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ronharper
Carpal Tunnel


Reged: 02/14/06
Posts: 2065
Fujinon FMT 50mm: 7x SX vs 10x SX2
      #1164216 - 09/25/06 02:53 AM

After using a 7x50 Fujinon FMT-SX heavily day and night for a few months, I came around to the usual point of view that for astronomy in my 5.5mag backyard, I'd be better off with a 10x50. I was ready to get a Garrett Grizzly, when a FMT-SX2 came along for a good price, and I bought that instead. I've done a careful, though not very quantitative, comparison of the two, which I'd like to share here, for you Fujiphiles out there.

Many differences between the views can be attributed to the difference in magnification, as opposed to quality differences. The 7x is the better daytime glass, due to the large exit pupils which give a quicker view and have no blackout issues around sunset when the eye's pupil enlarges through the 5mm region. The wide true field makes getting onto a moving bird easy, while the narrow apparent field is easy to view right to the edge. The curved field and absence of astigmatism or coma, combined with the large depth of focus at 7x, combine to make focussing, intrinsically difficult with the individually adjusting eyepieces, rarely necessary. 7x is easy to hold even when I am somewhat exerted, even useful looking out the window of a moving car. Long views across warm near-desert terrain here in New Mexico are usually so messed up by mirage that 7x shows about all there is to see. Conversely, the 10x is the night-sky winner. I'm looking up, and calm or braced, and the land is relatively cool, so that holding and seeing are not important issues. The additional effective aperture and extra magnification combine to make virtually every object in the sky more visible, beautiful, and dramatic. These behaviors are well-understood.

Now I come to the more subtle differences that are the real subject of the review.

Appearance: The 7x is the original version, black and straight profiled. The 10x, though labeled SX, not SX2, is clearly of the more recent design, having the fatter, rounded shape and the rubber covers on the rear of the prism housings. It is, however, all black, not the grey shown on websites advertising the SX2.

Handling: The old-style conical barrels of the 7x come to a slimmer entrance to the front of the prism housings, where I grab ahold of them, and so are easier to hang on to, while the fat style of the 10x feels like a handful. I can't feel any difference in the weights.

Field of view and eye relief: The 7x measures 7.3 degrees, vs 7.5 labeled, with plenty of eye relief to see the field stop without or with glasses, with the deformable rubber eyecups being up or down as needed. Although the apparent field of the 10x is considerably larger, I cannot easily see the field stop, and with or without glasses I only realize 6.0 degrees of the advertised 6.5 degree true field. Both binos require a snug fit against the head which steadies the view, with no need to hold away from the face to avoid blackout.

Color error: Under harsh black-on-white conditions, neither shows color on axis. Off axis, both show moderate lateral color, but the 10x shows less at the same apparent field angle.

Field sharpness: On axis, both are as sharp as my practiced vision can see by day. At night, the 7x shows slight flaring on Jupiter, while the 10x is completely clean, which probably says as much about my eyes as about bino quality. Off axis, my lack of focus accomodation limits my perceived sharpness of a curved field compared to younger or more fortunate older observers. By day, the 10x is noticeably better, but the 7x isn't bad at all. A blurred stump still looks very much like a stump, after all. At night it's a different story, because a blurred star hardly resembles a star. Here, the 10x shines compared to the 7x. The small degree of blur noticed halfway to the edge in the 7x is not realized in the 10x until fully 75% of the way, and this in a larger apparent field. Coupled with the difficulty of observing the edge of the wide apparent field in the 10x, the result is that I notice blurred stars in the outfield of the 7x, while in the 10x I do not. Often, a star group whose edges look blurred in the 7x will look all-sharp in the 10x, despite the greater magnification and apparent field! The 7x eyepieces are said to have 5 elements, while the 10x has 6, which may be responsible for this difference, and partly responsible for the large price difference (about $440 street for the 7x vs $650 for the 10x).

