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Longest FL and Widest FOV in a 1.25" ep?

Started by cheepnis, 01/15/2006 12:34AM
Posted 01/15/2006 12:34AM Opening Post
I know that a 40mm plossl becomes barrel limited in a 1.25" resulting in a smaller FOV. The longest "wide field" pieces I have seen are in the 20mm area.

Does anyone know of a longer FL wide field ep in 1.25"

For use in an ST80 clone with only a 1.25" focuser. I currently like the view in my 32mm plossl and I own an old Orion "Ultrascan" in 19mm. Just wondering if I can go bigger.

Thanks
-Tim

8O [COLOR="Navy"]Turn a Kid on to Astronomy [/COLOR] 8O

Scopes:
C8plus, w/byers, f/10 and f/6.3
C5 on photo tripod, f/10 rarely f/6.3
6" f/10 newt on GEM, rare planetary nights
Apogee 80mm f/5
"ball style" 114mm f/4.5, camping/kids scope
Posted 01/15/2006 02:13AM #1
A 32mm plössl with a 50º afov will give the widest fov in a 1-1/4" ep.
A 24mm Panoptic at 68º afov gives the same fov.
A 20mm 80º afov ep would give very nearly the same fov but I don't know if such an ep exists in a 1-1/4" format.
Hope this helps,
Bob

Fujinon 10x70 FMT-SX binocs
Tak FS-78 ƒ/8.1 - 630mm fl.
6" ƒ/6.5 homeground newt. - 981mm fl.
10" ƒ/4.85 homeground dob. - 1231mm fl.



Posted 01/15/2006 04:00AM #2
Tim,

I've heard that the 35mm Celestron Ultima is able to squeeze out a tiny bit more true field of view than any other 1.25" ocular. However, you have to put up with rather long eye relief and a less than huge apparent field.

Dave Mitsky

Chance favors the prepared mind.

De gustibus non est disputandum.
Posted 01/15/2006 06:08PM #3
Thanks to all who chimed in.

It looks like I pretty well have it covered.
The 32mm Plossl at 50 deg AFOV, for the largest TFOV, and a very flat field.

The 19mm UltraScan at 77deg AFOV, for the "spacewalk" effect in a slightly smaller TFOV, with higher contrast and some slight softening at the edge.

The 24mm panoptic is out of the question ($ wise) for now, sigh.

Maybe I should just upgrade to a 2" scope, eh? Then I can use my GSO 42mm superview, which I love in my c8 (at f/10 and f/6.3) BTW.

Thanks Again.
-Tim

8O [COLOR="Navy"]Turn a Kid on to Astronomy [/COLOR] 8O

Scopes:
C8plus, w/byers, f/10 and f/6.3
C5 on photo tripod, f/10 rarely f/6.3
6" f/10 newt on GEM, rare planetary nights
Apogee 80mm f/5
"ball style" 114mm f/4.5, camping/kids scope