My new 1.25 dielectric WO diagional

[ianB]

Hi,
I have had my new diagional for about a week now, looks very nice and comes in a nice box and works fine, but i thought i would just pass on info about one thing that i find annoying.
Whenever i change my eyepiece for another i find that as i place the ep into the diagional it sometimes catches on the ring inside, the ring that grabs and holds the ep in place, and in the dark i find this rather annoying trying to jiggle it into position and opening the ring wider, sometimes it is open wide but still catches.
No big issue but though someone may want to know.

ian

[Camelopardalis]

Just unscrew it more before withdrawing the eyepiece :D I'm guessing it's not outside the realm of manufacturing tolerances, but I use a bunch of ES 1.25" eyepieces with mine and I've not experienced this.

Seriously. There are some eyepieces, notably some televue ones, that have an annoying "safety" undercut...now THAT is annoying :mad2:

[Sarge]

Know the feeling Ian, happens to me occassionally as well. I usually happens if I don't insert the eyepiece perfectly vertical to the shaft of the diagonal it will catch. Rather difficult to be perfect in the dark, just have to be careful.
Dunk your right about TV eyepieces, the undercut can be annoying, but it has saved my eyepieces on more than one occasion.

Clear skies

Rod
:D:D

[Profiler]

I have had a love hate relationship with this diagonal design which is badged under many different names such as WO, Orion, AT etc. The compression ring is a cost cutting measure isn't of a particularly good quality and have encountered this problem on a number of occasions including the ring simply falling out as it doesnt retain its spring. Unfortunately, the big design flaw with these diagonals which cant be gotten around is the eyepiece coupling in the diagonal body which is actually smaller than 1.25.

So what does this mean? It means that the diagonal vignettes eyepieces around 22mm and above. So - don't buy this diagonal if you want to use it in the context of a small grab and go set-up wherein you would want to use EPs like the TV 24Pan etc.

Worse, the vignette creates a soft very distracting fuzz appearance in the eyepiece where there should be a crisp edge from the field stop. What is so frustrating about all of this is that otherwise these diagonals are excellent in terms of light-weight, well built, very reasonably priced (ie affordable) and have a good mirror:shrug:

[Astro_Bot]

It may help to continuously rotate the eyepiece left and right (i.e. CW and ACW) while inserting and removing - it helps with being gentle and keeping the eyepiece vertical.

Give it a go.

[ianB]

Interesting comments and experiences, yes i will need to insert the ep slowly and dead straight, still an annoying experience at times.

[anj026]

I agree with Profiler, these diagonals are great value for money and will be a match for more expensive diagonals most of the time. I have seen the vignetting using a 24mm Panoptic in an f6 refractor. The Tele Vue Everbrite is more compact but actually has a larger opening and does not restrict the light. It is 2 or 3 times the price though. :( This may not be a problem in a longer focal ratio scope. Certainly not a problem using eyepieces with smaller field stops. :)

[N1]

Very interesting comment Andy. I use the WO 1.25 on my 60mm f/5.9 refractor, and the 24 Panoptic and all longer FL eyepieces vignette as decribed. I don't find it terribly annoying, but would consider a TV Everbrite diag if that means full light to the edge of the field and a crisp field stop. does the Everbrite achieve this?

[anj026]

Yes the Everbrite does eliminate the vignetting. You are right it is a minor issue on the whole. The Everbrite is definitely a better diagonal but then it should be considering the price difference. I have used it with a WO 66SD and now with a TV 60 and the field stop with a Panoptic 24mm is crisp.

I can't say I have seen a difference in the performance when used with smaller field stops/higher magnification.