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SW Esprit 80mm for visual only?

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14 replies to this topic

#1 CounterWeight

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Posted 14 October 2019 - 11:54 PM

Just punched the ticket for one from our site sponsor Astronomics as it's still on sale. 

 

 

Yes, I know, you are supposed to ask before clicking.

 

 

... but I "need" something under the FS-128 doublet for true quick and easy viewing of wide field.  I really miss my Orion ED80T-CF but this has specs like the FSQ-85... ~F/5 TO ~F/5.5 which I did own but just imaged with.  Anyway this scope has interested me for a while and has 'penciled out' on specs for low power wide field.

 

Interested in any actual user comments?  I'd be using the ep's in my sigline.

 

Thank you.

 

 



#2 Jon Isaacs

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Posted 15 October 2019 - 03:25 AM

I have not used one. But.. It is F/5 and unlike the FSQ, it's not corrected for field curvature. Stars at the edge of the field will not be tight and round.

 

Jon



#3 Joku_

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Posted 15 October 2019 - 04:08 AM

Do they have too much field curvature for visual use? Usually your eyes can just adjust for field curvature...



#4 Jon Isaacs

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Posted 15 October 2019 - 05:08 AM

Do they have too much field curvature for visual use? Usually your eyes can just adjust for field curvature...

 

I calculate about 1 mm with the 26 mm Nagler.  The eye cannot simultaneously accommodate across the field of view.. 

 

This is essentially an apo ST-80.. It's not a flat field.

 

Jon


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#5 25585

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Posted 15 October 2019 - 08:42 AM

Just punched the ticket for one from our site sponsor Astronomics as it's still on sale. 

 

 

Yes, I know, you are supposed to ask before clicking.

 

 

... but I "need" something under the FS-128 doublet for true quick and easy viewing of wide field.  I really miss my Orion ED80T-CF but this has specs like the FSQ-85... ~F/5 TO ~F/5.5 which I did own but just imaged with.  Anyway this scope has interested me for a while and has 'penciled out' on specs for low power wide field.

 

Interested in any actual user comments?  I'd be using the ep's in my sigline.

 

Thank you.

Why did you sell the Orion?



#6 MrRoberts

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Posted 15 October 2019 - 09:04 AM

I just arrived in AZ for a 6 week astronomy session. I had recently purchased the Esprit 80 to complement my MOD 3 NV monocular. But for set up and testing yesterday with my C-8/E on an Ioptron AZM Pro mount I used TV Ethos 8 and 13mm's along with my Delos 4.5mm on the 80mm. Of course optically my C-8/E see's better(collimated well, aperture wins), but I have to admit that the views with the 80mm where sharp. Maybe at my age star deformation at the very edge is not observable. Tonight I will be working with my MOD 3 on it. I have both a 12 nm and 6 nm Ha filter for it.

 

I also use it as a nice little G&G on a TWL1 mount. I really likes the 8 Ethos and 4.5 Delos

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#7 MrRoberts

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Posted 15 October 2019 - 09:08 AM

I am even thinking of buying a CEM40 and doing some ap again with it.


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#8 areyoukiddingme

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Posted 15 October 2019 - 12:06 PM

I wonder if a visual field flattener will be compatible with this thing? I think it's Telescope Service that has one. 

 

I find it works pretty well on my 80mm F6.


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#9 CounterWeight

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Posted 15 October 2019 - 01:12 PM

Thank you all.

I've done a little searching for a visual flattener, and TS has one they call a universal flattener that they say works for visual as well as imaging. 

 

The package as sold does state it includes a 2 element field flattener, but it is in same press said to be for imaging.  I did not find anything visual for refractors at f/5 on the Astronomics site.

 

MrRoberts thank you for posting in and the images!

 

I do not remember the reason I no longer have the Orion, I may have gave it away as i sometimes do with small scopes if there is an interested 'younger person'... as i cannot find any correspondence about selling, that is most likely. have a rule about not holding onto 'unused gear' it was probably back in the days I had the FSQ-85.  I did like the optics and visual in it was great, but for imaging the FSQ-85 was just a vastly superior tool, triple that if there a bright star in the field of interest.

