Posted 08 May 2008 - 11:12 AM
Since somebody asked, the Fujinon 7x50 is no great shakes in this department. The field is rather curved, about 2 diopters from center to edge. Despite it's narrower apparent field, the edge is quite a bit softer than the 10x50.
Henry Link has reported in other forums that the optical train of the Prostar (and its 10x70 sibling) and FMT are very similar except the Prostar has an extra convex lens cemented to the output end of the prisms. Very interesting! Comments, BillC or Henry?
While the Prostar is apparently supreme for edge correction, it's apparent field is only 53 degrees. Several of the second-place binos provide 60-67 degrees. If these were field-stopped to 53 degrees, Ed, would it be a different story?
Posted 08 May 2008 - 11:29 AM
The only one I can remember with a separate field-flattener was the old Swift Commodore. This was a good bino--for the money--but Swift's lack of ability to really promote it killed it off.
Posted 08 May 2008 - 11:52 AM
The Nikon 7x50 ProStar has a 383 foot true field at 1000 yards.
It would be interesting to see how sharp the Zeiss is at the true field of the Nikon.
Posted 08 May 2008 - 12:10 PM
The Prostar 7x50 also has the widest Tfov of all 7x50s tested. It's not until you get into 8x binoculars that you start seeing wider Afov eyepieces and Tfov wider than 7.0Â° to 7.5Â°. But even with that, in fact only 3 out of 11 of the 8x binoculars that I've measured have a wider Tfov than the Prostar 7x50.
FWIW, I just checked my data files. 19 out of 36 small binoculars tested have Afov 54Â° or smaller. 14 of them have a narrower Afov than the Prostar. Prostar is just about right in the middle of Afov and is near the top in Tfov of 36 different binoculars tested.
So as it turns out, in the grand scheme of things, the Prostar Afov of 53Â° is NOT really all that narrow compared to many other binoculars ranging from 7x to 12x, and as far as comparison to 7x and 8x binoculars, it has a wider Tfov than 3/4ths of all 7s or 8s I've measured.
Posted 08 May 2008 - 12:24 PM
It would be interesting to set out two small lights separated by 383 feet and get back 1000 yards to see how sharp they are in the Zeiss.
Posted 08 May 2008 - 12:32 PM
take the closest observable double star pair that can be seen at the edge of the Prostar and try to observe it in the other binocs. Starting with the double placed on the extreme edge, slowly move it inward until it can be seen and record the position. Try Alya, theta Serpens; an even magnitude 22" pair. I saw theta Serpens all the way out at 90%+ of fov in the Prostar.
FWIW, there are some 8x binoculars I've tested in which I cannot even see theta Serpens beyond dead center.
Posted 08 May 2008 - 12:37 PM
A few years ago I won a perfect Prostar on auction at a very fair price. I took my time comparing it to my Fujinon Meibo for Terrestrial (yes) viewing. I sold the Prostar and kept the Meibo.
The Prostar felt somewhat tunnel-view , the Fujinon felt natural. The Prostar was especially clunky to hold steady, the Fujinon (rubber armored), easier to hold steady--though still a big, heavy 7x50.
So despite the technical, optical excellence of the Prostar, I was seeing and enjoying more, Terrestrially, with the Fujinon.
Of course this is off topic regarding Nagler, but yet another reminder that bino "better" and "best" are not absolute, but relative to for-what and to-whom.
Posted 08 May 2008 - 12:39 PM
Advertised TFOV: Prostar 7.3, Fujinon 7.5.
Actual measured TFOV: Prostar 7.5
Posted 08 May 2008 - 12:41 PM
Notice that it's placed in front of the objective focal plane and does not move with the eyepiece elements, so I think it should be considered a third objective element. My guess is that it's designed to correct field curvature by making the field curvatures of the objective and the eyepiece nearly complimentary. I agree with Ron that other so called "field flatteners" (Fujinon FMT-SX, Nikon SE, Pentax PIF) appear to correct astigmatism, but not field curvature.
Posted 08 May 2008 - 01:26 PM
I agree with Ron that other so called "field flatteners" (Fujinon FMT-SX, Nikon SE, Pentax PIF) appear to correct astigmatism, but not field curvature.
Seems to agree with what I've found. Examples:
Fujinon FMT-SX 10x50, all or nearly all of the outer field aberration is field curvature.
Nikon SE 10x42, approx 80% of all outer field aberration is due to field curvature.
