Last updated: 7 June 2005
Burgess Optical Binoviewer from High Point Scientific www.highpointscientific.com
Cost $199.00. Includes 2 - 17mmWA eyepieces.
BaK4 Prisms, Broadband Optical
Coatings, Individual helical eyepiece focusers,
nosepiece is threaded for standard 1.25" filters, 3 nylon eyepiece set screws per eyepiece allows better eyepiece alignment at higher powers. 2 free 17 mm wide angle eyepieces. Unit with eyepieces weighs 25.5 oz. (1 lb., 9.5 oz.).
The Binoviewer (Fig. 1) has a well-built solid feel to it. The eyepieces attach easily with the nylon set screws and can be individually focused. The unit rotates to fit your eye separation smoothly and stays put. It is one heavy dude and you will need a counterweight system for balance if you are going to use the Go To and tracking function on your ETX. An option is to slew to your target without the Binoviewer then insert it into the eyepiece holder as not to put strain on the motors when slewing. This would be advisable for both alt/az and polar modes.
I have an ETX-70, 125 and an 8” Dob. The unit is designed as is to focus with the Mak/Cass design scope but not with a refractor or reflector. To achieve focus with these scopes you need to purchase the optional Burgess 1.5x relay lens ($29) or use a Barlow attached to the front on the Binoviewer (Fig. 2). I use a 2x Barlow and the unit reaches focus on both the refractor and reflector without a problem. High Point recommends a 2x shorty. Using the Barlows adds more weight but gives one advantage. The Binoviewer without the Barlow will not fit squarely into the OTA eyepiece holder of the ETX-125 without hitting the finder scope. To overcome this you must either turn the Binoviewer at an angle (Fig. 3) to clear the finder or use a Scoptronix eyepiece extender (Figs. 4 & 5) to give it more height. The optional Burgess 1.5x relay lens is a little thicker than a 1.25 color filter. This solves the extra weight problem, but not the clearance issue. This is not an issue with a Dob or the ETX-70 (Figs. 6 & 7).
The optics on the 17 mm eyepieces are very good and sharp, especially when they are free. You can purchase other wide angle eyepieces from their website. I have never used the other more expensive binoviewers ($5-700.00), so I can give no comparison to the optics. If you are like me and have several identical oculars from special deals or multiple scope purchases then you won’t need additional eyepieces. It does take getting use to looking through two eyepieces and merging the images, but it is more comfortable. You never notice how much you squint and the muscles you use in your face using a single lens until you use a binoviewer.
I was very impressed with the views of the moon and planets. It has a 3-D effect on large bright objects. I have not tried it yet on star clusters or nebulae. This is a novelty purchase and certainly not a necessary piece of equipment. But for the money it is an easy, relax full view of our universe.
Fig. 1 Fig. 2 Fig. 3
Fig. 4 Fig. 5 Fig. 6
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