Which eyepiece

[Casper99]

Hi all, While i am waiting for the skies to clear and get some use out of my

new scope, i thought i would look into what eye pieces i could start saving for.

I have looked and found on this forum a guide on how to calculate what size eps

i should get, but it is still quite confusing so a little help would be much appreciated.

With my scope as shown below my calculations have led me to this:

127 x 1500 = F11.8

High Power lens = 8.85

Med/High Power Lens =14.75

Med/Low Power Lens = 23.6

Low Power Lens =35.4

I am sure someone will correct me if these figures are incorrect but my question is

what actual sizes should i go for, as when i look, some of these sizes are not listed,

so do i go up or down in size to get as close to these figures, and will i need all of these.

Many thanks for your help.

[fredster]

One of the big bonus to owning a scope with a slow focal ratio like yours is that all eyepieces will work reasonably well. Even the cheap ones.

A 32mm Plossl is going to give you the widest field possible with your scope as you are limited to 1.25" eyepieces. Selecting a focal length lower (longer) than 32mm will not yield a wider field. So a 32mm Plossl would be a good choice and only cost from £20 new or £15 secondhand. Plus will compliment the 25mm that comes with the scope.

Something in the 16mm region would be good. One option could be the Rigel 16mm 80deg eyepiece. Its like a cheap (real cheap) Nagler and is absolutely avoided by anyone with a scope faster than F10. But with an F12 scope it works very well. I had one for a brief period, along with the 11mm version too. I was pleasantly surprised how well it worked and was great with my Skymax 102.

The William Optics SWAN eyepieces (and their many clones) would be a good option too. Like the 16mm above, they are avoided by the fast newtonian crowd but are great for the slow refractor, SCT and Maksutov owners. A 20mm would provide a good medium power with a nice field of view.

At the high end there is a ton of options. Plossls, Orthos, BST Explorer, TMB Planetary. All well priced offering good value for money. Each has a unique set of attributes depending on your likes and dislikes. But something around the 8-9mm mark would be good.

[Moonshane]

hi Richard

I think you are pretty much right with your estimates. I'd just go to the nearest available so perhaps 9mm (167x), 15mm (100x), 25mm (60x) and 32mm (47x). Another option is not to get the 9mm but to get a 20mm and a 2x barlow. This would give you 7.5mm, 10mm, 12.5mm, 15mm, 16mm, 20mm, 25mm, 32mm. One reason I suggest the latter is that you may find with such a long focal length you will benefit from different magnifications to cope with variable seeing conditions.