Fan Of The Couch Potato Chair
Posted 07 August 2005 - 01:10 AM
I'm comparing it with a UA Unistar (not a parallelogram mount) on a bogen 2046, an older style parallelogram mount on an old Celestron photo tripod, and a SkyWindow mirror mount on the Celestron photo tripod. The primary binoculars I've been using are Obie 15x70s, and a surplus pair of IDF Fuji Meibo 14x70s on the various mounts. I use a Canon 15x45 IS for hand held.
For comfort, the CPC is the big winner, with the SkyWindow a clear second, and the other mounting systems far behind. The Unistar and parallogram mounts are not useable in a chair. I've read that a UA parallogram mount is useable from a chair, but I haven't tried one. I use the SkyWindow seated, but I have to pick up my observing chair and moving it regularly and shift my posture to observe comfortably while scanning; I'd expect this to be the same for a pgram mount used from a chair. While I've gotten used to mirror reversed finding and hopping, this is a minus, particularly when using star charts. The CPC is easy because you can look where you want to point and bring the binoculars to your eyes. Scanning is any direction is easy, and you remain comfortable while doing it. I find pointing more difficult with either of the other two "standing" mounts. The combination of having to hold a less than comfortable neck position while adjusting these mounts is quite tiring by comparison to the CPC.
The SkyWindow has some problems that are unique. First is image quality (mostly astigmatism) at 15x. I tried their higher quality gold mirror, but the mirror I purchased on Astromart was at least as good as the new gold sample mirror I tested. (thanks Brockenroller). It doesn't bother some folks and it drives others away from the SkyWindow immediately. I guess I am somewhere in between since I notice it and it bothers me on brighter stars, but it was not an immediate show stopper. There is also a noticeable loss of brightness due to the mirror, and the mirror dews very quickly when the conditions are right. Since all the other mounts let you view straight through the binoculars, the optical quality and dewing issues are simply those associated with the binoculars.
Of these mounts, the SkyWindow was the steadiest, followed by the Unistar and CPC, with the parallogram dead last. Frankly I think this speaks more to the quality of my pgram/tripod combination than to pgram mounts in general. The CPC actually has a better damping time after moving the binoculars than either the UA or pgram, but it does have a "heart beat" problem as noted in the review here on CN. I only found this to be a problem when trying to split close doubles, and it became less noticeable when I was viewing wider fields. At least in my case, this could be significantly reduced by viewing from slightly behind the binoculars and avoiding the mechancial coupling of the oculars to my eye sockets. The CN reviewer also mentioned using foam pipe insulation to decrease the coupling between the observing chair and the rotating platform. I have not tried this yet.
In terms of setup and transport, none of these systems are too bad. The CPC is definitely the bulkiest single piece, but it is thin enough when folded to fit conveniently on the floor between the front and back seats of my car. The UA mount is the quickest to setup, followed by the CPC, then the pgram and finally the SkyWindow. This is because I store the SkyWindow in a case and need to do some assembly before mounting it on the tripod, and mounting the binoculars.
All in all, the CPC is currently my favorite mounting system for 15x binoculars. It is not rock steady, but it is so comfortable and easy to use, that it more than compensates. I recommend it highly.
Posted 08 August 2005 - 02:52 AM
If you aren't familiar with the CPT, here is Sim's bare-bones website:
And here's a Cloudy Nights review:
I got into this big binoculars thing backwards -- I bought the mount first. I was at last year's Nebraska Star Party and saw an old guy in the vendors' area demonstrating this interesting gadget -- its basically a lazy susan platform for a beach chair, and an A-frame of PCV and aluminum pipes to mount the binoculars. Its inventor, Sim Picheloup of Houston Texas -- "the Stargeezer" -- was demonstrating it during the daytime with 10X50 binoculars.
At that point I had been into amateur astronomy for about 10 years, and owned an 8" dob. But I have found that often when my telescope was set up I preferred to sit back in beach chair with my 10X50 binos (Minolta Standard EZ) scanning the Milky Way. But I just couldn't hold them very steady without the stars dancing around even when I was braced against whatever was handy. I had been half-heartedly thinking about getting P-mount for some time. As soon as I tried the CPT I could see that it would be great for this purpose, and bought one then and there. It cost $300, complete with a good-quality beach chair. For the rest of the star party, under incredibly dark Western Nebraska skies, I mostly used by binos instead of the dob.
It held the 10X50s rock steady. You adjust alzimuth by swivilling the chair around with your feet. The friction-fittings on the mount allow for easy adjustment of altitude. As the altitude gets higher, you can recline the beach chair to lean back. Looking at zenith is no problem at all -- the beach chair goes to nearly horizontal, and the mount's friction fittings allow the A-frame to adjust to wherever the binos are needed but still take their weight. Sim even added a head-rest to the beach chair. The CPT does not look like a slick Orion or Celestron product. Sim's design approach is more "form follows function". It looks exactly like what it is -- a home-made gadget assembled from birch plywood and common hardware store parts. (I understand that Sim doesn't even have a workshop. He makes them in his apartment.)
It was only after I bought it that I realized that the CPT had really been designed for use with larger binos. I hadn't given the idea of getting big binoculars a second thought before that. That's when I began lurking in this Forum. Sim had said that it could hold up to 10 lbs. Last year, that generally meant up to 20X80 or 90. He admitted that at that weight/magnification some people were bothered by vibrations caused by their own heartbeat, but other people did not find this bothersome. Also, he had recently made an improvement to the design (adding a sheet of stiff plastic to the base to stiffen it) which helped with this problem, and I had the newer model.
While lurking and researching I had developed a serious case of aperture fever. When Oberwerk announced their new 25X100 IF in October I ordered one of the first units. 10 lbs exactly! As winter progressed and I continued to lurk (as well as use my new big binos) I developed a case of "quality fever" and longed for a wider field. A few months ago I bought a Fujinon 16X70 FMT SX. So now I have experience using both of these binos on the CPT, as well as my simple 10X50s. It works very well for all of them! I can see a bit of my heartbeat in the 25X100s, but its still a lot less shaky than when I hand hold and brace my 10X50s. For me, it doesn't detract from the viewing experience, especially when you are scanning around -- and scanning around is something that the CPT does very well. However, as is mentioned in Vincent Bert's above-cited review, the mount is definitely affected by wind -- its not really very useable when its breezy.
The CPT collapses down for storage and moving. It takes only a few minutes to assemble or dissassemble (even in the dark), and all of the parts stay attached so they can't get lost. When its collapsed, the CPT is quite portable -- not very heavy, but a bit awkward. I live across the street from a park that has a great southern view from a hilltop. I can carry the CPT and beach chair, with my 25X100 in its case in a backpack along with charts and other viewing paraphenalia, to the hilltop in one trip. Its about 500 metres. But I wouldn't want to carry the load much further than that.
After reading the various discussions about solving design problems for bino chairs I have came to appreciate how well thought-out Sim's design really is. For example, the binoculars are suspended from a "U" in the crossbar, so their centre of gravity is in line with the crossbar. This way, the friction fittings on the crossbar do not need to be particularly tight to keep them from slumping. There are six friction fittings in all. They are adjustable, by tightning hoseclamps with a screwdriver. Obviously, the ones on the legs of the A-frame need to be tighter to take the 10# weight of the 25X100 than for my 10X50s. But one setting seems to work for both (although its tighter than it needs to be for the small ones).
Besides selling assembled CPTs, Sim sells the plans for $15. I got a set of plans with my already-assembled unit. They are well-illustrated and appear to have clear and complete step-by-step instructions. Sim also sells three versions of parts kits, with varying degrees of pre-assembly.
I highly recommend the CPT mount! This summer I only set up my dob on one night, but I've been viewing with my binoculars on just about every clear evening. Now, I think that leaning back in a comfortable chair is the only way to view the stars and fuzzies.
Posted 08 August 2005 - 06:26 AM
Posted 08 August 2005 - 09:03 AM
Thanks for the detailed review.
Posted 08 August 2005 - 10:17 AM
I have considered using closed-cell foam as a damper. I could either attach strips to the platform, or get a tube of that insulation they use for hot water pipes. So far, I haven't bothered. The problem is that minor.
A project that I'm more likely to do sooner is to improve the CRT's portability by buying a used backpack frame and rigging it so that I can carry the platform unit and bino case (and maybe the beach chair) on my back. Their combined weight is no problem -- as I said, the platform is more awkward to carry than heavy. The trick would be figuring out a system for securing the items to the frame that is both stable and easy to do in the dark.
Posted 08 August 2005 - 10:22 AM
Though Sim built my chair, it came with the instructions for building it, which are also handy for repair and maintenance. The instructions are a cross between a model airplane instruction set, a scavenger hunt list and a Rube Goldberg cartoon. Every piece and element (string, glue, etc.) is pictured, named and numbered for the later steps. There are also suggestions on where to find the parts, and in a few cases work arounds if you can't find a particular part. I mean no disrespect to Sim, since the product and the instructions are a tribute to his ingenuity. IMO, the instructions, parts kits, and assembled chair are all bargains.