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Which 102 refractor?

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21 replies to this topic

#1 stars n planets

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Posted 21 May 2020 - 07:23 AM

Im looking at 2 refractors and would love some advice.

Skywatcher 100ed f9 evo
Altair astro 100ed f7 doublet


Both would be brought with a reducer and will go on a AVX mount.(no AVX mount bashing):) both around 4kgs with 1kg accessories going on.

Thanks
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#2 CharlieB

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Posted 21 May 2020 - 08:02 AM

Moving this to Refractors.



#3 SeaBee1

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Posted 21 May 2020 - 08:45 AM

I have the SW120 ED version and it is a very good instrument. Mine rides quite nicely on my AVX. And even at f/7.5, there is no detectable false color on moon or planets. The 100mm f/9 would have only slightly less light grasp.

 

SkyWatcher gets my vote...

 

Good hunting!

 

CB


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#4 db2005

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Posted 21 May 2020 - 08:46 AM

The Altair is using FPL51 glass. The SW ED100 f/9 uses FPL-53 glass and has a somewhat slower focal ratio. So, all things being equal, at least color correction and SA correction should (in theory) be better on the ED100 f/9. This, however does not say anything about other aspects of the relative qualities of the two scopes, including optical surface/figure quality. And the f/7 is going to be easier to move around due to its short length.

 

What are your preferences? Visual? Photographic? Solar system? Double stars?



#5 stars n planets

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Posted 21 May 2020 - 08:52 AM

The Altair is using FPL51 glass. The SW ED100 f/9 uses FPL-53 glass and has a somewhat slower focal ratio. So, all things being equal, at least color correction and SA correction should (in theory) be better on the ED100 f/9. This, however does not say anything about other aspects of the relative qualities of the two scopes, including optical surface/figure quality. And the f/7 is going to be easier to move around due to its short length.

What are your preferences? Visual? Photographic? Solar system? Double stars?

Photographic only:) mainly galaxies. I have my widefield scope already.

Edited by stars n planets, 21 May 2020 - 08:56 AM.


#6 YAOG

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Posted 21 May 2020 - 12:19 PM

Photographic only:) mainly galaxies. I have my widefield scope already.

Really no comparison, the SW 100ED is a much better scope optically. For imaging though the focuser may need to be carefully tuned or just upgrade to a better model. But for imaging I would look for an R&P focuser with less backlash and that could be automated. I think you can adapt most of the stepper motor autofocusers to the Synta focusers but I have not done it.

 

I had changed my Celestron XLT102ED and Vixen ED100Sf which are basically the same scopes as the SW 100ED over to 2" Feather Touch Crayfords for visual use and the focuser made a huge difference in observing pleasure to me.That said the Starlight Instruments 2" R&P and adapters costs more than the SW 100ED scope does used but it is a game changer and if and when you sell the SW 100ED the FTF can be removed and with an adapter change used on your next refractor.  


Edited by YAOG, 21 May 2020 - 12:19 PM.

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#7 Hesiod

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Posted 21 May 2020 - 01:28 PM

Photographic only:) mainly galaxies. I have my widefield scope already.


Neither of them would be my first pick, especially if plan to use a reducer too.
You will be mostly struck with widefield shots of galaxies at fairly low sampling.
If have a camera with small pixels may drizzle and crop but still...
In any case, if your mount/guiding can deal with its low speed (and have enough time to get a sound amount of subs) the 100/900 is IMHO a more interesting choice.
An f/6 CAT however would halve the integration time...

#8 photiost

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Posted 21 May 2020 - 01:43 PM

You must already be leaning towards one ...

 

Given only those two choices I would go with the Skywatcher 100ed f9  



#9 stars n planets

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Posted 21 May 2020 - 02:26 PM

You must already be leaning towards one ...

Given only those two choices I would go with the Skywatcher 100ed f9


I have a 60mm Altair triplet with a 0.8 FR at 340mm for widefield and F5.6. Sooo i was thinking the Altair 102 as ive been happy with the build quality
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#10 Rollo

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Posted 21 May 2020 - 07:40 PM

For imaging,, go with the faster scope and the best focuser.   waytogo.gif


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#11 stevew

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Posted 21 May 2020 - 08:29 PM

I've never been a fan of the Synta focusers, rings, and other hardware. I prefer the machined look and performance, But optically the Synta 100 F-9 ED has a great reputation.

So I'd go for an FPL53/Lanthanum  F-7 like this https://www.teleskop...n-Objektiv.html


Edited by stevew, 21 May 2020 - 08:36 PM.

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#12 mewmartigan

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Posted 22 May 2020 - 05:38 PM

I love my William Optics Zenithstar 103.
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#13 beanerds

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Posted 23 May 2020 - 04:24 AM

ED100 , mine is a real performer , taking 250x easily on good nights and I have only ever seen CA once and that was while looking at Venus a few weeks ago at 300x as it was getting lower in the west just after dark .

