45 Degree Erecting Prism

[MjrTom]

Hello all,

I was looking at picking up a 45 degree erecting prism so that i can use my ED80 telescope for some occasional wildlife watching.

The options I looked at were:

William Optics 1.25" 45° Erecting Prism

or

William Optics 2" 45 Degree Erecting Prism

Has anyone used one of these and if so do you have any feedback on them?

Looking at the options I cant see any justification with using the 2" one in the sense that a 24mm 1.25" eyepiece would give 21x which is about where spotting scopes tend to start. I would also be using my 10x42 bins for lower magnification.

Also the weight of the 2" eyepieces and prism is considerably heavier.

Would there be possibly issues with vignetting on the smaller prism.

Optically are they comparable?

Any suggestions of alternatives I should consider?

Thanks!

[johninderby]

Having used both I wasn't very impressed with the WO 1.25" one. Seemed a bit dim and only suitable for low power terrrestrial use. Wouldn't recommend it for astro use at all.

The 2" was a lot better all-round and could be used for some low power astro observing.

I've now ended up with this Omegon 90 degree 1.25" erect diagonal. Works well for an erect prism and can be used for terrestrial or medium power astro observing. I've used with an 80mm scope for terrestrial use and was very pleased with it. Price isn't to bad either.

http://www.astroshop.eu/omegon-1-25---amici-prism-90d/p,14172

John

[MjrTom]

Thanks John, just what I wanted to hear, although I was hoping that it would be positive

The one you linked to looks pretty good, only issue I can see is that its 90 degree which is awkward especially if for instance I was using it at the top of a sea cliff to view birds below then the eyepiece is going to be in an awkward position.

Maybe I should consider the 2" version if its that much better

[johninderby]

I used this version. Lighter than the pure 2" to 2" and it was very good for terestrial use.

1.25" 45 degree erecting prism with 2" barrel

http://www.green-witch.com/acatalog/William_Optics_Diagonals_and_BinoViewer.html

John

[MjrTom]

I used this version. Lighter than the pure 2" to 2" and it was very good for terestrial use.

1.25" 45 degree erecting prism with 2" barrel

http://www.green-witch.com/acatalog/William_Optics_Diagonals_and_BinoViewer.html

John

Mmm interesting a hybrid one sounds good. If the optical quality is upto scratch I might go for that then

[MjrTom]

Anyone else tried these prism diagonals?

Thanks!