Nikon SE 12x50, approx 75% of all outer field aberration is due to field curvature.
Note, these binoculars outer filed total aberration is very well controlled, it's just being pointed out here how much of what is there is due to curvature.
Nikon Prostar 7x50, close to zero.
Posted 08 May 2008 - 04:36 PM
Posted 08 May 2008 - 05:11 PM
Posted 08 May 2008 - 06:00 PM
Posted 08 May 2008 - 06:41 PM
The term "Nagler-like" generally means a WIDE AFOV in additon to edge sharpness. Most OEMs consider their binos to be WIDE if the AFOV > 65Â°. So I am suprised no one has mention the Nikon 8x30 E2 with its 70Â° AFOV (8.8Â° TFOV). Generally still available in most of the world ex USA for some silly reason.
I have data on over 60 different binoculars in my database. A wide variety from 7x35 to 25x100, and many many small sizes and large sizes in between.
Less than 10 binoculars have Afov of 65Â°. I would say a 65Â°+ Afov is quite uncommon in binoculars. Only 4 of them handle the wide field well, so less than 7% of 60 binoculars have a GOOD wide field 65Â° or larger.
There are just as many in the data that have 50Â° or less as there are that are 65Â° or greater.
Half of all binoculars range from 60Â° to 65Â°
More than 20 binoculars have Afov of 53Â° or less. We sometimes hear people describe this as tunnel like, yet more than 1/3 of binoculars have eyepieces with these narrow field stops. Only 3 of these handle outer Afov sharpness poorly.
More than 15 binoculars have Afov of 64Â° or greater. Of these, 10 handle outer Afov sharpness poorly.
Posted 08 May 2008 - 09:05 PM
Posted 09 May 2008 - 10:34 AM
Posted 09 May 2008 - 03:13 PM
And #'s 2 & 3 would be??
Sorry- I also meant to add the WO 7x50 into the mix as well... as EdZ noted in a different thread- on the Resolux 10x50's-
The WO 7050:
has the finest resolution of any small binocular I've tested, so far. ...has the greatest illumance of any small binocular I've tested so far.
There seems to be enough top quality binoculars, and close enough in many aspects that to just place arbitrary numbers on them without the comments to go along with them is selling them short. It'd be nice, when looking at the upper end binoculars in any given class, what the differences are before making a purchasing decision. I, for one, live where the best bino's I can walk into a store and compare are in the $100-$200 range. Top quality bino's? I have to take a shot in the dark based upon what tests and reviews I can find- mail order them and hope for the best. And if one reads a review from one source- and then later another one from another source, by someone else, it's still not really as accurate a comparison as if the same person reviews them all at the same time and under the same conditions. EdZ has been exceptionally invaluable to us all here (Thank You, EdZ! ) in providing computer-like accurate and meaningful comparisons and tests. Would simply love to see him do a shoot-out between the top, say- 7x50's (as they seem to be a particular hot topic of interest at the present time) then, perhaps 10x50's, etc.
Posted 09 May 2008 - 04:48 PM
Posted 09 May 2008 - 06:05 PM
Posted 09 May 2008 - 07:26 PM
EdZ, as a new owner of a Fujinon FMT-SX 7x50, I am looking forward to your test results.
EdZ wrote Small Binocular Series - the 7x50s is underway.
Posted 09 May 2008 - 07:39 PM
Wes James wrote: I, for one, live where the best bino's I can walk into a store and compare are in the $100-$200 range. Top quality bino's? I have to take a shot in the dark based upon what tests and reviews I can find- mail order them and hope for the best. And if one reads a review from one source- and then later another one from another source, by someone else, it's still not really as accurate a comparison as if the same person reviews them all at the same time and under the same conditions. EdZ has been exceptionally invaluable to us all here (Thank You, EdZ! ) in providing computer-like accurate and meaningful comparisons and tests. Would simply love to see him do a shoot-out between the top, say- 7x50's (as they seem to be a particular hot topic of interest at the present time)
I agree, EdZ's test are the best comparisons going.
then, perhaps 10x50's
I would like to see the Pentax DCF ED 10x50 added to one of EdZ's exhaustive tests.
Posted 09 May 2008 - 07:44 PM
BillC wrote:Prostar #1
FMT #4 (#2)
Orion #5 (#3)
Bill, of course, we look forward to your supporting documentation for the above ratings.