Stat results: What are your 3 most used eyepieces?

Just in case anyone's interested, here are some rough summary statistics on what was posted in that incredible 3 most used eyepieces thread. With multiple entries, I usually selected only one set of 3 eyepieces, and that was for the dob... (personal bias). A couple of smaller refractors got dropped entirely if the longest focal length was something short, e.g. only 9mm. Clearly averaging choices together is fraught with problems, but here are the results anyway!

Average focal length for 3 most used -- 27, 14.9, and 8.2

Median for 3 most used -- 26, 14, and 8.8

We can use the results to pick a gold winner set!

At the high $$ end, it looks like a 26mm Nagler, 14mm UWA or Pentax XW, and 8.8 UWA!

Or a 27mm Panoptic, 14mm Pentax, and 8mm Radian.

For much less money: 26mm Meade Series 5000, 15mm Vixen or 13mm Stratus, and a 9mm Expanse or 8mm X-cel.

Obivously one's choices depend on the scope's focal ratio, tolerance for sky brightening, and the type of objects being viewed, but the choices were surprisingly similar and largely independent of scope focal ratio.

By the way, the SDs were 5.6, 3.1, and 2.4 Shows that there is definitely some variation. (This is partly because some picked a 30-35mm 1st then jumped to the 20-24 range which was other people's first choices)

Using ± 1 SD, we'd have about 21-33, 11-17, and 6 - 11 which reflects the variation and overlap in choices.

With many scopes on the market being from f/4.5 to f/6, the results have decided implications for eyepiece selection, especially vis a vis exit pupils!

The averages were 27, 14.9, and 8.2 and the median choices were 26, 14, and 8.8.

These results, coming from experienced observers, suggest exit pupils of 4 to 6mm for longest focal length; 2.5-3.5 for mid-range, and 1.5-2mm for higher. Which is close to, but also somewhat different from, conventional wisdom and advice.

If we settle into 5mm, 3mm, and 2mm (or slightly smaller), then that suggests:

8" f/6 scope (or 4" f/6) picking a 30mm, 18mm, and 12mm. (or 10.5mm)

10" f/4.5 or 14" f/4.5 picking a 21mm, 13 or 14mm, and 9mm. (or 8mm)

12" f/5 (or 80mm f/5) picking a 25mm, 15mm, and 10mm. (or 9mm)

(Probably would have to be 26mm or 24mm, 14mm, and 9mm or 10mm given the reality of the market-- not too many 15mm or 25mm eyepieces--at least not of the fancy kind!)

Oh, and for those small, delightful rich field scopes-- StarBlast, StarSeeker, and Astroscan:

4" or 4.5" f/4 or f/4.2 picking 20-21mm, 12-12.5mm, and 8-9mm.

---> Add in a 2x barlow and you'll have all bases covered. That would give you additional exit pupils of 2.5, 1.5, and 1!

Well, there is one more base... get a really long focal length eyepiece that gives you the widest true fov for your scope, even if it yields an exit pupil of 7mm or more. That one will be perfect for star hopping, the largest clusters, and sweeping the Milky Way. In the 1.25" format, candidates would be a 30-35mm Plossl, say the Ultima or TV Plossl (or 24mm Panoptic if you don't need the eye relief) . For the 2" format, a nice 32-40mm eyepiece, say a 32mm or 38mm Burgess or 35mm Panoptic or 40mm Pentax.

Hope this proves useful to someone. I'm revisiting my eyepiece selections right now!