed D


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Binojunky
Carpal Tunnel
*****

Reged: 12/25/10

Re: Astro-Tech 60mm f/7 ED triplet, first report. new [Re: Ed D]
      #5493571 - 10/28/12 07:25 PM

Looks a nice small scope, of course one wonders if its as good optics wise as say a TV60?,going by Jims assesment probably not, an interesting thing to ponder is that a lot of buyers can be(and not meaning Jim) seduced by a multi element design thinking that automaticaly you will end up with superb optics.Owning a ways back a triplet from one of the big names I found it gave colour free images as adverised however when cranking up the magnification even close to where it should perform it fell apart, a smaller two element ED I had would (yup I know its an overblown phrase) leave it in the proverbial dust,DA.

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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Astro-Tech 60mm f/7 ED triplet, first report. new [Re: Ed D]
      #5493581 - 10/28/12 07:33 PM

Hi Ed.

Re the focusers on the two AT scopes, last night I did have a chance to use a medium-large sized eyepiece (new 35mm Panoptic) in the AT60EDT. I have on many prior occasions used the 34mm Meade Series 5000 SWA on the AT72ED, which is a similarly medium-large eyepiece. Here are my impressions of the two.

I am still getting used to the new R&P. The lock knob seems to gradually add friction. When you get it very tight, the focus gets stiff and you can see the box-like assembly that surrounds the pinion flex and shift as you turn the knob. With the drag set so that the focus was buttery, the mid-large load would tend to slowly slip outward and defocus. With the tension set sufficient to hold the big load, the focuser motion was stiff in effort but still smooth in motion.

The Crayford on the AT72ED is a different beast. It is very smooth, but not that easy to adjust to carry the heavy load. When stiff enough to hold the eyepiece, focusing action is a little stictiony.

For visual use, both are decent focusers. I don't at this stage have a decided preference for one over the other.

- Jim


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