Pentax SMC-XW 3.5mm

5.0 Pentax 3.5 XW vs 3.5 Nagler

Excellent Eye Relief and Eye Point. Natural Colors

Size and weight can be cumbersome for smaller scopes.

A few months ago I purchased a Pentax 3.5mm XW even though I have a TeleVue 3.5mm Nagler. Although I enjoy the Nagler, I like the Pentax 10.5mm XL for Planetary and Lunar work so I thought I'd try the 3.5 XW. I've used and compared both 3.5mm eyepieces on Saturn, Venus, the Moon, and several DSOs over the last several weeks. As with my 10.5 XL the 3.5 XW is terrific for Planetary and Lunar use. IMHO the Nagler still prevails for high power DSO use.

The 3.5 XW does exhibit a bit chromatic aberration that becomes annoying in the last 10% of the AFOV, but it's actually less noticeable than in 3.5 Nagler (IMHO due to the narrower AFOV) With my DOB there is noticeably less pincushion distortion at the edge with the 3.5 XW, which makes images of the planets useable over 90% of the AFOV. Detail and contrast are close in both but the colors are cooler than in the TeleVue 3.5 Nagler, which makes Saturn look more neutral to me. While the over all light transmission seems about the same with both eyepieces, when used on Planets and the Moon, the Nagler does seem to do a little better on DSO, especially Nebula.

Over all the Pentax 3.5 XW is a little more comfortable to use on bigger scopes than the 3.5 Nagler owing to the better eye relief and positioning. On smaller scopes like my Tak FC-60, Oracle, or 76mm Newtonian the Pentax is too large and cumbersome so for size and weight reasons the Nagler wins out on these scope. On any of the scope 4" or larger this isn't and issue. In these scopes the Pentax is a pleasure to use.

The Pentax 3.5 XW is a definite keeper. If you're looking for a high power, wide FOV eyepiece I would certainly recommend checking it out.