Coatings: Perhaps my 7x is an early version, but the coatings reflect, though rather dimly, a simple green color. I always thought, what a bad color to reflect away--the eye's favorite! The 10x coatings are clearly more advanced, with reflections that are considerably dimmer, and tend to blues and purples on the objectives and brownish reds on the eyepieces. They appear to be equal to those on a friend's Nikon SE. Due to a clumsy accident, I learned that the old coatings are about as tough as, if not tougher than, glass itself. Whew! May I never repeat that experiment.

Accesories: The newer 10x comes with a much nicer, stiff, supportive, and padded synthetic case than the old 7x's clunky hard leather box. The eyepiece cover for the 10x is a completely satisfactory well-fitting two-cups-on-a-flexible-connector, vs the useless loose oblong box of the old. The new strap is a neat black padded one that discreetly state the brand, vs the excessively large and bright yellow lettered old style. My 10x has the optional captive objective caps, which may be unsightly to the onlooker, but fit well, are easy to work, and stay out of the way during use. I recommend them.

Night sky observations with the 10x, impossible with 7x, elbows braced:
M57 seen as definitely a fuzzy patch.
Alberio cleanly separated out to 3/4 of the way to the edge of the field, repeated high, low, left, and right in the field.

I wouldn't part with the 7x. It is the better all-round glass, and if I could have only one, it would be my choice, as it is better by night than the 10x by day. But at night, it is simply no contest--the 10x is a very impressive bino for astronomy.

Ron


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cota_scope
sage


Reged: 05/16/04
Posts: 357
Loc: sioux city ia
Re: Fujinon FMT 50mm: 7x SX vs 10x SX2 new [Re: ronharper]
      #1164462 - 09/25/06 10:00 AM

ron very good review.i also have a pair of the fujinon 10x50s and agree with you, one of the best 10 power binoculars i ever looked threw. also see this review http://www.holgermerlitz.de/fujinon10x50.html regards john

Edited by cota_scope (09/25/06 01:32 PM)


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Rich V.
Post Laureate


Reged: 01/02/05
Posts: 3143
Loc: Lake Tahoe area, Nevada, USA
Re: Fujinon FMT 50mm: 7x SX vs 10x SX2 new [Re: ronharper]
      #1164623 - 09/25/06 11:44 AM

Nice review, Ron,

Though I'm not a big fan of 7x50s, I've very much wanted to try the 10x50 Fujis. My current 10x50s are acceptable but the FOV is too narrow for my liking.

When the 10x50FMTs came out, I figured they would share a lot of qualities with the 16x70s which I enjoy a lot. You seem to have confirmed this for me!

You mention that you can only see 6 of the 6.5 FOV, though. Does this mean that the eye relief is so short you can't get your eye close enough to the eyelens to see the field stop? With the 16x model, I need the eyecups rolled back to see the field stop, even without eyeglasses.

Just wondering if the 10x model is lacking eye relief also. The specs say it has 7mm more than the 16x so I would not expect ER to be a problem. If not, what's going on here?

Thanks for the report,

Rich V

--------------------
Binoculars:
33/50/71/150x100 Saturn III, 22x70ED, 16x70 FMT-SX, 10x50 PCF-V, 10x43 DCF-SP, 10x35 EII, 7x35 E, 8x30 EII,
7x26 Custom, 8x23CF AS Diplomat, 6.5x21 Papilio
Scopes:
C9.25, TMB130SS, SV80S-LOMO 80/480
IDA member


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KennyJ
The British Flash


Reged: 04/27/03
Posts: 20139
Loc: Lancashire UK
Re: Fujinon FMT 50mm: 7x SX vs 10x SX2 new [Re: cota_scope]
      #1164630 - 09/25/06 11:47 AM

Ron ,

Many thanks for a very rare comparitive review !

You mentioned some very interesting points .

