I'm loving the on axis sharpness of the TAL for double stars & globs . . . will the Nagler be any improvement on axis in comparison?
TAL 24 vs Nagler 22
Started by jbarbour, 11/23/2004 01:09AM
Posted 11/23/2004 01:09AM
Opening Post
Posted 11/23/2004 01:32AM
| Edited 11/23/2004 02:07AM
#1
John,
I've not compared the two but I am pleased with the on-axis sharpness of the TAL 24mm in my 16" F4.5 dob. I've compared it with my 24mm axiom eyepiece which is quite sharp on axis and I can't see an appreciable difference. I don't find the off-axis aberrations of the TAL 24mm as distrubing as the axiom 24mm which has the characteristic edge astigmatism of the axiom line on fast scopes.
The TAL edge aberrations are subdued with the use of my GSO 2" barlow and you might consider using the combo if you have a fast scope.
I would also add that to appreciate the resolving power of longer focal length eyepieces such as the TAL 24mm, one benefits from eith a longer focal length scope or a larger aperature fast scope. Even though my 16" operates at 4.5 the focal length is sufficient to exploit the resolving power of the longer focal length eyepieces and unless one experiences the difference between smaller aperature fast scopes and larger aperature units, the difference is not realized by many observers. Even a 12.5" f5 appears to resolve sigificantly less with a longer focal length eyepiece than say a 16 f4.5 scope. I utilize the longer focal length eyepieces if seeing conditions are poor and I can still resolve planetary detail I wouldn't have even attempted in a lesser scope such as a 12.5" f5 unit.
I've not compared the two but I am pleased with the on-axis sharpness of the TAL 24mm in my 16" F4.5 dob. I've compared it with my 24mm axiom eyepiece which is quite sharp on axis and I can't see an appreciable difference. I don't find the off-axis aberrations of the TAL 24mm as distrubing as the axiom 24mm which has the characteristic edge astigmatism of the axiom line on fast scopes.
The TAL edge aberrations are subdued with the use of my GSO 2" barlow and you might consider using the combo if you have a fast scope.
I would also add that to appreciate the resolving power of longer focal length eyepieces such as the TAL 24mm, one benefits from eith a longer focal length scope or a larger aperature fast scope. Even though my 16" operates at 4.5 the focal length is sufficient to exploit the resolving power of the longer focal length eyepieces and unless one experiences the difference between smaller aperature fast scopes and larger aperature units, the difference is not realized by many observers. Even a 12.5" f5 appears to resolve sigificantly less with a longer focal length eyepiece than say a 16 f4.5 scope. I utilize the longer focal length eyepieces if seeing conditions are poor and I can still resolve planetary detail I wouldn't have even attempted in a lesser scope such as a 12.5" f5 unit.
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