Yet another EP query !!

[Rautospoon]

What is best for use in a WO Megrez 90 F558mm under LP conditions, for planetary and lunar observations:

TV 3-6 Nagler Zoom or just buying a single ("say" 4mm) Radian ?

The Zoom is about £100 dearer in the present TV sale, but just wonder if under UK viewing conditions it is worth paying the extra and would it get used enough ?

Many thanks

[catburglar]

I think the accepted wisdom says that a zoom eyepiece is generally not as good as a similar fixed focal length design. However, I've seen a few posts on here that rate the Nagler zoom very highly, and my own experience of the TV 24-8mm zoom was very positive.

Lunar and planetary observations are affected more by atmospheric steadinesss than by light pollution. I would think the range provided by the 3-6mm is almost perfect for your scope, provided your seeing conditions are not too extreme.

[John]

The zoom has the advantage that you can "fine tune" the focal length to suit the observing conditions which, as you say, can be vary variable here in the UK. Think of it as 4 eyepieces and the price seems much better value.

The Nagler zooms are in another league from other zooms, IMHO.

[dweller25]

What John said.

One thing I have learned is buy once and buy the best - the Nagler 3-6 zoom would be my choice.

[neilmack]

Is your telescope on a driven mount? If so it's difficult to see the case for paying for the wider field of a Radian.

My own choice for high power work are orthoscopics. The fields are on the narrow side (40 to 45 degrees) and eye relief is very limited, but they generally have high contrast (essential if you are suffering light pollution) and they are probably the sharpest of all designs. Those are the two key characteristics for a great planetary eyepiece. Have a look at the 'Circle T' (available in 4, 5 and 6mm focal lengths) and Baader Genuine Ortho (5 and 6mm) ranges.

And if you win the lottery tonight add the mega-£££££ Zeiss Abbe Ortho to that list!