Antares Speers-Waler 18mm

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Brand and Model:	Antares Speers-Waler 18mm
Price ($USD):	$129.00
Type:	Misc Wide Angle
Focal Length:	18 mm
Barrel Size:	1.25 in
Apparent FOV:	70.0 degrees
Field Stop Dia.:	0.0 mm
Eye Relief:	13 mm
Elements:	8
Weight (lbs):	1
Description:

Vote Highlights

Antares Speers-Waler 18mm

Very poor edge performance, especially in short focal ratio scopes. Works reasonably well in an f10 refractor or SCT, but even at f10 the edge is very mushy. Caveat Emptor on this one.
Brian Redman
Katy,Texas

Overall Rating: 4
Weight: 1 (Unreliable Vote)
Date: 09/06/2001 06:16:00 am PDT
By: Anonymous (xxx.xxx.110.241)
Link to this vote: http://excelsis.com/1.0/displayvote.php?voteid=43176

Reply Replies: 0

Antares Speers-Waler 18mm

- very strong curvature of field. only central 65% of field is
sharp when focused at center.
- one must move the focuser about 3mm from the center-focused
position to get best edge focus
- it is not possible to focus the edge perfectly. Looks like
astigmatism
- center sharpness and contrast is comparable to 19mm panoptic.
- very slight barrel distortion. probably not noticable unless you
are looking for it.

Overall Rating: 4
Weight: 1 (Unreliable Vote)
Date: 05/08/1999 09:14:35 pm PDT
By: Anonymous (xxx.xxx.153.18)
Link to this vote: http://excelsis.com/1.0/displayvote.php?voteid=43174

Reply Replies: 0

Antares Speers-Waler 18mm

The 18mm Speers-Waler may look exactly like the 10mm, but the similarity ends
there. The 18mm is plagued by SEVERE field curvature. Star images cannot be
brought to focus at the center and the edge of the field at the same time - considerable refocusing is required! Not good...
This eyepiece also requires over one inch of additional in-travel on your
focuser compared to your garden variety Plossls.
This doesn't seem to be a random defect because I returned the first one and the second sample I got behaved exactly the same.
In addition to the field curvature, there is also considerable "barrel" distortion. The 10mm Speers-Waler doesn't suffer from either of these effects.
My conclusion: Skip the 18mm Speers-Waler and buy a 19mm Panoptic instead.

Overall Rating: 3
Weight: 1 (Unreliable Vote)
Date: 09/01/1998 12:48:47 pm PDT
By: Anonymous (xxx.xxx.40.174)
Link to this vote: http://excelsis.com/1.0/displayvote.php?voteid=43173

Reply Replies: 0

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