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Skywatcher 120ed ???

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#26 charen

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Posted 24 April 2013 - 04:35 PM

[quote name="vct123"]I owned an sw120ed, it was the older version before they switched to using schott glass for the crown element.
[quote].
Synta have always use Schott glass as the mating element with the FPL-53 in the Synta doublet EDs. In 2008 they just added a sticker advertising the fact as part of a deal with Synta. CA correction has always been the same.

#27 jrbarnett

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Posted 24 April 2013 - 10:04 PM

Have you looked at the Telescope Service 120mm f/7.5 FPL-53 doublet? Same Synta optics in a much nicer (looking and built) Long Perng tube assembly for a not ridiculous price if you don't live in Europe.

http://www.teleskop-...S-120-900mm-...

Exclusive of VAT, which you don't pay unless you're on Europe, the price is around $1800 at current exchange rates.

Just another option to put into the mix. I think it's a really pretty scope and if I didn't already have an AT111EDT, this would likely be the scope I would get in its place.

The other thing to be aware of is that some of the Synta 120ED OTAs are stopped down and do not enjoy the full 120mm of clear aperture. You can read about it here:

http://www.astro-for...ne-more-Equinox

Misplaced baffles reduced aperture to between 113mm and 118mm with no consistency unit to unit.

Regards,

Jim

#28 hfjacinto

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Posted 24 April 2013 - 10:11 PM

I have the Eon and it is an excellent scope. I use it for imaging, check out my gallery. The sw and Eon use the same optics, but I think the focuser is better on the eon.

#29 charen

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Posted 24 April 2013 - 11:22 PM

I measured my S.W ED120 Equionx [EON] at 117mm clear aperture. The 3mm loss did not concern me. It presumably cleaned up the peripheral image. Many binoculars have a greater reduced aperture. My now sold Oberwerk 100mm/45* BT's had a 91 mm clear aperture. The factory set front baffles clearly reduced the aperture. Still great optics.

Chris

#30 cjc

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Posted 25 April 2013 - 07:57 AM

I have a 120mm Equinox. It is only vignetted by the very long, 205mm, 2" draw tube. When the length of a 2" diagonal is added (112mm in my case) there is indeed vignetting for wide field eyepieces.

I estimate (misusing a diagonal calculator) that the clear field for an eyepiece with its focal plane at the eyepiece barrel shoulder, is only about 12mm in diameter. For a field of 27mm (maximum 1.25" eyepiece field) the outer rim will be vignetted by about 0.12 magnitude and for a 45mm field (maximum 2" eyepiece) by about 0.4 magnitude, or to about 70%.

I cannot verify the accuracy of the web based calculator, here, so I would welcome correction if the above is in error.

#31 Teal'c

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Posted 25 April 2013 - 04:54 PM

Have you looked at the Telescope Service 120mm f/7.5 FPL-53 doublet? Same Synta optics in a much nicer (looking and built) Long Perng tube assembly for a not ridiculous price if you don't live in Europe.

http://www.teleskop-...S-120-900mm-...

Exclusive of VAT, which you don't pay unless you're on Europe, the price is around $1800 at current exchange rates.

Just another option to put into the mix. I think it's a really pretty scope and if I didn't already have an AT111EDT, this would likely be the scope I would get in its place.

The other thing to be aware of is that some of the Synta 120ED OTAs are stopped down and do not enjoy the full 120mm of clear aperture. You can read about it here:

http://www.astro-for...ne-more-Equinox

Misplaced baffles reduced aperture to between 113mm and 118mm with no consistency unit to unit.

Regards,

Jim


Much appreciated, Jim.

Didn't even know this version was available. I do like the look of it over the SW.

Should there be any concern regarding vignetting in this offering?

#32 BPO

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Posted 25 April 2013 - 06:57 PM

Don't lose any sleep over the baffle issue. That linked article is the only place I've ever seen any mention of it. Many people immediately checked their own Synta/Orion/Sky-Watcher ED120s, but, to my knowledge, nobody was able to detect any similar problems.

It may well be that the issue was confined solely to that single sample under test.

And yes, as per charen, all Synta/Orion/Sky-Watcher ED optics of at least the last decade or so use the Schott glass. A decision was made to start branding them as such long after the glass was already in use.

As others have already said, it may be necessary to upgrade the focuser if you intend imaging or using heavy accessories. The stock Sky-Watcher Equinox (later sold in the USA as the Orion EON) focuser is usually adequate, although many replace it anyway, but the non-Equinox models may not be.

The Synta/Orion/Sky-Watcher optics are superb, and definitely superb value. VERY hard to beat.






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