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Explore Scientific ED115 FPL53 115mm f/5.5 vs Skywatcher Esprit 120ED APO Triplet

equipment refractor imaging astrophotography
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#26 Vincenz79


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Posted 23 September 2020 - 12:31 PM

They are both owned by Synta. 

ok is this a good thing?

#27 YAOG



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Posted 23 September 2020 - 07:31 PM

ok is this a good thing?

Only because they are less likely to go out of business. It is certainly not because they produce the best optics. 

#28 Surfinash


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Posted 15 October 2020 - 01:20 AM

Congratulations on the new Esprit 120! I think it is a phenomenal scope, and a keeper.


I do however want to add a few things on how we evaluate the OTAs.


I read this thread, and I was in awe with how people get smitten with the external appearance and looks, and forget the rule#1 of DSO photography - the f/ratio impact.


If you are looking for a scope - your first, second, and third criteria should be "why am I buying this one for - visual, or AP"?


For visuals, an EdgeHD will beat ANY triplet hands down given the aperture, and optics, and focal length combination. You cannot beat an 11" aperture with a 120mm when it comes to visuals (why we all have our dobs and those precious EPs).


When it comes to AP - you have to strike a balance between the F-ratio, aperture, weight (for tracking), and available accessories.


So, an ES115 at 632mm focal length (FL) at f/5.5, is very different than the 120mm Esprit at 840mm FL at f/7.


Use a 0.8x reducer / flattener (they both will need one) - and you have a 500mm f/4.3 at 115mm aperture with ES vs a 672mm f/5.6 at 120mm aperture.


You see this difference? Essentially, with ES - you have two scopes in one, while with Esprit, the difference is not that significant when you compare objects through FOV calculators. In other words, the ES115 has greater applicability across the DSO spectrum.


I personally own an Edge 9.25, Teleskop Service (72mm), a Willams Optics (FLT132), and ES115 (besides a 10" dob and a Parks BAK4 15x80 bino for visuals). I gave a lot of thought over going with Esprit 120 and skip the 115 and 132. But the application that the 115 [and add the FLT-132 with 925mm FL] offers cannot be matched by 120, and the 120 would not allow me to cover a larger DSO spectrum.


So before I shoot any scope down on cosmetics and aesthetics - I would look at the applicability. 


[PS: the ES115 3.5" Hex focuser is solid, and works well].

Edited by Surfinash, 15 October 2020 - 11:33 AM.

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