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ES 127 AR vs ED APO 102mm f/7 for visuals

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#1 davidoux

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Posted 14 August 2020 - 03:01 AM

Hi all,

 

I am currently considering owning a godd refractor for the best possible visual experience,

I am really hesitating between the smaller ES apo vs bigger achro dilemna, what would you recommend for 

the best overall visual performance ? 

 

thanks

 

david



#2 beanerds

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Posted 14 August 2020 - 04:32 AM

I have an iStar 127mm f8 achromat doublet and a SW f9 ED100 and have had them out side by side many times and yes the ED100 is CA free compared to the iStar but there is a whole lot more to these 2 scopes  than CA .

 

#1 , the ED100 and Vixen SP mount can be carried outside and be observing basically straight away as one unit  , NOT ! the iStar on CI700 mount , 3 trips minimum ( and 3 after midnight ! ).

 

#2 , the ED100 is a good luna/planetary scope , the iStar is a GREAT !! luna/planetery scope . It just shows way more detail .

 

#3 , the ED100 is a good ( ish ) deep sky scope but the iStar is lots better , yes 27mm at this size level is a lot ! .

 

Overall the iStar shows all objects better if a little CA don't bother you but as #1 above says , be prepared to do a lot more work for the better views , but as you know ' Nothing is free in life ' 

 

I use them both about the same amount because of the ease of use the ED100 is used on work nights and nights of average seeing , but on weekends and holiday nights and nights of great seeing its the iStar 127mm that is used and with all the planets basically in the sky at this time ,  its the iStar that's getting used a lot more at the moment .

 

Both are good scopes that you are wanting , just be aware that CA can kill it for some people , it don't worry me much so please be aware of it , perhaps join a club and get a few views through scopes of the kind you are wanting before spending money and always wondering ,,,,,,  have I made the right choice ? ,, what if ??? etc.

 

Oh yes , welcome to CN's .

 

Beanerds.


Edited by beanerds, 14 August 2020 - 04:35 AM.


#3 markb

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Posted 14 August 2020 - 07:23 AM

Thanks to Beanerds for a really cogent discussion of the pros and cons on this pairing. My experience is all F5 or so, a horse of a different color (no pun intended, really). I had wanted to see a same-maker comparison for a while.

 

The f8-9 ratio makes all the difference; experience will vary if David, the OP, wants a short F5 tube. Color will hurt the achro at that ratio.

 

In any event, some of the contrast loss in any achro can be significantly cut by using a Baader LP 495 long pass filter. Because of the very sharp cut off, it more effectively reduces blue violet unfocused light and results in less overall light loss than the oft recommended Wratten yellows. I've used quite a few minus Violet type filters, and the LP495 is miles ahead of the rest.

 

If you end up with the achro, get it. I got mine after I sold the Jaegers 6" f8, which improved adequately with a Baader Semi APO or Fringe Killer, it would have improved significantly with the LP495.

 

The Jaegers F5 with the LP495 was remarkably improved, far better than regular yellow filters or the other Baaders.

 

Very cheap, even in the absolute.



#4 MalVeauX

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Posted 14 August 2020 - 07:57 AM

Hi all,

 

I am currently considering owning a godd refractor for the best possible visual experience,

I am really hesitating between the smaller ES apo vs bigger achro dilemna, what would you recommend for 

the best overall visual performance ? 

 

thanks

 

david

Hi David,

 

The extra inch of aperture (127mm vs 102mm) can matter for deep space objects a little, but frankly, gaining one inch of aperture to get more light is a compromise to having more chromatic aberration on brighter subjects (in the 127mm achro), like bright stars, planets, moon, etc, which is much better controlled in the 102mm ED scope (little CA to none on most objects). Personally if both were the same price, the 102 ED F7 would be the one to get in my opinion, it's just more versatile thanks to better color correction and longer focal-ratio relative to aperture size and can be great on all subjects without the loads of CA that will come with an achromatic doublet that is fast focal-ratio (coma, false color). Some are not bothered by CA, so for them, maybe the larger aperture would be appreciated. I am not terribly bothered by CA myself. A big aperture achromat can be great, for low power sweeping (such as 120mm F5), but to be versatile it has to have really long focal ratio to not be full of false color.

