Friday, 13 September 2019 | Joseph
Nice and Clear no distortions like pincushion or barrel in my SCT..PERFECT EP for viewing and finding..near as good as my former Pan 27mm..Quite remarkable value at f10 not tried yet at f5 but heard exc from other owners...recommended with NO reservations.
Saturday, 28 May 2011 | Andrew
The rule of thumb goes that you shouldn't use eyepieces that exceed a 7mm exit pupil, especially in telescopes with central obstructions. But rules are there to be broken, and being a young, rebellious chap (with quite large pupils), I decided to try out the 40mm in my f/5 and f/4.5 reflectors, giving 8-9mm exit pupils. I did not notice any central darkening and in fact got very pleasant views. I have to say it is one of the sharpest widefield 2" eyepieces I have tried, and performs very well even at these focal ratios.
Eye relief is pretty generous, but not too long as to cause kidney beaning - it is very comfortable to view through. Build quality is not up to the high-end standard, but is perfectly adequate. I very much appreciate the tapering barrel as it provides security without the likelihood of getting caught on compression rings. It is also small and light for a 2" eyepiece.
One curiosity I noted about the 40mm is the inability to fully accept 2" filters. They screw in about half a turn before jamming.
In summary, a fantastic sharp eyepiece with a very reasonable price tag.