optic questions

Has anyone tried out the surplus shed plossl eyepieces?? if so what do they compare to??

what about their kits with the build your own instructions?

I have an 8" f6 dob.... How do I know which eyepiece over 26mm will work and which won't? Is there a way to calculate this??

On a tight budget like the rest of us..

Any help would be appreciated

Thanks

Mark V