Telescope Reviews: Re: Hyperion Zoom with FL Reducer on 8 SE

Sorry for weighing in late but upon coming across this thread, I've done some actual testing with the Baader Hyperion 8-24mm zoom (my favorite EP) and Celestron f/6.3 focal reducer with the C8 and these are my findings:

From my personal observations and estimate with the Hyp zoom, there is a marked reduction of fov from 20mm (where the fov is very much like my Televue 20mm plossl) going to 24mm. On the other end, there is that marked increase in fov from 12mm going to 8mm where the fov opens up real wide to give an immersive porthole wide view which looks more like 70ish than the published 68-deg max. In-between there is just a gradual increase/decrease of fov depending on where you're going.

With the f/6.3 focal reducer installed and using the standard diagonal, the view at the 24mm setting on the Hyp zoom shows an estimated 30 to 40% increase in fov as compared to the FR not installed. Of course there is the usual decrease in magnification when the FR is installed. But by my estimate, if at 20mm the fov is very close to that of a Televue 20mm plossl and if the TV 50-deg published fov were to be assumed to be the actual fov of the Hyp zoom at 20mm, then I would say that at 24mm the actual fov of the Hyp zoom may be less and is maybe around 45-deg only.

In conclusion, with the FR in place, the actual fov of the Hyp zoom at 24mm would roughly be around ~60 deg only, not really much and still cannot be considered as a "wide-field" view in the normal sense of the word. This is the reason also why I opted to get a dedicated Hyperion 21mm - to offset the relatively narrow fov of the zoom at these focal lengths. Hope this helps.

Best,

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Hernando
Nexstar 8/CG-5 ASGT; WO Megrez 102ED SV; Antares 6" 1529; WO ZS66SD; Orion ST80
TV Naglers 5T6, 9T1, 12T2; Panoptic27; Hyperion 8-24mm Zoom,21mm; WO 7.5-22.5mm
BO/TMB 2.5/3.2/4/6mm;UO HD 5;BGO 6;Meade-RGO 7;UO-V 9/12.5;Brandon 16mm;Ultima18
TV 2x,3x barlow&8/11/15/20/32plossl; Aspheric31;Siebert36-OB;Paragon40;Meade56Smoothie
C-f/6.3FR;OIII,UHC,SkyGlow,U-block,8"S-flter;GLP/Telrad/MRF/9x50RACI; NexImge;Canon RebelXS

Edited by ibase (07/04/09 05:02 AM)

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