2" Eyepiece advantage

[matt c]

Hi all can someone explain the advantages of 2" fitting eyepieces apart from the advantage of a wider field of view do they collect more light from the secondary mirror or does it not make any difference? thanks

[russ]

You've mentioned the main and only real advantage. A 2" eyepiece has a much larger field stop (46mm versus 27mm for a 1.25"), which means the 2" eyepiece can have a far larger TFOV at the long end of eyepiece focal lengths.

But there's no advantage in using say a 15mm 2" 80deg eyepiece over a 15mm 1.25" 80deg eyepiece of equal quality. Absolutely none whatsoever. Unless you just want all your eyepieces to be a standard barrel size and no flaffing with adapters.

[matt c]

thanks for clearing that up for me mate. My scope came with a 2" adaptor and i'm itching to using it just not sure of the point

[russ]

It's well worth picking up a 2" eyepiece. I grabbed one of the Rigel 32mm Swan clones. It's a terrific finder eyepiece for my 8" dob giving a true field of view of 1.87deg.....that's large!!!!! It's makes finding most faint fuzzies a zinch with the red dot finder.

Edge correction is not the best but for some reason i do not find it a problem, yet strangely I find that sort of thing highly annoying in higher powered eyepieces.

[matt c]

sounds like a good idea then should keep my eye out when the time comes might get my hands on a descent second-hand piece

[russ]

Bought mine on Ebay for £21 delivered. They come up quite often on here and UK Buy'n'sell too. Perhaps not quite as cheap as that but still around £30 delivered.

Your Skyliner 250P would give the same true field as my Skyliner 200P......ie very wide