I only did it on a whim , just to see what I could see . Great optics in these scopes .

 

Beanerds .


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#14 BFaucett

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Posted 23 May 2020 - 04:33 AM

Astro-Tech AT102EDL  --  FCD-100 and Lanthanum f/7 Doublet

• dual-speed 2.5" Rack and Pinion 2” focuser

• .95 Strehl ratio minimum

https://www.astronom...-7-doublet.html

 

Bob F. smile.gif


Edited by BFaucett, 23 May 2020 - 04:39 AM.

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#15 YAOG

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Posted 23 May 2020 - 10:03 AM

For imaging,, go with the faster scope and the best focuser.   waytogo.gif

Why? So OP can capture the rainbows around all of the stars? 


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#16 Bomber Bob

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Posted 23 May 2020 - 11:55 AM

ED100 , mine is a real performer , taking 250x easily on good nights and I have only ever seen CA once and that was while looking at Venus a few weeks ago at 300x as it was getting lower in the west just after dark .

I only did it on a whim , just to see what I could see . Great optics in these scopes .

 

Beanerds .

Like you, I use my new AT102ED on a vintage Mizar (not Vixen) Super Polaris, with the MMD-II drive system:

 

AT102ED S25 (AR-1 & FC-50).jpg

 

With my Tak FC-50 riding along, this is my very best grab & go rig.


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#17 stars n planets

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Posted 23 May 2020 - 12:05 PM

So if FPL53 is a minimum the 102mm range is beyond my budget of £500-600.

So im looking at the sw ed80 which is fpl53 at 600mm fl with a field flattener. This may go well with my 60mm triplet which is 340mm?

Which is also within payload capacity with mounted simultaneous

Edited by stars n planets, 23 May 2020 - 12:07 PM.

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#18 Hesiod

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Posted 24 May 2020 - 04:31 AM

Maybe there is something eluding you, but do not expect dramatic differences going from 340mm to 600mm as far as galaxies imaging is concerned.

You will be anyway struck with low-resolution widefield imaging and will have to crop and drizzle a lot to shot at individual galaxies except M31 and M33 (by the way, the former may be too large to fit into a 600mm focal).

 

If want to shot a the other galaxies of Messier and NGC catalogues you want a focal over 1000mm, as fast as you can handle.

Popular choices were SCTs in the 6-8" range, to be coupled with the f/6 focal reducer for greater flexibility, or Newtonian/Mak-Newts* (but I would not use them on your AVX, at least those I deem fit for galaxies) but as of now there are many more options such as Cassegrain or RC reflectors

 

 

 

*the Skywatcher MN190 is a very fine imaging platform, but I would use with an eq6-sized mount


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#19 YAOG

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Posted 24 May 2020 - 02:48 PM

So if FPL53 is a minimum the 102mm range is beyond my budget of £500-600.

So im looking at the sw ed80 which is fpl53 at 600mm fl with a field flattener. This may go well with my 60mm triplet which is 340mm?

Which is also within payload capacity with mounted simultaneous

Yup, a decent 100mm FPL-53 triplet is out of money range for sure, easily double your budget.  



#20 stars n planets

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Posted 24 May 2020 - 04:00 PM

Yup, a decent 100mm FPL-53 triplet is out of money range for sure, easily double your budget.



Im very tempted with fpl51 version. I have till friday pay day to decide

#21 RichA

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Posted 24 May 2020 - 05:39 PM

Maybe there is something eluding you, but do not expect dramatic differences going from 340mm to 600mm as far as galaxies imaging is concerned.

You will be anyway struck with low-resolution widefield imaging and will have to crop and drizzle a lot to shot at individual galaxies except M31 and M33 (by the way, the former may be too large to fit into a 600mm focal).

 

If want to shot a the other galaxies of Messier and NGC catalogues you want a focal over 1000mm, as fast as you can handle.

Popular choices were SCTs in the 6-8" range, to be coupled with the f/6 focal reducer for greater flexibility, or Newtonian/Mak-Newts* (but I would not use them on your AVX, at least those I deem fit for galaxies) but as of now there are many more options such as Cassegrain or RC reflectors

 

 

 

*the Skywatcher MN190 is a very fine imaging platform, but I would use with an eq6-sized mount

Seconded. An 8" SCT OTA with a reducer corrector will give 1260mm at f/6.3.


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#22 beanerds

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Posted 25 May 2020 - 06:47 AM

Like you, I use my new AT102ED on a vintage Mizar (not Vixen) Super Polaris, with the MMD-II drive system:

 

attachicon.gifAT102ED S25 (AR-1 & FC-50).jpg

 

With my Tak FC-50 riding along, this is my very best grab & go rig.

Nice Bob , yes these Mizar mounts are very good , Very over looked but mine holding my ED100 sitting on a Celestron 2 inch stainless steel tripod takes some beating .

 

Beanerds .

 

ps. Don't mind the dent in the OTA ,, hence the $200 price tag lol.gif  .

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