Upgrading the 'free' diagonal and 1.25" vs 2" eyepieces

[Astral Enigma]

There doesn't seem to have been much said on this recently, so....

I've recently bought two new SCT scopes (Celestron Nexstar 6SE and VX GEM 925), each coming with their 'free' diagonal. It's been suggested to me that these are not, optically, that great and upgrading may be worthwhile. Of course there are many options, of those suggested to me the Baader SC Clamp system looks interesting because I understand that not only is it a 'big' optical improvement, it also offers more security for the eyepiece (can't just fall out by accident) and the means to use 2" eyepieces.

The second question is I'm trying to understand under just what cirumstances a 2" eyepiece will give a worthwhile advantage over a 1.25" one. I've now got a Hyperion 10mm eyepiece that can be used with either.

Does anyone have any thoughts! Thanks!

[Tinker1947]

A 2" diagonal will work better on low power EP's where some EP's only come with a 2" barrel, the Badder Click-Lock is so useful when swapping EP's in the dark with cold fingers, i have brought enough click-lock connector that nothing needs screwing in if swapping from a DSLR to a EP, all combinations are covered, if your just setting out collecting kit i would recommend the click-lock route......

couple of combinations....

[brantuk]

The 2" diagonals tend to give a very slightly brighter image - but the main strength is you can load 'em up with other accessories. They certainly hold cameras and bigger, heavier, eyepieces more solidly than the 1.25" ones, and on my Sct I found there's more clearance from the scope, which means I can get my fingers in to undo thumbscrews for changing eyepieces - always a problem with smaller diags. And of course they usually have an adaptor to enable use of both size ep's.

[Jim Steele]

I think they also give better eye relief and perhaps a wider field of view than standard ones

[rwilkey]

Hi AE, and welcome to the forum, the diagonal is a bit cheaper at FLO here: http://www.firstlightoptics.com/diagonals/baader-clicklock-2-dielectric-star-diagonal.html  I think there would be a noticeable difference when using this diagonal, not only optically, but handling-wise as well, it is so convenient just to give the lock one twist to secure your ep's.  On the 2" front, 2" ep's are very good as widefiend ep's and to get the most out of them ay low power 2" is better.  On using the Baader Hyperion as a 2" ep, I would say 'no'.  It is a 1.25" ep and if you remove the 1.25" nosepiece you end up with a different focal length at a lower power.  I have found that the Hyperion's do not really work well as 2" ep's, the views are fuzzy and slightly less defined.  No, if you are going to use 2" get a dedicated widefield 2" such as an Explore Scientific 82 degree series, the 18mm, the 24mm or even the 30mm monster.

[Astral Enigma]

Thanks for the thoughts so far. I'm still trying to get my head around it all! 

Last night was my first chance to try the Hyperion 10mm eyepiece and it was noticeable how tricky it was to do up the thumbscrews - which is where, as I understand it, the clicklock system gives a big advantage. Given that most of the better EPs are quite large, WHY on earth do they make the screws so short??? I had much the same problem with my 7-22mm Opticstar XL zoom...

By my calculation, the 2" EP should give about 3x the light of a 1.25" one, so in most circumstances must be better - or am I missing something?

[John]

....By my calculation, the 2" EP should give about 3x the light of a 1.25" one, so in most circumstances must be better - or am I missing something?

The amount of light is determined by the aperture of the primary mirror or objective lens, not the diameter of the eyepiece. The main advantage of the 2" eyepiece is that it can have a larger apparent field of view than the 1.25" ones. Eg: a 32mm 1.25" eyepiece will have a maximium of a 52 degree apparent field whereas my 31mm Nagler (a 2" eyepiece) has an 82 degree apparent field. The size of the barrel constrains the diameter of the eyepiece field you see.

The advantage of the larger field of view is that the more extended deep sky objects will fit into it. You are working with the same amount of light though.