can I use a binoviewer with my reflectors?
Posted 16 October 2013 - 02:12 PM
I was reading about the Celestron Stereo binocular viewer from Amazom. It says it doesn't work well with reflectors, only refractors and SCTs. Why is this?
Posted 16 October 2013 - 02:42 PM
Worth doing in the 8" Dob. The views of the moon are excellent!
Posted 16 October 2013 - 04:29 PM
Posted 16 October 2013 - 04:38 PM
The reason is that the light has to travel about 110mm inside the binoviewer before it gets to the field stop of the eyepiece.
There really isn't a Newt or Dob made that will allow you to rack in the focuser 4.5" so this is why a regular binoviewer won't work.
The 1.6 GPC that comes with these is really there for refractors because most refractors have a lot more focuser travel, and the 1.6 barlow often (but not always) gives just enough light path savings to allow many refractor to reach focus.
There are three things you can do.
The first is to modify the telescope by moving the mirror forward about 4 inches, but then you also need to make the secondary mirror a bit bigger so the light cone does not miss the outside edge.
Second option is to go to a Denkmeier system This uses an OCS that goes inside the focuser system but you can also get a powerswitch that allows you to change magnification easily.
When you factor in that you can do most of your observing with a single pair of eyepieces (rather than buy multiple pairs) the value proposition is actually very good.
The last option is the Baader Maxbright, Televue Binovue, or Mark V, used with the Baader 1.7x GPC which is also a coma corrector. The Maxbright is a fraction of the cost of the Mark V and half the cost of the televue, but it only works with shorter focal length widefield eyepieces like the 19mm Pans or the 20mm ES eyepeices.
This is why the Denkmeier system is a pretty good value. You can get low, medium, and high powers with one pair of eyepeices, and while the costs seems high, it really isn't that bad vs buying the Maxbright with a 1.7GPC and you get lower powers too.
Posted 16 October 2013 - 09:02 PM
Of course, a Baader Mark V or Denkmeier Binotron would be very nice with a reflector. I'm thinking about getting one of those two myself. But it's not necessary.
Posted 16 October 2013 - 10:59 PM
Posted 17 October 2013 - 08:31 AM
Tried and tried, but gave up.
Maybe they would be OK with small apeture binos, but simply unusable with the Mark V and 24mm ES eyepeices.
Posted 17 October 2013 - 08:42 AM
Posted 22 October 2013 - 05:18 PM