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TAL 24mm UWA 2” 92 degree AFOV eyepiece


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Summary:

TAL 24mm UWA is a high-quality eyepiece for low-power wide-angle scanning of the sky with emphasis on large open clusters such as Beehive, Pleiades, Hiades, Alpha Perseus.

Introduction:

TAL 24mm UWA is a compact 2” eyepiece with a straight, fairly narrow body and sloping top. The barrel is straight and well-blackened inside. The eyepiece is an 8 element fully multi-coated modern design. The manufacturer rates it at 80 degree apparent field of view and 12mm eye relief. It measures at about 92 degree apparent field of view, making it the largest AFOV eyepiece in current production. The mechanical build quality is adequate but not great – I rate it a notch below the lower priced BW-Optik 30mm 80 degree eyepiece. My sample had a very small chip at the edge of the housing that forms the opening for the top lens element. The first surface of the field lens is close to the focal plane, making TAL UWA sensitive to surface dust (this is only apparent in critical daylight viewing). The eyepiece weighs about 1 pound and focuses just a little further out than the BW-Optik. It has no eyeguard and comes with both end caps. The eyepiece is made in Siberia, Russia and is supposed to be the first of a three UWA series: 24mm, 20mm, 15mm. The eyepiece was evaluated with a Stellarvue Nighthawk (current production F:6), equipped with Williams Optics enhanced aluminum 2” diagonal. The author has no interest in the maker or distributor of the reviewed eyepiece.

Optical Performance:

Conclusions:

This eyepiece while flawed is more than the sum of its parts. Its weaknesses are field curvature and astigmatism, which are offset by excellent sharpness and contrast in the middle two thirds of the field of view. Telescopes of F:6 are about as low as you would like to use with this eyepiece. Lack of kidney beaning and pincushion distortion, coupled with a truly extended field of view makes this a very nice “porthole” eyepiece. It is sharper and contrastier then the BW-Optik in the middle, while more astigmatic then this eyepiece at the field stop. I was consistently less bothered by the levels of astigmatism and soft focus at the outer third of the field of view than I thought I should be (when viewing the outer image quality analytically). This eyepiece, while not cheap, represents good value for money and its competition would be University Optics Konig offerings. Unfortunately, I have not been able to compare it to those eyepieces as of yet.




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