[SkyWatch (Dean)]

Just to weigh in again: I haven't had the scope out for a while, but managed a really nice view of Saturn tonight. Very good seeing for once!

Some of the previous comments about coma in an f5 scope and the "unlikelihood" of a sharp fov with a planetary eyepiece like the Long Perng 5mm made me doubt my memory, so it was nice to have a chance to check. I understand the fov must deteriorate past the centre couple of mm due to uncorrected coma, but high power eyepieces only effectively use the centre of the field anyway. Coma is certainly present at the edge of the fov at low power, and that is where a coma corrector shines, but I must say I am not sure that one is absolutely necessary at higher power, even with an undriven scope like mine. Especially when one like the Paracorr can cost as much as the entire scope, and more than 10x as much as the cheaper high power eyepieces...

Tonight's viewing showed me the following:

The Long Perng 5mm showed a beautiful view at 300x (12" f5 scope), and I could see a sharp Cassini division and nicely contrasting cloud bands from edge to edge of the 60 degree apparent field, letting it drift in and out. The contrast and sharpness was perhaps slightly better at the centre, but it was very hard to notice any difference apart from a tiny bit of lateral colour near the edge of the fov: but almost all eyepieces show some lateral colour near the edge.

My Nagler T6 13mm (115x) was beautifully sharp and contrasty right across the 82 degree apparent fov.

I compared with a 6mm Vixen LV (45 degree fov, 250x), a 7.5mm Takahashi (50 degree, 200x), and a 3-6mm Nagler zoom.
All showed a beautiful, sharp image from edge to edge.

The Long Perng 5mm was certainly not put to shame, at roughly 1/2 to 1/4 the price of the others, and it has a wide enough fov to enjoy the view for a while before it drifts out of the field and requires moving the scope again. Much more so than (say) the Vixen. Its 20mm eye relief is a great asset as well if you have to use glasses- way better than a standard plossl. Well worth a look.

It would be nice to use a driven scope, especially at 300x(!), but because of the sharpness of the eyepieces it didn't really matter much at all if the image drifted off centre.

All the best,

Dean