eyepieces for a F5 focal ratio

[aerohound73]

Hi.I have a 200 mm reflector with a F5 focal ratio.I want to do planetary viewing using eyepieces at 11mm down to 2mm or 4 mm.I also want the eyepieces to have a FOV of 70-80 degrees.With the exception of Televue(far out of my price range), can someone tell what would be good eyepieces to buy that would work well in a. F5 focal ratio.I don't want to dish out big bucks for an eyepiece that doesn't perform well at F5.Thanks

[alan potts]

Any of the old Meade 5000 series UWA (82 degree) will be fairly good at F5. ExSc same 82 Series will also be good too. I am not sure how good your seeing is but 2mm eyepieces, apart from there not being many in my opinion will be too much power. The 4mm you were thinking of will give you X250 which even then will not be in the focuser all the time.

My advice is think long and hard about how much power you need, it is better to have a clean image than a blurred wobbley one. Maybe 3.5mm should be your top limit, but then the market is not awash with choice. You could also consider a barlow to reach the highest magification.

The 4mm slot if you go for that, could be filled by the W Optics 4mm 82 degree or the Skywatcher, which is much the same, if you can get it over there.

Alan.

[southernman]

I use a Meade 5000 UWA 6.7mm and an Explore Scientific 11mm (both 82 degree AFOV) in my 10" f/4.7 Skywatcher dob quite successfully. They both Barlow well and provide good wide field views with reasonable magnification.

Peter

[michael.h.f.wilkinson]

Much depends on what eye relief you tolerate. The Meade UWAs are great, and the Explore Scientifics should perform similarly, but their eye relief at the short end is way too short for me (I need to wear glasses). I would really consider whether 60 deg is not enough for planetary viewing. I find my Pentax XF 8.5 has sufficient FOV, and nice eye relief. Unlike the XWs it does not cost the earth. You could also have a look at Vixen LVWs (65 deg, 20mm eye relief).

[umadog]

I don't think you're going to be using a 2mm eyepiece on that scope. A 2 mm eyepiece will yield 500x, which is 62x per inch. The exit pupil will be 0.4 mm. Aim for the 4mm and see how you go.