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Old 10-05-2007, 08:26 AM
ausastronomer (John Bambury)
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Join Date: Mar 2005
Location: Shoalhaven Heads, NSW
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Quote:
Originally Posted by Dave47tuc View Post
Very nice indeed John. Like the case

Can I ask if you did not have the 31 Nag, or 27 Pano would a 26 Nag substitute for both of them?
Not really Dave. Firstly I can't use the 26mm Nagler T5 with my glasses on and take in the full FOV, which I like to be able to do. The "stated" eye relief of Nagler eyepieces is often slightly in excess of "useable" eye relief for many people, particularly for eyeglass wearers. I think they measure it to the top of the eye-lens, which can be recessed in the enclosure. Or something along those lines. At this focal length I am solely trying to maximise the FOV with good performance to the EOF, without an oversized exit pupil in the 18"/F4.5. I don't use this focal length for dim faint fuzzies where I would need superb contrast or high transmission, if I did I would have a 30mm Pentax XW, which clearly outperforms the 31mm Nagler in these areas. When I observe those dim faint fuzzies its always at a lot higher power.

The 27mm Panoptic doesn't get used in the 18" scope. It is the low power widefield for the 10" scope. It is a good choice for this because it is small and light and doesnt affect the balance of the scope. The 31mm Nagler does, as would the 26mm Nagler, considering it is balanced for smaller eyepieces. The 30mm Pentax XW would be a better choice in the 10" scope, but I can't justify selling the 27mm Panoptic to buy it. Particularly as I really only use the 10" for planetary and lunar and my 10 yr old normally uses that scope. I think for a 10yr old he is doing very well to have a 10" dob with Argo Navis and a 27mm Panoptic as his finder eyepiece. That 10" dob has also had a lot of time and money spent on it and is a long long way above standard. The thing is he is a very keen observer and loves it, so I don't want him to be held back with inferior equipment if I can give him good stuff.


Quote:
Originally Posted by Dave47tuc View Post
Also I had a 12 mm Nag T4 but I always found it a bit soft in focus, meaning I could never get a real sharp focus with it.
My 13 mm LVW seems a lot better than the 12 mm Nag I had
Something wrong with it, or it didn't match the scope you were using it in. Maybe, you should have sent it back and exchanged it?

While it is a tad soft at the edges in a short focal length reflector, it is still a very good eyepiece and only a small notch behind the 10mm Pentax XW IMO. When used in the 18"/F4.5 (2100mm focal length) it performs superbly.


CS-John B
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