What makes a 2" wide field eyepiece suitable (or not) with a fast/slow scope..?

[Fishpaste]

I've read in various places that one eyepiece or another might not be suitable with a particular scope - because the scope is too fast or two slow...

So my question is how do I know if a particular eyepiece will work well with my scope or not - ie is it going to produce a good sharp image across most of the view.

My scope is an Orion XT8i 200mm DOB, focal length 1200mm... I think it's classed as f/5.9, is this classed as fast, slow or as I suspect, somewhere in the middle...?

[John]

The best way to get some idea whether an eyepiece, 1.25" or 2", will deliver sharp views across most of the field of view is to look out for reviews and reports of people using eyepieces in similar scopes. Some folks are more fussy than others about edge of field sharpness but after a bit of reseach the well corrected eyepieces start to stand out.

Usually, though not always, you need to pay more for eyepieces that are well corrected in faster scopes. At F/5.9 your scope is moderately fast and will "find out" some eyepieces that are not too well corrected but it's not so fast that you need to invest in Tele Vue eyepieces which are expensive but well known for being very well corrected eyepieces as they are designed and tested to work well down to F/4.

I would have thought the Explore Scientific or Maxvision eyepieces would work very with your scope and there are other choices too

[Fishpaste]

Thanks John.... I see, so it's basically the quality of the eyepiece that will make it work better in faster scopes, I assumed that there must be some formula (like working out magnification) that I was missing to calculate if an eyepiece was appropriate or not.