Clear skies , Kenny

--------------------


Milton Wilcox R.I.P






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Mark9473
Postmaster


Reged: 07/21/05
Posts: 6459
Loc: 51N 4E
Re: Fujinon FMT 50mm: 7x SX vs 10x SX2 new [Re: KennyJ]
      #1164910 - 09/25/06 02:26 PM

very impressive and informative review, Ron!

--------------------
Mark
Leica 8x20; Nikon 7x35; Vixen 8x42; Orion 15x63; Docter 15x60
WO Megrez II 80 FD / APM 107mm f/6.5 / Mewlon 210 on DM-6 + Berlebach Planet


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btschumy
Vendor - Southern Stars


Reged: 04/13/04
Posts: 1708
Loc: Longmont, CO, USA
Re: Fujinon FMT 50mm: 7x SX vs 10x SX2 new [Re: ronharper]
      #1165121 - 09/25/06 04:18 PM

Quote:

Although the apparent field of the 10x is considerably larger, I cannot easily see the field stop, and with or without glasses I only realize 6.0 degrees of the advertised 6.5 degree true field.




The Fuji 10x50s are spec'ed at 20mm of eye relief. If this is true, I'm surprised you cannot see the entire field stop even without glasses. Care to comment more on this?

--------------------
Bill Tschumy
Southern Stars


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Rick
Post Laureate


Reged: 04/12/05
Posts: 3285
Loc: Tokyo, Japan
Re: Fujinon FMT 50mm: 7x SX vs 10x SX2 new [Re: btschumy]
      #1165146 - 09/25/06 04:33 PM

I know the Fujinon literature says 6.5 but doesn't the printing on the housing say 6.3?

-Rick


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patter1
professor emeritus


Reged: 01/19/05
Posts: 597
Loc: Canada
Re: Fujinon FMT 50mm: 7x SX vs 10x SX2 new [Re: Rick]
      #1165154 - 09/25/06 04:39 PM

>>>The Fuji 10x50s are spec'ed at 20mm of eye relief. If this is true, I'm surprised you cannot see the entire field stop even without glasses. Care to comment more on this?<<<

Maybe not quite enough eye relief with glasses, and some blackout (too much eye relief) without glasses? I too can't imagine 20mm not being enough without glasses.

--------------------
Patrick

8" f/6 NewStar dobsonian
Orion Starblast 4.5" f/4 mini dobsonian
42mm SuperView, 17mm Nagler T4, some other cheapies
Omcon 7x50, Oberwerk 11x56, Olympus DPS-R 7x35, Olympus Magellan 8x25
homemade 50mm right-angle bino-scope prototype


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ronharper
Carpal Tunnel


Reged: 02/14/06
Posts: 2065
Re: Fujinon FMT 50mm: 7x SX vs 10x SX2 new [Re: patter1]
      #1165409 - 09/25/06 07:30 PM

Thanks to you all for wading through my longish piece, and for your kind remarks and questions.

Rich, Patrick, and Bill,
I will try to get to the bottom of the eye relief problem in the 10x that is keeping me from seeing the entire field. I just measured the distance from the eye lens glass to the top of the extended rubber eye guard in both binos.
In the 7x, which has a claimed eye relief of 23mm, the distance is 18.8mm.
In the 10x, with a claimed eye relief of 19.8mm, the distance is 14.8mm. So, the 7x appears to get the eye about 1mm closer to the advertised location. The wider field of the 10x also puts greater requirements on eye relief than the narrow field of the 7x. I have often experienced this with telescope eyepieces, but don't really understand it. In a 40 degree Ortho, 7mm of relief is just fine, but in a 50 degree Plossl with this eye relief it is nearly impossible to view the entire field.

I went out in the sunshine, rolled the eye guards on the 10x down, and tried it without glasses. Now, I could see to the edge of the field, but experienced bad kidney bean blackouts when I rolled my eyes to look near the edge. I know from using Nagler eyepieces that the kidney beaning is worse when the eye's pupil is closed down. I will try this later in the dark.

Attention John C., do you have this problem with your 10x50?

