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WO Zenithstar 103 vs TV 102iis vs TS Imaging Star 102

refractor astrophotography
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#1 vineyard

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Posted 17 September 2019 - 04:23 AM

Hello,

 

A new joiner here (who has learned a lot from the CN forums so thank you all).  Quick Q.  I'm thinking of adding an APO.  Idea being something that's reasonably portable, easy to set up, can do visual as well as AP, and is within the realm of the sensible wrt price & lead time.  So sadly no A-P or TEC or Takahashi (for the time being?).  AP will initially be DSLR based, but perhaps eventually CCD or CMOS (ie, the kit should be good enough to be able to support some personal growth!).  Something that can also eventually accomodate motorised focusing.

So I'd appreciate CN views on the following 3 potential choices:

WO Zenithstar 103 w flattener (f6.9 dropping to f5.5, 10:1 R&P dual speed focuser, FPL53 glass)
TV 102iis (discontinued so would be pre-owned f8.6, would need flattener, don't think they made these w FPL53 glass - perhaps ED?)
TS Imaging Star 102 (f5.1, FPL53,  built in corrector, would need special adapter diagonal for visual)

There are slight price differences between them of course, but perhaps they're roughly in the same range (+/- 30%).  If they were more or less the same price which one would be better?  I keep hearing about TV optics, but WO (w FPL53) plus flattener would outperform an ED TV wouldn't it? And would the TS outperform both b/c its a triplet?

All thoughts & insights gratefully received - thank you!



#2 Jon Isaacs

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Posted 17 September 2019 - 04:38 AM

TV 102iis (discontinued so would be pre-owned f8.6, would need flattener, don't think they made these w FPL53 glass - perhaps ED?)

 

Televue does not talk about glass types but given the performance of their doublets, it seems almost certain that they're based on FPL-53.  From a cost stand point, it makes little sense that they would have used anything else.  When you're paying $500 for an ED-80, the cost of the glass is significant.  When you're paying $2125 for a TeleVue 85 with optics made in Japan, it just doesn't make sense to use anything but the best.

 

I think the scope you want to consider is a used TV NP-101 IS or if you are using a smaller sensor, a regular NP-101.

 

Jon


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#3 Hesiod

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Posted 17 September 2019 - 05:58 AM

If are looking for a refractor having in kind to enjoy it also for stargazing, I suggest to skip "astrographs" (unless can try them, or have tested) because these may have a substantial amount of spherical aberration which, while basically meaningless for widefield AP, would severely undermine the visual performance.
I would skip also the TV102 because at f/8.6 is really slow photographically (and do not know about the availability of focal reducer): if are willing to purchase second hand, the NP101, as Jon Isaacs suggested, is "what you want" (btw, it is one of the few telescopes designed to be equally good for visual and AP).
Another interesting option could be a pre-owned Takahashi FC100 DF (even if could be rather pricey to get the photographic accessories): visually is very good, and the upcoming fc100 dz may lead some DFs' owners to sell their samples
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#4 M11Mike

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Posted 17 September 2019 - 06:14 AM

Agree with Jon and Alberto - while TV scopes have superb optics - the 102 is F8.8 --- primarily a VISUAL scope.  If you want VISUAL and AP - go for the TV 101....F5.4.

 

M11Mike


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#5 drd715

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Posted 17 September 2019 - 10:03 AM

http://apm-telescope...m/item/33303838

Check out this one as a comparison. Still doing some research on it myself, but it seems to be in the right size range for a quick use scope and comes with a case.

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#6 vineyard

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Posted 17 September 2019 - 06:10 PM

Thanks folks.  Jon I see from your signature line you have an NP101, so if you're ever selling... :)  And that's an intriguing idea re the Tak FC100DF - will look at that.  How would the WO optics quality compare to the TV (is it like fine wine - above a certain price level, my palate can't tell the difference: does the same apply for the difference between those optics?).  Cheers

 



#7 Spikey131

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Posted 18 September 2019 - 12:02 PM

The NP101 is good for visual or AP out of the box.  Optically, it is better corrected than the others.

 

The Tak will need an upgraded focuser and flattener for AP.  By the time you get it tricked out for AP, the price will be similar to the NP 101, at least used.  It is a really good fluorite doublet, but it is a doublet.

 

The WO is an ED doublet.  They have really nice focusers from what I have seen.  It is a lot cheaper.

 

The TS is an astrograph and really not designed for visual.  I guess you can adapt it for visual, but I don’t know how well that works.



#8 dscarpa

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Posted 18 September 2019 - 02:03 PM

 There's a A WO GT102 F 6.9 triplet with reducer and other goodies in Amart for $1,500. David



#9 Hesiod

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Posted 19 September 2019 - 07:46 AM

The DF's focuser is more than adequate for AP with a dslr or color camera; if plan to switch to mono+filters however may prefer to replace it with a motorized unit (IMHO simpler than modding the stock one).
It being a doublet is not a concern (CA is at bay for digital sensors, and SA will be likely extremely low for superb visual performances).
Its Achilles' heel is that photographic accessories are quite expensive and less likely to be found on the aftermarket so, unless find a deal for the whole package, may risk to have to pay much more than expected.
But if find a deal take note that it is a truly excellent refractor (it is so good that I kept my sample even after the purchase of the DL version)


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