 

I do not plan on any imaging, visual only.

 

A lesson I learned with my big Dob (~f/4.6), I thought the views were great until i started using the ParaCorr 2, once you see the field corrected it's impossible not to see

(the issues) after that.  So the ParaCorr lives in my Dob.

 

Again, thank you for the replies.



#10 Jon Isaacs

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Posted 15 October 2019 - 06:08 PM

I just arrived in AZ for a 6 week astronomy session. I had recently purchased the Esprit 80 to complement my MOD 3 NV monocular. But for set up and testing yesterday with my C-8/E on an Ioptron AZM Pro mount I used TV Ethos 8 and 13mm's along with my Delos 4.5mm on the 80mm. Of course optically my C-8/E see's better(collimated well, aperture wins), but I have to admit that the views with the 80mm where sharp. Maybe at my age star deformation at the very edge is not observable. Tonight I will be working with my MOD 3 on it. I have both a 12 nm and 6 nm Ha filter for it.

 

I also use it as a nice little G&G on a TWL1 mount. I really likes the 8 Ethos and 4.5 Delos

 

Field curvature is a function of the eyepiece field stop and the scopes focal length.  The 13 mm Ethos shows less than half the 26 mm Nalger, the 8 mm, less than 1/5.

 

It's eyepieces like the 31 mm Nagler, 41 mm Panoptic and 21 mm Ethos that bring out the objectives curvature. The 31 mm Nagler shows about 1.7x the curvature of the 26 mm Nagler.

 

This is simply due to the wider field of view. 

 

Jon



#11 gnowellsct

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Posted 15 October 2019 - 10:14 PM

Well I don't know if it's helpful but here's the SW Esprit 80mm f/5 next to the Vixen ED81s f/7.7.

 

You would have to ask Jon about using an f/5 for visual he's our resident f/5 wide field specialist.  But as I recall he uses a Televue Petzval type scope for that and it's different from the SW Esprit 80mm.   (4 lenses achieve fast focal ratio and flatter field, though the scope is actually longer).     I think many people are in the camp that for visual use f/7 to f/8 is preferable.  But those who do refractor visual at faster ratios are a substantial chunk of the viewing public.  (And a huge number of Dobs faster still)

 

Greg N

 

vixen and skywatcher- cn size.jpg


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#12 SilverLitz

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Posted 20 October 2019 - 05:22 PM

Esprits can be used for visual, they come with diagonal, but they are very highly thought of as AP oriented scopes.



#13 CounterWeight

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Posted 21 October 2019 - 08:32 AM

Thanks Mark, agree, most of the results and reviews from my searches are about for imaging with the scope, and are favorable.  That is why I asked here about visual.  I know when I was imaging and had my FSQ-85 at the time I only remember looking through it once to see if it worked for that, which it did.  My goal was imaging which i then got about.



#14 CounterWeight

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Posted 24 October 2019 - 11:20 PM

The Esprit 80  is here and unboxed, the kit in it's case is well done waytogo.gif , the scope OTA and focuser construction appear substantial. What a compact little scope.  No chance to view through it for me in the next few days but have to say my initial impression of the scope / focuser build, case and accy's is all very positive. Will add more impressions after I get some saddle time with eyepieces.  Will not be attaching and using the included finder scope, but nice they include it, same for the foreseeable future the flattener.


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#15 Nippon

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Posted 26 October 2019 - 03:53 PM

I just arrived in AZ for a 6 week astronomy session. I had recently purchased the Esprit 80 to complement my MOD 3 NV monocular. But for set up and testing yesterday with my C-8/E on an Ioptron AZM Pro mount I used TV Ethos 8 and 13mm's along with my Delos 4.5mm on the 80mm. Of course optically my C-8/E see's better(collimated well, aperture wins), but I have to admit that the views with the 80mm where sharp. Maybe at my age star deformation at the very edge is not observable. Tonight I will be working with my MOD 3 on it. I have both a 12 nm and 6 nm Ha filter for it.

 

I also use it as a nice little G&G on a TWL1 mount. I really likes the 8 Ethos and 4.5 Delos

Very nice. Wish my garage looked that neat and orderly:)




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