Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

ES 127 APO vs. SW 120 ED APO

This topic has been archived. This means that you cannot reply to this topic.
14 replies to this topic

#1 Bill McNeal

Bill McNeal

    Ranger 4

  • -----
  • topic starter
  • Posts: 337
  • Joined: 07 Oct 2007

Posted 29 August 2013 - 03:25 PM

They are very close together in cost. The SW is a bit cheaper, has FPL-53 glass and includes accessories, but you get 7 more mms in the ES which uses a Hoya FCD1 (equivalent to FPL-51) triplet.

Has anyone done a head to head shootout/comparo? I'm torn between the two of them.

#2 Scott Beith

Scott Beith

    SRF

  • *****
  • Posts: 47,610
  • Joined: 26 Nov 2003

Posted 29 August 2013 - 03:30 PM

link Here you go.

#3 Bill McNeal

Bill McNeal

    Ranger 4

  • -----
  • topic starter
  • Posts: 337
  • Joined: 07 Oct 2007

Posted 29 August 2013 - 03:42 PM

Thanks Scott. But that thread refers to the AR 127, not the ES 127 APO, which is a more similar comparison.

#4 Scott Beith

Scott Beith

    SRF

  • *****
  • Posts: 47,610
  • Joined: 26 Nov 2003

Posted 29 August 2013 - 03:42 PM

Shoot - let me find the right link.
Sorry about that.

#5 Scott Beith

Scott Beith

    SRF

  • *****
  • Posts: 47,610
  • Joined: 26 Nov 2003

Posted 29 August 2013 - 04:00 PM

link one more try...

#6 jrbarnett

jrbarnett

    Eyepiece Hooligan

  • *****
  • Posts: 30,370
  • Joined: 28 Feb 2006

Posted 29 August 2013 - 05:03 PM

So here's the thing. I think those two scopes are indeed logical marketplace alternatives. The choice (for me) was even tougher when the really nice 120ED OTAs were still available (Sky-Watcher Equinox and Orion EON). The current Sky-Watcher 120ED's OTA is not as nice as that of the old Equinoxes and EONs using the same optics. In the meantime, they've improved the ES 127ED's OTA a bit by getting rid of the clunky dew shade and replacing it with a lighter weight, retractable one, so I think on the OTA mechanical and finish quality front, the ES 127ED now has an advantage.

I'd rate the color correction as being similar (with the 120ED perhaps doing a little better job by shifting more of the false color to the red rather than blue). The 120ED is a little lighter and a little less nose heavy, and therefore a little less demanding on the mount. As a doublet and an optic with less glass (it's smaller in diameter), the 120ED will cool more quickly than the larger ES triplet.

So basically I'd say get he ES if you have a mount that can easily handle it (Atlas, CGEM, etc.) and if you're stuck with a lighter duty mount, go for the 120ED instead.

Regards,

Jim

#7 dvb

dvb

    different Syndrome.

  • *****
  • Posts: 6,771
  • Joined: 18 Jun 2005

Posted 29 August 2013 - 05:13 PM

I went for the 120ED over the 127 for most of the reasons Jim mentions - it is lighter and cools more quickly.

I'm not "stuck" with a lighter duty mount, but have two that would carry the 127 easily - the iEQ45 and the EQ6.

But, I have an AZ4 alt-az, which the 120ED rights nicely on for "grabngo" type nights.

I didn't need another heavy scope, I needed another lighter scope.

#8 hfjacinto

hfjacinto

    I think he's got it!

  • *****
  • Posts: 18,784
  • Joined: 12 Jan 2009

Posted 29 August 2013 - 06:17 PM

I have the 120 ED and think it's great

#9 tonyt

tonyt

    Vanguard

  • -----
  • Posts: 2,220
  • Joined: 01 Sep 2009

Posted 29 August 2013 - 06:17 PM

According to tests at astro-foren the later skywatcher scopes (Eon, Equinox, Black Diamond) with improved mating element are full apo's with regard to chromatic aberration and spherocromatism and optically better than the original 120ED's or the ES127 (which are not full apo's).

I have an ED127 triplet and it has nice optics but with a little CA (blue slightly out of focus). I haven't looked through the later Skywatcher ED's, but if price was similar I'd choose the skywatcher based on Mr Rohr's tests.

#10 John Huntley

John Huntley

    Gemini

  • ***--
  • Posts: 3,013
  • Joined: 16 Jul 2006

Posted 29 August 2013 - 07:10 PM

I think the Skywatcher ED80, 100 and 120 have always had the same glass in them. A deal later signed with Schott led to higher profile promotion of the use of their glass but I believe it's always been used for the mating elements.

#11 tonyt

tonyt

    Vanguard

  • -----
  • Posts: 2,220
  • Joined: 01 Sep 2009

Posted 29 August 2013 - 07:17 PM

I think the Skywatcher ED80, 100 and 120 have always had the same glass in them. A deal later signed with Schott led to higher profile promotion of the use of their glass but I believe it's always been used for the mating elements.


I could be wrong of course, but I believe the mating element was changed. If you look at the tests on astro-foren the Equinox/Eon have markedly better results than the earlier Skywatcher ED doublets.

#12 tonyt

tonyt

    Vanguard

  • -----
  • Posts: 2,220
  • Joined: 01 Sep 2009

Posted 29 August 2013 - 07:47 PM

I thought I should check that my memory wasn't failing so I've just been to astro-foren and noted the secondary spectrum figures for the Skywatcher Pro 120ED (old gold tubes) and Equinox.
Two samples of the Pro version had about 190 microns spread between the focus points of different colors, while two samples of the Equinox 120 had about 75 microns spread. One Equinox scope had a spread of only 22 microns and was designated a "super apo" by Rohr.

So I strongly suspect that the mating element was changed between the original and later versions.

#13 John Huntley

John Huntley

    Gemini

  • ***--
  • Posts: 3,013
  • Joined: 16 Jul 2006

Posted 29 August 2013 - 07:47 PM

This thread from 2009 covers the glass type issue. I don't believe it changed but the brand (Schott) has been given more prominence as a result:

http://tinyurl.com/pbjhtdm

I'll have another look through the Rohr tests on Synta ED scopes but I'm sure I've seen the older gold tubed versions with good reports on there in the past.

My old gold tubed ED120 is certainly an excellent performer - somewhat better colour correction and planetary and lunar contrast / detail than a nearby Meade 127 triplet at a star party last year :)

#14 Bill McNeal

Bill McNeal

    Ranger 4

  • -----
  • topic starter
  • Posts: 337
  • Joined: 07 Oct 2007

Posted 04 September 2013 - 03:19 PM

Celestron's website says the SW has ED Schott as well as FPL 53 glass.

On the other hand, the ES 127 has FPL-51 equivalent Hoya FCD1 but is a triplet.

Although the SW is lighter at 11 vs. 15 lbs for OTA weight, I think my ZEQ25 should be able to handle either. The SW is real nice considering it includes a 2" diagonal and RACI finder. But I'm leaning toward the ES for the extra 7 mm and the all-white finish. I need it to look good in my living room!

#15 John Huntley

John Huntley

    Gemini

  • ***--
  • Posts: 3,013
  • Joined: 16 Jul 2006

Posted 04 September 2013 - 06:45 PM

With the SW ED120 I think the mating element (the non-ED one) is a Schott glass type (don't know which one) while the ED one is the Ohara glass FPL-53.


CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics