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Binomate binoviewer / 100mm f/6 achromat package

Posted by Tom Dove   08/26/2004 12:00AM

Two eyes are better than one; perhaps not twice as good, but enough better to make a binoviewer worthwhile. I'd discovered this last year at the Delmarva Stargazers No-Frills event when I looked through an AP binoviewer on one homebuilder's beautifully constructed Newtonian. It was an "Aha!" event, and I determined then to keep an open mind to opening both eyes.

My eyes are imperfect, with myopia and some astigmatism requiring corrective glasses, and a pretty good collection of floaters. I've had scopes only for a couple of years, but have discovered in that time that I can manage without the glasses if a particular eyepiece requires it, but will wear the specs whenever it's feasible. Binoviewing promised some relief from my own optical flaws, especially the floaters.

Still, it's hard to justify spending $600 or more just to find out if something is a good idea or not, especially when my scope collection doesn't even include anything that expensive. I have an Orion StarMax 127 Maksutov on an Astroview (EQ3) mount, an Orion StarBlast rich-field scope and a homebuilt 6" f/8 Dob, for which I ground the mirror but with mechanical parts from the Stargazer Steve kit. Only the StarMax seemed suitable for a binoviewer without some modification, and it's a long-focus scope unsuited for wide views.

Recent ads on Astromart by The Binoscope Company offered an irresistible combination: The Binomate binocular viewer ($299) plus a 100mm f/6 achromatic refractor, modified to accept the Binomate directly, for a total of $499. I'd wanted an achromat like that over a year ago and ordered a Burgess 1026 then, only to be disappointed by its non-delivery, so I exchanged a number of email queries and answers with Binoscope owner Joe Castoro and then sent him a check. Joe was very helpful and patient with my questions.

Within a week, the scope arrived by US Mail, well packed and in apparent good condition. It appears identical to the Orion 100mm f/6, only the tube is shorter, and I suspect that Joe is importing the unit from Synta in China; he doesn't say. It's silver and black, looking rather like a plumbing drain with a film developing tank stuck on the business end. It's functional but not beautiful, and I'll refinish it with Monokote to improve its acceptability in our home decor. My wife suggests that will happen very soon...

Since the Binomate hadn't arrived, I checked out the scope in Cyclops mode, using the top (non-optical) part of a TeleVue 3x teleconverter to add the necessary three inches of extra length before the eyepiece. It appeared to be out of collimation when tested with a Cheshire, so I loosened the objective's retaining ring, gently shook the assembly to let it settle onto its spacers, and retightened it just enough to stop it from rattling. The collimation was then easy to adjust until it was spot on. Shipping must have dislodged the objective. I mounted the scope on the EQ3, using the tripod screw in its base and a wooden block as a shim.

It's definitely an achromat, showing plenty of purple on leaves about 1/4 mile away on a hazy day, but quite usable on stars at night with images sharp right up to 120x (12mm Radian + 2x Orion Shorty Plus Barlow). I may get a Baader Fringe Killer for it just to clean up the view a bit more on bright stars, but the chromatic aberration is not noticeable on clusters, doubles and nebulae now unless I throw it out of focus -- and why would one do that?

Along came the Binomate itself, two days later. It was unscathed by the elephants of the USPS cancellation department and looked perfect in its fitted plastic case. It resembles my wife's Nikon 8x26 binoculars, and this compact size and light weight were two reasons, besides price, I was attracted to the unit. I hope to use it on my homebuilt Dob, where balance will be an issue.

I had bought a used 25mm Orion Sirius Plossl and a 10mm Antares Elite to add to those I had and make a starter set which would yield 24x and 60x with the achromat. I planned to use the 2x Shorty Plus Barlow to get four magnifications from the two eyepieces, but soon found that the Binomate refused to focus at all with the Barlow.

Joe had assured me that 25mm eyepieces would work satisfactorily in the Binomate, but Jim Gutman's Cloudy Nights review of the unit said they would vignette. If they did, I could sell one of the Sirius Plossls at no loss and buy a pair of 20mm Plossls, so it seemed worth the gamble.

The field stop is soft in the 25mm eyepieces, but the view seems quite usable to me and I can wear my glasses with this combination. I can only detect the edges of the prisms if light sneaks in past the rubber eye cups. The eye relief with the 10mm Elites is too short to use with glasses, but the view is wonderful if we don't count my own eyes' astigmatism. The field stop is sharp in the 10mm. I've had absolutely no trouble merging the left and right images or adjusting the interpupillary distance. There's a slight loss of brightness from the one-eyed view with both eyepiece sets but using both eyes seems to make up for that. The star images are as sharp through the Binomate as they are through the same eyepiece without it. Vertical collimation is right on, while there's a tiny bit of horizontal difference; it's not bothersome.

Summer skies in populated areas along the Chesapeake Bay are generally crummy, with plentiful haze. I live in a condo community on an island near the Eastern Shore and must contend with local streetlights and house lights in most directions, with good views only out over the water to the north through southeast and above about 30 degrees altitude. To see all the good stuff in the southern sky calls for a trip to a dark site such as Tuckahoe State Park, about 30 miles inland.

I immediately started enjoying the two-eyed view from my home, revisiting familiar places like the Ring Nebula and the double-double in Lyra (I couldn't quite resolve the closer pairs at 60x, but saw elongation and a hint of the division in one pair), and of course, the gorgeous colors of Albireo. The Dumbbell nebula was pleasant, although not as dramatic in shape as it is in the 6" Dob. The sparse open clusters in Cygnus even looked good, as did M103 in Cassiopeia. The nearby Owl (or ET) cluster was a delight.

Another evening, I put the Binomate onto the 5" Mak and explored the same areas with 61x and 154x. This scope has very good optics, and splitting close doubles at the higher magnifications is a snap.

The remarkable thing about binoviewing is how relaxing it is. After a session of one-eyed viewing, my eyes require a long time to return to their normal focusing; the non-dominant left eye remains disconcertingly blurred for an hour or more. With the Binomate, they're as relaxed after several hours of observing as they were at the outset, and floaters cease to be a problem. That's really nice, and I find myself spending many minutes on each object now, with the evening hours slipping by rapidly.

I'm quite pleased with the Binomate and see no immediate need to upgrade to something more expensive. Those who are accustomed to the high-end Denks, TeleVues or APs might find this unit marginal, but I'm happily ignorant of that better life and plan to stay so for a while. The problems now are obtaining higher magnifications with the 600 mm achromat and adapting the unit to my Dob. Since the Barlow does not seem to work, I'm casting about for a solution. Perhaps the Denk OCS is the best bet.

This combo will go to the Delmarva Stargazers' No-Frills Stargaze in September where a number of other astronomers can try it out. Check the Astromart binoviewer forum after that for any updated opinions.

-- Tom Dove