The Plossl class of eyepiece is saturated with offerings from all different companies and all different shapes and sizes. Any Plossl will do the job but if you are willing to spend a little extra you can own a Televue Plossl, which will outperform nearly all other similarly focal lengthed Plossls. It does mean parting with £70 which may seem extortionate for a Plossl but once you’ve gotten your first look through it you’ll know where that extra money went.
Televue have used 4 lenses (or elements as they’re sometimes known) in this Plossls design. Using only 4 elements makes for clearer views, untainted by the addition of potentially image degrading extra glass. The downside of so few elements is a comparatively small field of view, 50 degrees, which is on the small side even amongst it’s fellow Plossls.
From a comfort point to view the Televue is good, the 25mm has 17mm of eye relief (eye relief being the distance one can move ones head away from the objective lens). 17mm means it’s not only comfortable to look through but also suitable for eye glass wearers. The objective diameter is reasonable for a 25mm eyepiece.
The 25mm really takes off in it’s optical performance. At this long focal length the Plossl will get the majority of its use on nebula, galaxies and large star clusters. As such it is imperative that Televue wrestle as much contrast out of this eyepiece as possible. The lens edges have been blackened to achieve this end and one of the most striking aspects of the 25mm is its high contrast, making it easier to detect faint and elusive deep space objects. Also the field is beautifully flat which comes in handy when viewing loose open clusters in particular.
The whole of the field remains tack sharp with no image degradation even in the extreme outer fringes and there is no light scatter to speak of even on faster telescopes.
To summarise, the magic of this little Plossl is definitely in it’s optical performance. Views remain crisp and well defined across the entire field, there is no spurious light or other aberrations to speak of. This may be a more expensive Plossl but one that easily justifies its significant price tag. A definite recommendation if you can bare to part with your hard earned cash, but if you do it will be well worth it.
