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chgomonitor
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Reged: 09/18/08
Posts: 90
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I read the rather amazing widefield specs for these in a state of minor amazement. Given their price, I kept my expectations to a minimum. When I saw a 10 dollar price tag at Adorama I ordered a pair.
These are advertised as having 12.5 degree TFOV, pretty impressive. Initially I was shocked when I looked through them and saw a field of view of about 4 degrees.
Eventually, I discovered by moving my head from side to side and peering through the edges of the field I probably could see 10 degrees of width, or more - but not at any one time.
The clue, of course, is the apparent field of view, which calculates out to something under 50 degrees, pretty "straw tube" hole-like, LOL. To say the least, the width of the available field is less than awe inspiring.
The rubber eye tube caps when forced will fold down to some degree, but even then you can't get your eyes close enough to see the wider field, it's just not there unless you shift your view from side to side.
These have no diopter adjustment and don't really offer enough center focus depth to adjust for my bad left eye without my glasses on. With my glasses on they are almost acceptable focus wise, but are just a tad short on eye relief to make this enjoyable.
In terms of night viewing they do add about a single magnitude to my light polluted skies. Field of view is fairly sharp across the center field to it's edges, but that's because you aren't seeing the entire field at any given time. Look all the way horizontally to the real extreme edges and it's quite a mess sharpness wise. Contrast and field brightness are both remarkably poor.
Flimsy focuser easily pushes inwards by accident and has some backlash. Cheap metal frame and limited rubber armor. Not sure if these are really glass lenses and I don't see much in the way of coatings. The objectives are well recessed, which I like.
IPD adjustment is huge. They have to be fully folded to fit in the carry case. Neck strap is nylon string. IPD adjustment greatly impacts TFOV, keep them as wide as you can while in use.
There is no tripod adapter. They are incredibly light. Mechanically and optically these border on being toys or total junk.
I was going to send them back or give them to kid (which I still might do but I hate inflicting junk on kids), but then I discovered them slightly handy for satellite spotting, I'll probably keep them. Good for a laugh if nothing else.
Far from my solution for my gigantic apparent field of view quest, the search continues. I guess you get what you pay for, LOL.
Happy Sky Scanning! - Ted
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hallelujah
Carpal Tunnel
   
Reged: 07/14/06
Posts: 2144
Loc: Rocky Mt. High Colorado
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Quote:
Good for a laugh if nothing else.
I guess you get what you pay for, LOL.
Happy Sky Scanning! - Ted
How about one of these? Minox Macroscope MS 8x25
http://www.minox.com/index.php?id=1569&L=1
http://www.amazon.com/gp/product/B000K2D7H6
-------------------- Celestron Traveler 8x25 & B. & H. 8x40 FC JAPAN & Revue 10x50 CF Porro FC JAPAN &
Pentax 12x50 PCF WP II FMC & Pentax 16x60 PCF WP FMC &
Pentax 20x60 PCF WP II FMC & Orion 12x63 Mini Giant FMC JAPAN &
SPECTRUM I 20x65 FC JAPAN &
Orion 15x70 Little Giant II FMC JAPAN & Orion 20x70 Little Giant II FMC JAPAN
Orion 16x80 Giant FMC JAPAN & Orion 30x80 MEGAView FMC JAPAN
Barska 30x80 X-Trail LW FC & Burgess Optical Series II 20x90 FMC
Hallelujah! For the LORD God Omnipotent Reigneth
Edited by hallelujah (12/03/08 09:51 AM)
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KennyJ
   
Reged: 04/27/03
Posts: 12879
Loc: Lancashire UK
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Thanks again Ted for another useful potential future reference .
Kenny
-------------------- If everyone is thinking the same thing , no-one is thinking - General George S.Patton
Zeiss 7 x 42 BGAT
Captain's Helmsman 7 x 50
Nikon 10 x 42 Superior E
Swift Audubon Kestrel 10 x 50
Helios 15 x 70 Observation
Strathspey 20 x 90
Televue 76 APO
Zeiss 85 Diascope
Helios 102 f5 refractor
Various eyepieces barlows tripods mounts etc.
Panasonic Lumix DMC - TZ5 digital camera
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GlennLeDrew
Pooh-Bah
   
Reged: 06/18/08
Posts: 1250
Loc: Ottawa, Ontario, Canada
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Several years ago Bushnell offered a 4x21 in its Xtra-Wide line-up (in addition to the 7x32 and 10x50). It had a (real) true field of 17 degrees, but of course only about the inner 1/2 was acceptably sharp. Even so, the on-axis quality was quite good.
They were of fixed-focus design, which I got around by 'breaking' the small glue blob which locked the eyepieces in place. An interesting feature was the ability to laterally translate the eyepiece--kind of like the eccentric adjustments on the objectives of some other binos--to achieve collimation, which of course was set once the eyepieces were glued at the factory.
After some time using them I took them apart, with the intention of making them into a right-angle instrument via the use of Amici prisms. By the way, instead of prisms, the light path was folded by a system of mirrors, which did result in a bit more light loss because of the use of 'standard' reflectance coatings.
I still have the optics, and may one day get around to making a simple RA bino with them...
-------------------- Home-made 11X50 right angle bino, 8.1 deg. FOV
Modified 26X100 bino, 3.5 deg. FOV
Home-made Mk II RA bino, using interchangeable objectives and eyepieces
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Mediocre minds discuss people. Good minds discuss events. Great minds discuss ideas.
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