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Explore Scientific Refractors

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#26 barbie



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Posted 02 November 2019 - 09:29 PM

All of the brighter galaxies ARE viewable in a 4" aperture. These galaxies represent a pretty good cross section of the different types. All that's needed are dark, transparent skies.
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#27 Sketcher



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Posted 03 November 2019 - 02:34 PM

1. Is it worth paying extra for the ED model?


2. Would like a stable alt/az mount, or maybe an EQ mount. Any suggestions?


3. Would like an illuminated finder scope that can be mounted on the ES scope. Again, any suggestions?

1.  That's a tough ($500) question to answer.  Some people enjoy the performance-to-price ratio provided by the achromat, and are capable of gaining much pleasure through the use of such a telescope.  There are others who would consider it more worthwhile to pay more for the additional performance edge promised by the apochromat.  So it comes down to the individual, their expectations, how much disposable income they have, etc.


Personally, I've enjoyed the use of both types of telescopes and could easily be a happy camper with either; but there are plenty of others who would consider the purchase of any 102mm f/6.5 achromat as wasted money.  Some would even consider the purchase of any ES apochromat as wasted money. . .


2,  Alt-az mounts are better suited for terrestrial use.  Equatorial mounts (preferred by myself) are better suited for astronomical use.  But again, either can be used for either purpose.  Most important are smoothness of motions, ease of use, and "solid" (more or less jiggle-free).  If you get a mount that a manufacturer sells with a 152mm refractor, odds are very good that it would be solid enough for your visual use with a 102mm refractor.  Though some could get by (especially for visual use) with the mounts that some manufacturers include with their 4-inch refractors.


3.  Depending on tripod height and eyepiece height, a right-angle (preferrably correct-image) finder might be more comfortable to use than an otherwise similar straight-through finder. This is especially true for some of the larger refractors where a straight-thru finder might end up too close to the ground for easy use.  As for an illuminated finder, many people (myself for one) don't find them to be necessary nor desirable.  But as is nearly always the case, there will be others with other preferences.  We don't all observe in the same ways, nor do we all observe under the same sky conditions.


The ES finder mounting bracket on the telescope might make an ES finder/mount easier to attach to the telescope than a finder/mount of some other manufacture.   Unlike eyepieces, finder mounts can't always be swapped between telescopes from different manufacturers.  So I would begin my finder searches with ES -- at least when it comes to the mounting rings.

Edited by Sketcher, 03 November 2019 - 02:35 PM.

#28 gnowellsct



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Posted 03 November 2019 - 11:38 PM

OTOH plenty of people here are mono-scopic, that is, dedicated to one and only one type of scope (such as refractors), and the solo-mono-scopics, which is, those who will only use one type of scope (such as a refractor) and within that category one and only one scope that's it.


Well, this is the Refractor Forum; and, the OP is asking about two 4" Refractors.  Do you really expect an SCT recommendation?? 


Good lord talk about mis-reading a post.  I recommended a three inch class and a four inch class refractor, but also pointed out that they can fit in an expanded program.   --GN 

#29 Bomber Bob

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Posted 04 November 2019 - 10:28 AM

No, not a mis-read.  Your previous paragraph:  I would actually recommend an 80 or 92 mm scope.  Then when a year or two from now when the small aperture views of Jupiter leave a little hunger for something more, the user would have a scope that is fairly easy to mount on a c8, 9.25, etc.  And then together they may ride on a better mount.


IOW:  When the OP gets "serious" about observing, they'll want to move on to a large SCT.  A Reflector Fan could post something similar.


Again:  OP is asking about 4" refractors, not some 80mm or smaller APO to bolt on to an SCT later.  That arrangement works for you, but that's not what this thread is about.

#30 nva


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Posted 04 November 2019 - 04:09 PM

The worst part about es refractors is the three delrin grubscrews that wear out and get loose on the focuser collet. I have the same setup as P*.42 and can vouch for it's usability. The FPL 53 refractors seem to have some sort of thumbscrew, I was thinking about some nylon ones.

Edited by nva, 04 November 2019 - 04:10 PM.

#31 John Kocijanski

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Posted 07 November 2019 - 08:31 PM

Love my ES 102ED triplet.  Sharp views with great contrast.  Collimation is dead on.  It also does a nice job with DSOs considering it is only a four inch. 

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#32 sunnyday



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Posted 07 November 2019 - 10:35 PM

Hi. I am looking at the ES AR102 F6.5 Doublet Achro versus the ES ED102 F7 Triplet APO. My intended use is visibly looking at planets and some of the brighter celestial objects. No plan to do astrophotography. Seeking advice on three items pls.


1. Is it worth paying extra for the ED model?


2. Would like a stable alt/az mount, or maybe an EQ mount. Any suggestions?


3. Would like an illuminated finder scope that can be mounted on the ES scope. Again, any suggestions?


Thanks in advance.


yes ED almost no ca 

mount twillight 1 

finder scope  william optic as a red dot wow 

clear sky to you 

#33 tomb1


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Posted 23 April 2020 - 10:36 AM

I don't think anyone has mentioned the poor mans simple answer to CA issue present with an achromat.  Stop it down for planetary/lunar work.  Decreasing the aperture increases the focal ratio which is the reason for CA in the first place. I have an AR152 (6" achro) and when I want to do planetary I cover the objective with a paper plate with a 3" hole in it.  You would not have as much room for reduction with a 4" but I thought it worth mentioning.  We all don't have funds available for an apo just for planetary.  DSO's require as much aperture as possible and don't need an apo at all.  Fast apo's are great for astrophotography but are rather expensive solutions for contrasty, high contrast planetary visual.

#34 jimandlaura26


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Posted 24 April 2020 - 09:25 PM

If you want to look at planets you will be absolutely maxing out the magnification on a 102 to see any real detail, don't go smaller.

Get the AT102ED at the least.  I would never consider an achro for planets or the moon no matter what some people say.


I use the stellarvue M2C manual alt/az mount system (with add on handle) with my ES 127mm FCD100 triplet and it handles it fine until I pull out the massively heavy ES eyepieces I use (see sig) and then it takes a nose dive.  With an eyepiece in it moves fluid smooth and doesn't move when you let go.  Its not possible with the roller needle bearings it uses to lock it absolutely tight so you lose your target during eyepiece changes otherwise I like it.

I use the massive wide angle lenses I do so that even with my 5.5mm I can still super easily find targets with the red dot finder I use rather than trying to do a stable swap from a lower power eyepiece.

There is sorta a crap selection of manual alt/az mounts out there.


I would not be happy at all with less magnification than I have with my 127mm for planetary and I absolutely love how perfectly clear and false color free the views are.  I actually plan to get an Ethos 3.7mm to really max it out which at .49mm exit pupil will be the limit I think.


Also keep in mind with ES you have the "essential series" which are FCD-1 glass triplets an then the more expensive FCD100 triplets which color correct better but might be slightly overkill for pure visual (I like overkill however).


EDIT: Here is the full system I am talking about, I have only seen it available from Stellarvue.  You really do need all the parts anyways so its easier to get as a system.  It comes with the CGEM tripod from Celestron (actually ships in their box) which is very nice.  Seems to be on backorder.


Here is the way overpriced handle which should be included in the already expensive mount.  I bought it because I didn't like yanking on the scope itself to move it around.  Its super helpful at some angles and useless at others and a tad short but still usable with my 127mm.


Stellarvue also now has a variant of the M2C mount that uses Appleply wood. Which ever you get, it’s going to be rock stable. Good luck!

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