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Prism dedicated to binos only or not?

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#1 ShaneOS

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Posted 16 August 2013 - 10:10 AM

I recently purchased the Baader Maxbright binoviewers. I also purchased a Baader T-2 prism diagonal with the intention of attaching the binos directly to the diagonal. I also have a couple of other 1.25" eyepieces. Should I leave the prism diagonal hooked up to the binos and use my standard 1.25" mirror diagonal that came with the scope (8" EdgeHD) when I use my other eyepieces? Or should I buy a 1.25" eyepiece holder to attach to the prism diagonal and use the prism all the time, bino and mono viewing?

2nd question: Will I ever need to buy a 2" diagonal or can I just use the prism diagonal? The prism diagonal is advertised as having a 34mm clear aperature. It seems like I read somewhere that the 8" EdgeHD is limited to 31-32mm due to the baffling anyway, so would I ever benefit from using an eyepiece with a field stop larger than 32mm-ish anyway? I may be mistaken on these numbers.

#2 Eddgie

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Posted 16 August 2013 - 10:37 PM

I have a Mark V and I just leave the Baader T2 Prism on the Binoviewer 100% of the time because is is just easier than unthreading the quick connector from the prism.

Just slip in your regular diagonal for normal use.

Also this. You can use even a 31mm Nagler with the EdgeHD 8" with great results. Don't be worried about using a 2" diagonal.

My advice though to everyone using an SCT is to always keep the back focus as short as possible. I recommend the Televue Short SCT to 2" adapter. This will work with the 2" nose attached to the front of the T2 Prism and this would allow you to easily swap from a 2" diagonal to the Binoviewer. The Short SCT adapter though will only allow a 2" diagonal with a short nose to fully seat (Televue makes a short diagonal, but I think there are some others).

The shorter you make the light path, the better.

#3 ShaneOS

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Posted 17 August 2013 - 09:17 PM

Thanks, I was thinking it would be a pain to unscrew the binos and screw on an eyepiece holder. I'll just get a 2" to 1.25" adapter and use my 1.25" mirror diagonal with my other eyepieces.

#4 ShaneOS

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Posted 18 August 2013 - 10:08 AM

I have the Televue Short SCT to 2" adapter. Which 2" to 1.25" adapter would be better, Baader 2" to 1.25" Pushfit Low Profile Reducer or Tele Vue 2" to 1.25" Eyepiece Adapter - Flat Top. It seems like they both have a short profile. It looks like the Baader has a lower profile, but I think I would have to modify the SCT to 2" adapter for the set screw. The Televue unit looks like it adds 9.5mm of light path as opposed to only a couple with the Baader. Any thoughts?

#5 Eddgie

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Posted 18 August 2013 - 01:45 PM

I would not kill myself over it (well, maybe I would.. I am pretty anal about this kind of thing).

Seriously though, a few millimeters won't matter. When it really matters is when you can reduce 30mm or 40mm, but avery little bit does help. Then it simplly becomse cost/value and each man or woman for themselves...






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