Archives of an email list on the history of binoculars



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Archives of an email list on the history of binoculars.

http://home.europa.com/~telscope/listp100.txt

home page: http://home.europa.com/~telscope/binotele.htm
101-150

Binocular List #101: 24 April 2000. Fujinon 70mm, Mirakel, Sans & Streiffe 999

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Subject: New (?) Fujinon 70 mm models

Fujinon has an economy model of their 10 x 70, & 16 x 70, binoculars. The FMT-SX models are the old standard, "flat image plane... enables observation of the marginal area of a visual field, sharper, more true to life colors, and minimize distortions and astigmatism"; also "every lens and prism surface is coated with a special new EBC process".

The 10x & 16x MT-SX are 70mm, with identical specifications, but apparently without the 'flat image' corrector lens; and the "EBC coating is applied to all lens surface in contact with the air" (it is unclear if both product lines are fully EBC coated -- are they saying that the binoculars are nitrogen purged, so there's no air contacting the inner surfaces?.) http://www.fujinon.co.jp/products/optical/bn01.htm

My local astronomy club is looking to buy a big binocular; anyone who's used both lines could provide some needed input. Thanks, Peter

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Subject: Mirakel

From: Bob Bibb, rbibb@___.com

I have a small glass marked mirakel, it's 7-17.5 Its marked on the top hinge 7-65, it doesn't make sense. It's made of plastic like material for the body and eyecups, the rest metal. It's harwix- berlin on left cover and mirakel on right. If I can help any other way let me know. bob bibb

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From: hans.t.seeger@___ne.de (Seeger)

Today, I can tell something about the "MIRAKEL" binocular. I have one of these small prismatic binoculars, Ser.-No. 5156, with individual eye focusing. The body is of black vulcanite and the shape is peculiar and only to be found on this glass. The weight is 130 grams. The glass has apparently Porro I prisms but I have not opened it. On the upper left the manufacturer's name is given - the letters raised and part of the cast body: HARVIX BERLIN. In the same way there is on the right the word MIRAKEL. (Mirakel is translated miracle). On the brass washer top center the magnification is given: 3 1/2. The objective diameter is about 13 mm. The height of the small beautiful glass is 4.8 cm. Best regards Hans

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Subject: Sans & Streiffe Model 999 7x35

From: Dick Buchroeder, rab@___net.com

Gentlemen,

Phil Lam and I finished measuring the eyepiece lenses for the S&S, a 12.5-deg 7x35, and the one that I've found to perform superior to any other that I've used so far.

I contrived an objective and prisms to match. The eyepiece is the only complicated thing about a binocular.

You don't want to even KNOW how much astigmatism something like this has over its 88-deg apparent FOV (about 20 diopters), but the computations agree with one's visual observations on terrestrial and stellar objects. However, S&S did an optimum job under the circumstances, and used high index glass throughout the eyepiece, BAK4 prisms.

I looked again at the lens drawing and the astigmatism plots, and asked myself, "what would happen if that one singlet, that looks like it's turned around (based on experience), were reversed in direction.

So, I turned it around and raytraced it. The astigmatism is cut in half, and the tangential focus is made flat...which as you know from my constant harping is the way it should be! The S&S as assembled produces a flat medial focus.

I took the working half of the binocular out tonite and looked at lights, and confirmed that indeed edge-of-field blurs do seem to agree with the computed as-designed/assembled S&S lens orientation, NOT with my preferred flat T-field.

There is no way one can accidently have the elements reversed, because the spacers will not permit it: glass will clink on glass. Neither of the two relevent spacers can be used unless both of the singlets indicated are oriented as they were when I disassembled the eyepiece.

This is pretty exciting for me! It means that I can improve the performance of the S&S #999, which I ALREADY find superior to any other 7x35x12.5 commercial binocular I've ever used.

The problem is, I need to get a couple of new spacers made.

One is easy: its a straight cylinder with parallel ends. The other has to step down and have a semi-conical shape, correct on the outside to fit the lens barrel, and correct on the inside so as not to intrude excessively on the lens clear apertures. And everything has to be looked at closely to be sure the assembly in fact will 'tighten up' when its screwed back together.

>If there is extreme astigmatism at the edge of the field, is the astig

>halfway to the edge a variable? Can an ocular 'fall off' less than another

>ocular with similar edge blur? Is this a variable, or if there is (say) 20

>D astig at the edge, will there usually be (say 5 D) halfway to the edge?

In the S&S 999, there is considerable overcorrect 3rd order astigmatism, so that the S-focus curves 'inward', dominated by the Petzval sum, while the T-focus curves 'outward', and the medial or average focus is 'flat'.

