telescope eyepiece size?

Question

Hi, I currently have a 26mm orion sirius plossl eyepiece and I'm wanting to add another to the roster. Night Watch by Terrence Dickinson said you should have at least 1 eyepiece from the 40-20mm range and 1 from 13mm-19mm and 1 from 4mm -12mm I'm looking at the orion epic line because of the ED optics and the wide exit pupils and good eye relief but I'm not sure which one would be better the 14mm or the 18mm. which do you think would best complement my 26mm I already have and why.

Answer 1

I'd go for a shorter focal length eyepiece and fill in the middle range later. With my f/5 dob, my most used eyepieces many nights are a 30mm and a 9mm. What will work for you depends on what you like to observe and what telescope you have. For deep space objects, I like an eyepiece with a focal length about 2x the f ratio of the telescope, so 10mm for an f/5, 20mm in an f/10. For planets, I like something that will give 175x to 250x, depending on aperture, conditions, etc. Your maximum usable power is limited to about 50 power per inch in a smaller scope and maybe 300x or so (depending on seeing) in a larger scope.

Answer 2

If you only currently have a 26mm then I'd actually say, get a high quality 2x barlow.

This will make your 26mm into a 13mm while preserving the comfortable viewing features that the 26mm has.

Answer 3

if you already have a 26mm then i would go with the much smaller 14mm because although the 18mm will magnify much better than the 26, its still somewhat similar, therefore i think you would enjoy the 14mm even more. and if you can go smaller than that, you should do do say a 9mm. thats just my opinon though. you are definately a smart man for going with good optics, nothing will make you want to veiw more than if you have good eyepeices. good luck!!!!!!!

Answer 4

I'd go for the 18mm, simply because if you ever get a X2 Barlow your existing 26mm can double as a 13mm.

Answer 5

You've left out an important piece of information: what is the aperture of your telescope?

A good rule of thumb is to start with one eyepiece which gives you a magnification equal to the aperture of your scope in millimetres, and one equal to the aperture in mm. divided by 5. Thus for a 200mm scope, the most used magnifications would be 40x and 200x.

I'd recommend looking at the Orion Stratus series instead of the Epics: they have wider fields of view and are generally a better quality eyepiece.