 

For best possible experience for size/cost, it would come from a larger mirror rather than these small refractors, such as an 8" newtonian or 10" newtonian.

 

If the purpose is small, light, portable, grab & go, the 102mm ED F7 (or longer) would be the way to go, with a good enough mount to handle it (Skyview Deluxe, Stellarvue M2C, etc).

 

Very best,


Edited by MalVeauX, 14 August 2020 - 08:06 AM.


#5 clearwaterdave

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Posted 14 August 2020 - 08:27 AM

I have both.,and the 127 shows more.,.period.,and "to me" the ca in the 127 is not enough to be noticeable.,The other factors are personal.,weight.,mount.,ect.,I can use the same mount for both so for me it's more of an enny meany as to who comes out to view.,



#6 davidoux

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Posted 14 August 2020 - 05:17 PM

I have both.,and the 127 shows more.,.period.,and "to me" the ca in the 127 is not enough to be noticeable.,The other factors are personal.,weight.,mount.,ect.,I can use the same mount for both so for me it's more of an enny meany as to who comes out to view.,

thank you all for the great feedback,

 

@clearwaterdave  I have a relatively dark sky , from my garden I can see quite a lot of stars but the horizon is obstructed by trees (donut area more or less)

I think in this configuration i will see more DSO than anything else, am I wrong ? 

how a dobsonian would compare to an AR127 for DSOs view ? I really want a refractor because i also want to to do day / nature observations but maybe dobs should be the better choice ...

 

thanks again



#7 gnowellsct

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Posted 14 August 2020 - 05:22 PM

Hi all,

 

I am currently considering owning a godd refractor for the best possible visual experience,

I am really hesitating between the smaller ES apo vs bigger achro dilemna, what would you recommend for 

the best overall visual performance ? 

 

thanks

 

david

Well you can get the 5 inch achromat and for $300 to $500 used get a c8 for apochromatic performance that will work on whatever mount you use for the achromat.  You won't have wide field views but you've got the achromat for that.  And a c8 will eat a four inch refractor for lunch on planets.  

 

Greg N



#8 clearwaterdave

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Posted 14 August 2020 - 05:31 PM

If you are saying your viewing will be higher up.,like 45* and up.,.a dob would be good.,beats sitting on a low stool like you would need for a refractor.,and bang for buck the dob will win.,and show you more.,You can use smaller refractors for daytime.,plenty of light for them..

  Maybe pick up an 8-10" dob.,and look for a small frac used nearby.,.good luck,.



#9 Jethro7

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Posted 14 August 2020 - 10:42 PM

Hi all,

 

I am currently considering owning a godd refractor for the best possible visual experience,

I am really hesitating between the smaller ES apo vs bigger achro dilemna, what would you recommend for 

the best overall visual performance ? 

 

thanks

 

david

Hello David,

One of my favorite and least expensive and biggest surprises is my Astronomics AT102ED. The performance of this little scope is amazing and has become one of my favorites for double star splitting and open clusters. It will give amazing Planetary views also. I cant say enough good things about this little scope and it is a bargain at $599.00. I often pair it with my Astro Telescopes 102mm F/11 Super planetary or my C8 Edge HD for viewing. These scope combinations compliment each other very, very well.

 

HAPPY SKIES AND KEEP LOOKING UP Jethro

 

20200809 032236
20200721 041636

Edited by Jethro7, 14 August 2020 - 10:44 PM.


#10 davidoux

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Posted 15 August 2020 - 04:25 AM

If you are saying your viewing will be higher up.,like 45* and up.,.a dob would be good.,beats sitting on a low stool like you would need for a refractor.,and bang for buck the dob will win.,and show you more.,You can use smaller refractors for daytime.,plenty of light for them..

  Maybe pick up an 8-10" dob.,and look for a small frac used nearby.,.good luck,.

thanks again its a good suggestion, i however have access to a much more dark and open view sky very close to my house (500 m ) where i could also do awesome terrestrial observations,I fear for portability with the dobson ..

 

also dobson availability is low currently and I am stuck in analysis-paralysis ... please help :) 


Edited by davidoux, 15 August 2020 - 04:30 AM.

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