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#1 Jond105

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Posted 19 September 2019 - 07:29 PM

How come it’s so hard to find just your regular run of the mill 2” prism diagonal. Mostly all seem to be you regular mirror? Does anyone know of any. I just would like to try a prism out.

#2 Don Taylor

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Posted 19 September 2019 - 07:40 PM

How come it’s so hard to find just your regular run of the mill 2” prism diagonal. Mostly all seem to be you regular mirror? Does anyone know of any. I just would like to try a prism out.

Unfortunately the choices are limited and the prices can get kinda high.  I guess it's harder to make a high quality 2" prism than a 2" dielectric - and all the APO folks like dielectrics due to their scope's shorter focal ratios - so a smaller market.  The least expensive 2" prism I've found currently for sale is the one from APM - also seen as an Altair. I use Baader T2 prisms but I would like to try a 2" prism as well.

 

https://www.outdoors...3_224881_1.html

 

https://www.altairas...m-Diagonal.html

 

There may be other versions (branding) of that unit too.

 

And of course there is the Baader Zeiss  ($$$$): https://agenaastro.c...sm-2456117.html


Edited by Don Taylor, 19 September 2019 - 07:45 PM.

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#3 Jond105

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Posted 19 September 2019 - 07:50 PM

Unfortunately the choices are limited and the prices can get kinda high.  I guess it's harder to make a high quality 2" prism than a 2" dielectric - and all the APO folks like dielectrics due to their scope's shorter focal ratios - so a smaller market.  The least expensive 2" prism I've found currently for sale is the one from APM - also seen as an Altair. I use Baader T2 prisms but I would like to try a 2" prism as well.

 

https://www.outdoors...3_224881_1.html

 

https://www.altairas...m-Diagonal.html

 

There may be other versions (branding) of that unit too.

 

And of course there is the Baader Zeiss  ($$$$): https://agenaastro.c...sm-2456117.html

Thanks for that Don, the Altair, depending on shipping, might be one to try. Unfortunately, still pricey to say the least. 



#4 wrnchhead

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Posted 19 September 2019 - 10:08 PM

This is an interesting possibility, it's just the body, maybe a mirror 2" one you already have would have parts that fit?

 

https://agenaastro.c...1c-2456005.html



#5 Don Taylor

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Posted 19 September 2019 - 10:25 PM

This is an interesting possibility, it's just the body, maybe a mirror 2" one you already have would have parts that fit?

 

https://agenaastro.c...1c-2456005.html

 

I have 2 of the Baader T2 prisms like the one you linked. Good performers.  You can install a 2" nosepiece and a 2" eyepiece holder but the prism clear aperture is only 32mm so it won't fully illuminate the longer FL 2inch eyepieces.

 

Both ends are T2 threaded (M42 x 0.75). Baader of course makes lots of accessories to fit - but I don't know of other 2" nosepiece or 2" eyepiece holders threaded to match (there could be - I just don't know of any).

 

The Baader T2 prism (the same prism as in your link) equipped with the 1.25" helical focuser and nosepiece is only $40 more and works very well. I like the helical focuser for a 'fine focus" in some of my scopes. Of course this diagonal is only 1.25":  https://agenaastro.c...1-2456005k.html  It's a really nice diagonal if you don't absolutely need 2".


Edited by Don Taylor, 19 September 2019 - 10:33 PM.



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