Rick,
The housing says 6.5 degrees.

Ron


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ronharper
Carpal Tunnel


Reged: 02/14/06
Posts: 2065
Re: Fujinon FMT 50mm: 7x SX vs 10x SX2 new [Re: ronharper]
      #1165863 - 09/26/06 12:45 AM

This continues the experiments with the 10x from the previous message.

Under the stars, the kidney beaning effect with the eyeguards down is much less than in daytime, but still there. The eyepieces are behaving like my 12mm Nagler type 4 which has a click adjustable eyeguard: Get too close, see the whole field easily, and suffer from kidney bean blackout. Get too far away, and the kidney beaning ceases, but you lose some field. Not good, but high-classed problems!

I don't like KB, and also I didn't like the hard feel of the rolled-down eyeguards, which I had to touch lightly underneath my eyebrows to get the distance just right. So I rolled them back up, and found that I could get the entire field by just pressing the bino a bit harder. It's just a bit uncomfortable to get the whole field, which did in fact measure the full claimed 6.5 degrees across. I think we're in a zone here where what you get depends on your facial structure. Mashing on the raised eyeguards is still more comfortable than hitting the lowered ones, and much steadier, as the the head is lending some nice support. In fact the bigger your head, the fatter, more muscular, more brainy, whatever you can bring to the table to add inertia to those eyepieces, the greater advantage this technique will bring. For me it's comfortable to get 6.3 degrees, which still looks a tad vignetted but the sharp edge can be seen in the shadow.

With my clunky eyeglasses on, which I don't observe with since my astigmatism is weak, but donned just to report to the actual glasses wearers, I still can't get but 6.0 degrees with the eyeguards down. I would guess that modern, small, close, thin eyeglasses would do better.

Thanks, guys, for questioning my statements about eye relief and field. The process led to understanding. That is what this forum is for, right? That, and spoutin' off!

Ron


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Rich V.
Post Laureate


Reged: 01/02/05
Posts: 3143
Loc: Lake Tahoe area, Nevada, USA
Re: Fujinon FMT 50mm: 7x SX vs 10x SX2 new [Re: ronharper]
      #1165909 - 09/26/06 01:41 AM

Well, at least know you're getting the full FOV you paid for! It also shows that the 10x50 has a bit more ER than the 16x70s. Now you have to decide if mashing the eyecups is OK for you or not. You can always apply some foam or felt donuts onto the rolled back eyecups to act as spacers that hold your eyes back to the "just right" spot without blackouts. Just a fraction of an inch would do it.

Like you say, it's all about facial structure. I like to support the binoculars by pressing the eps against my browbones. If it takes a spacer of sorts to get the relief just right, so be it!

It's too bad such fine optics as the Fujis don't have the little ergonomic touches to go with it. Modern multi position "twist up" eyecups found on even mid priced roofs would do a fine job in this case. I guess you can count on nothing being perfect!

Good luck with the new bins.

Rich V

--------------------
Binoculars:
33/50/71/150x100 Saturn III, 22x70ED, 16x70 FMT-SX, 10x50 PCF-V, 10x43 DCF-SP, 10x35 EII, 7x35 E, 8x30 EII,
7x26 Custom, 8x23CF AS Diplomat, 6.5x21 Papilio
Scopes:
C9.25, TMB130SS, SV80S-LOMO 80/480
IDA member


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KennyJ
The British Flash


Reged: 04/27/03
Posts: 20139
Loc: Lancashire UK
Re: Fujinon FMT 50mm: 7x SX vs 10x SX2 new [Re: Rich V.]
      #1165936 - 09/26/06 02:32 AM

This very critical eye relief problem appears to be the same as many experience with the Nikon SE range .

Bill Tschumy came up with one solution which I found particularly appealing , of sticking neoprene washers of just the right thickness to the inside of the existing rubber eyecups with rubber cement .

Kenny

--------------------


Milton Wilcox R.I.P






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