When the eyepiece element is reversed, 3rd order astigmatism is very low, so that both T and S curves follow the Petzval curve (undercorrect, inward curving), until finally 5th order astigmtism kicks in and sends the T-curve rightward, overcorrect; just enough to make the T curve nearly flat, but at least crossing over the plane that goes thru the on-axis focal point.

In the nominal case, T and S curves are essentially parabolic, so that if you double the field, you quadruple the departure from the flat focal plane.

I find that my eyes get along pretty well with about 3 diopters of astigmatism, and this is common in ALL the older binoculars, even the best, with a 55-deg AFOV. After that, all bets are off! But, better to have a wide blurry field than a small sharp field. Regards, Dick.

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Subject: reviews of Fujinon 25 x 150

www.cloudynights.com

http://www.monkoptics.co.uk/binoculars/Astronomy/Fuji_25x150review.html

This one shows a Canon 5 x 17 held to the eyepieces of a Fujinon 25 x 150 to boost magnification.....I'll have to try that one.

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Binocular List #102: 02 May 2000. Fujinon 10 x 70, more on Aberdeen

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Subject: Fujinon 10 x 70

From: Peter Abrahams

It was pointed out to me that, contrary to my last post, the newer, less expensive Fujinon Poseidon 10 x 70 has very limited eye relief of 12mm.

I had a chance to compare the Fujinon Polaris 10 x 70 (about $540 discounted) with the Nikon Astroluxe 10 x 70 (about $1200 discounted). Both are very nice binoculars, the Nikon is superior but not $660. better. Both are waterproof, individual focus, and fairly heavy; the Nikon does not have a tripod adapting 1/4 -20 hole.

The Fujinon has oculars that are 50 mm in diameter, the Nikon has 40 mm oculars. As expected, the Fujinon has better eye relief, but the difference is nowhere near as large as could be expected from the size difference. Neither have adequate eye relief to use with spectacles; the field stop of the Fujinon disappears as the binocular is moved a very short distance away from the eye, but the field does not contract as quickly as with the Nikon, where the field becomes much smaller as the glass is moved a slight distance from the eye. I'm not bothering to quote the specifications for eye relief, because the figures are unrealistic. The 50 mm eyepieces of the Fuji are too large for me, I cannot fit them around my nose when they are closed to my 58 mm interpupillary distance. Both binoculars have a rather limited field of view of 51 degrees. Both are quite sharp to the edge of the field, with the slightest bit of pincushion distortion.

I like to test contrast during the day by looking at old weathered wooden boards, the color gradations are very subtle. The Nikons use 'ED' glass, and the difference is slight but real; with very slightly contrasting colors being more visible in the Nikons. I have compared the Nikons with Fuji 16 x 70s at night, and the difference was noticeable: the Nikons rendered nebula as white or colorless, compared with a less brilliant, slightly green shade to the Fuji image.

Both glasses are nicely baffled, but not perfectly so; viewing a bright light shows arcs of reflections off metal surfaces out past the edge of the field. The Fuji has a more uniform flat black interior, while there are more shiny metal surfaces showing inside the Nikon. However, the Nikon shows outstanding contrast in use, so the differences are academic.

Finally, both binoculars reek of outgassing plastic, the Nikons stink in spite of being some years old & even after extensive washing with various soaps & solvents. I am considering stripping the vinyl covering off of them, as I find the smell offensive, but it takes some courage to strip a binocular this expensive. The Fujis have a similar odor but are new, so there is hope for them.

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Subject: Fuji MT vs FMT 10x70


From: "Loren A. Busch"

Haven't compared under dark skies, but we carry both in the store (at least at Lynnwood) and the only apparent difference is the eyepiece and color of the markings. I'll check our literature and see if they go into any more details on the coatings.

One of the less known advantages for the Fujinon MT and FMT 7x50 and 10x70 series is the availability of screw on filters, including nebula filters, directly from Fujinon. They will also make custom prescription adapters for people that need the correction instead of eyeglasses.

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Binocular List #103: 09 May 2000.

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Subject: Bino-building; new Russian giant

From: Fan Tao

This website shows a binocular shaped sculpture/building near Los Angeles,

perhaps a future meeting site for binocular list members?

http://www.usc.edu/isd/archives/la/pubart/sculptures/binoculars.html
There was a recent ad on Astromart for giant binoculars, from astrostuff.com. I didn't see any information on that web site on these binoculars, however, so I don't know if they are available from them or if this was a one time deal. The ad was from only a week ago but it doesn't appear to be on Astromart anymore.

NEW AMTc Giant 20x140 Binoculars with no glare coatings on both lens.

500mm FL; f3.5; 7mm ER [seems kind of short]; 10" red. [?]; 4 deg FOV; 50lbs; $3000 + S&H; Made in Russia.

