Author Topic: Diagonal  (Read 1060 times)

Andy Pyatt

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Diagonal
« on: December 27, 2017, 08:02:57 am »
Hi,  does anyone have a 2 inch or 1.25 inch dialectric diagonal (99%) that she or he would like to sell cheap??  I need one (either).  Orion has a 1.25 on sale for $72 right now but thought I would reach  out to the club before buying this one.   Thanks,
Andy
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George B Grimm

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Re: Diagonal
« Reply #1 on: December 27, 2017, 08:47:43 am »
I heard you have a new scope.  It is an 8 inch sct?
I ask that because that would influence the type of diagonal you should buy.  If it is a sct then you should only buy a diagonal made for an sct with a screw on attachment. Not doing so and using the type that just slides in has the potential to scratch the glass of future attachments like focal reducers. On some SCT's with their local focal length aka high power  2 inch stuff just doesn't have the same impact as it does on short focal length refractors. I would get a nice dialectic 1.25 made for an sct. 
« Last Edit: December 27, 2017, 08:49:32 am by George B Grimm »

George B Grimm

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Re: Diagonal
« Reply #2 on: December 27, 2017, 09:12:38 am »
In searching for a 1.25 sct dialectic diagonal you know they don't make them.  So here is a real deal
https://agenaastro.com/gso-2-90-99-dielectric-sct-mirror-diagonal.html

I use agena alot.

Andy Pyatt

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Re: Diagonal
« Reply #3 on: December 27, 2017, 09:44:44 am »
Hey George, thanks for the info. It is an 8 SCT and I figured if I got a 2in diagonal I would also have to buy the two in adapter for the back of the scope. My only reason to go to inch would be to put some wider field eyepieces on the scope.

Andy Pyatt

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Re: Diagonal
« Reply #4 on: December 27, 2017, 09:50:04 am »
Great suggestion on the 2-inch and that would avoid the need for the adapter. Plus that price is awfully good. Is there any disadvantage to that particular diagonal?

George B Grimm

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Re: Diagonal
« Reply #5 on: December 27, 2017, 06:34:03 pm »
2in is the way to go. If you don't get the model with the sct screw on you will need the 2in visual back. 
Ignore my comments about the focal reducer. The diagonal wont be used with that.  When the time comes to image with a dslr just make sure to get a 2in adapter for that also, else vignetting. I never owned that screw on type of diagonal and the more I think about it I think it not be a good idea as my eyepiece would be so close to the rear of the scope I would bang my head. So you can choose from any other models and with the slip in type it could be used on a refractor also.

Ed McDonough

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Re: Diagonal
« Reply #6 on: December 28, 2017, 11:37:17 am »
Andy:
Here's the one that I use with my Nexstar Evolution 8. It should work with your LX 90. High Point sells it for $129.95:

https://www.highpointscientific.com/telescope-accessories/diagonals/celestron-2-diagonal-with-xlt-coatings-for-schmidt-cassegrain-telescopes-93527


Andy Pyatt

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Re: Diagonal
« Reply #7 on: December 28, 2017, 03:29:21 pm »
Hey guys, thanks for all your help and advice. Haven't decided yet so still thinking about it. I do want to be able to get some wider angle views so I think two in the way to go. Figure I need at least a 40 mm I piece as well and I don't think those work well in a one and a quarter.