Diagonal Dilema

[Caldwell 14]

I could really use some help here. After reading a few reviews for my Nexstar 102 stl and one of the Patrick Moore books "Choosing a Retractor" I went out like I was told and bought a 2" Diagonal, a Revelation as it goes and a GSO Revelation 2” 25mm eyepiece and the view is truly terrible, just awful. Very hard to focus, almost impossible. Round the edge of field is particularly bad, its all blurred. The nice tight pin points I had with my cheap and nasty eyepieces which came with the scope have gone and turned into nasty fat blobs for the most part. Where have I gone wrong? I have a Fringe Killer in but CA is worse in say M45 but much better at say, looking at the Moon. My fl is 6.5 BTW.

Is it

A: A cheap EP and should bin it! (and be quick about it)

B: Should have kept to 1.25 full stop.

C: Would be better putting a 1.25mm in the 2” Diagonal.

D: No idea mate your on your own.

I would like to buy one nice Eyepiece now and just get thing up and running again, suggestions would be really welcome, I don't know what to do and don't want to waste any more money

[FrankieValley]

I'm wondering if 2" EP's are not good for fast scopes. There is some discussion here about the issue - http://stargazerslounge.com/discussions-eyepieces/164240-any-point-2-ep-f-4-7-scope.html

I have a f/4.7 reflector and whilst the view is not rubbish with a 2" EP, it is if I put a 2" barlow in!

See if there is any difference between the 1.25" diag and the 2" diag with a 1.25" EP and stick with what is best.

I actually prefer 1.25" EP's as the view is right there in front of me and I don't have to crane my neck round corners to see to the edge ;-) I'm probably missing something, but heh :-)

[faulksy]

i have the same diagonal 2" revalations and find it great a few on here have them as well and say the same

[ronin]

I would have stuck to 1.25" eyepieces and diagonals. The choice of items in this size is so much larger, that unless there is a specific reason for 2" items the 1.25" market is more then adaquate. Also on your scope would adding a 2" diagonal and eyepiece not add a significant weight to the rear of the scope?

I have a 2" diagonal and a 2" eyepiece, 20mm Knight Owl, so far never used them in the last 5 years.

If you can fit a 1.25" eyepiece in the 2" diagonal then try it. Hopefully the views will return to being sharp. At least that would prove that there is nothing wrong with the diagonal being in the system.

If the views with a 1.25" are good then it seems the problem is with using a 2" eyepiece in the system.

As to one eyepiece the BST Explorers have good reputations. If you want wide views then the 25m is the obvious, although 1 eyepiece is a bit limiting. Perhaps the 18mm (37x) or 15mm (44x) may be a better choice. The 15mm will give a field of 1.5 degrees so enough for M42 and M45, hopefully enough for the alignment process, just not sure if you want more magnification.

[glowjet]

With a fast scope 6.5 fl, light rays form a steep cone to the focus point, so your focus is quite critical, there will be nothing wrong with the equipment you have purchased, just that you have created a wide field of view at the ep end for it all to be brought to focus, which is why you have a distorted edge of field, if you put a 1.25 ep into your 2" diagonal the problem should be solved, at least I think my theory is right, if not someone will soon shout

[Chris H]

The ep is ok, the diagonal is also of good quality. Try one of your 1.25" ep's that you know works in the 2" diagonal if this is ok it's the 20mm wide field of view that's the problem. Really though you don't really need the 2" diagonal on your scope 1.25" is fine.

[nightfisher]

try the 1.25 ep in the 2" diaginal, but you might not be able to bring it to focusl, i tried this with my st150 and did not have enough in travel with the crayford

[Caldwell 14]

Right thats settled it then, back to 1.25 it is... Just chucked the diagonal, 26mm eyepiece and Fringe Killer on ebay, someone is going to get a bargin