I wonder how much chromatic aberration there is with such large objectives at an f/ ratio of 3.5.

Regards, Fan Tao fantao@___et.att.net

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Subject: Nikon 10x70, 6.5 degree on Mauna Kea 4/30/00

From: rab

I lugged those big, heavy Nikons to Mauna Kea with me last Sunday. I showed up at the Onizuka Visitors Information Center, at 9300', before sunset. A bunch of tourist vans were in the parking lot, and while I was wandering around, one of the van drivers approached me and asked if I wanted to pay $25 for a trip to the peak to see the sunset. Naturally, I said yes! Went up, wind was nearly still, clouds down at about the 5000' level (the Peak is at about 13,740'), and it got cold fast as the sun started sinking. Along with scanning the scenery with the Nikons, I guessed that it would be worth watching the sun sink down into the cloud layer...which was below local horizon. As the sun descended into the cloud layer, I noticed the start of a Green Flash, and watched it develop into a lengthy (several seconds) set of brilliant emerald green striations. At 10X!

The van then returned everyone to the 9300' level for viewing without bothering the astronomers. The visitor center has several telescopes, including a Meade 16" LX200, which was out for the public under control of a volunteer amateur astronomer. Who just happened to have come in from Canada and was recruited for the purpose. I didn't take his name down, but he was friends with the Canadian astronomers (CFHT telescope, I imagine) on the Peak, and has spent a night up there with them. I asked him about stargazing at the peak. He said that he made magnitude estimates up there, and got down to only 5.8. At the 9300' level, he was getting down to 7th mag. So the anoxia effect that people talk about seems substantiated again.

Anyway, I didn't go up there to look thru a crummy SCT, so I took the Nikons away from the crowd and viewed to the south. Unobstructed horizon in that direction (to the West, the zodiacal light was a nuisance), at latitude about 22-deg, of another 10-deg better than Tucson. So, I got to see a whole bunch of Milky Way objects not visible from here, and a better view of some that are, like Omega Centauri. How wonderful to have a big pair of quality wide-angle binoculars! Simply wonderful! Regards, Dick.

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Subject: Signal Corps Engineering Laboratory

From: Peter Abrahams

Yet another wartime optics lab was at the Signal Corps Engineering Laboratory, at Camp Evans, Monmouth County, New Jersey, 2000 acres which was part of Fort Monmouth. During the war years of 1941-1945, 3000 officers and civilians worked at Camp Evans. The most significant work done there was on radar, but Squier lab, the 'components, battery, photographic and testing laboratory', included an optics shop. This is where the the Carl Zeiss collection of photographic lenses was taken, along with other captured military optics, for evaluation.

http://www.infoage.org/nrhp.html#SigCLab

Kaprelian, E.K. Recent and Unusual German Lens Designs. J.O.S.A. 37 (6/1947), 466-471.

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Subject: Sears 10x50 DISCOVERER, model no. 6268

From: rab

Gentlemen,

After lately accumulating a bunch of doggy binoculars on eBay, I finally achieved some measure of success: bought a Sears 10x50 with a marked field of 400' at 1000 yards, amber coated, in extremely good optical and mechanical condition!

It is still in collimation, and the zero diopter differential is still correctly set (almost unheard of in the old binoculars I've bought thru eBay). It looks as though it was seldom if ever used, although it's case is warped and was probably rained on. No deterioration of any kind in the optics or metal.

As with ALL the Sears stuff I've bought on eBay, it is characteristically deficient. In this case, its prisms have much too low a refractive index, and squareness of pupils is severe. I previously owned a 7x35 Sears Discoverer, and this looks very much like a scaled version of it.

Did my after-dark testing tonite on city lights, and on real stars.

One can always tell if there is the POSSIBILITY of a parasite image by examining the exit pupil with a magnifying glass. Thus, I could see a couple of small, slit-like areas where there might be such images and I looked for them on the city lights that fill my eastern horizon. It was difficult to find the parasites, but some do exist: if the binoculars are held below the lights and I look carefully, spurious overlaid images occur. However, it's actually difficult to make them appear, compared with most other binoculars where they are a conspicuous annoyance. This despite the low-index prisms causing significant squaring of the exit pupils. The general ghosting situation was quite good; no sharply focussed ghosts, remaining ghosts subdued. The Sears binocular is testimonial to the fact that even with small, low-index prisms it is possible to minimize or eliminate spurious images and ghosts.

I found the plastic eyecaps to obstruct parts of my field of view, in exactly the same way that similar appearing caps make the Bushnell Rangemaster 7x35 inferior to the otherwise similar Swift Holiday Mark II 7x35. One's face is not necessarily symmetrical and brows will interfere with well-intentioned but ill-advised symmetrical eyecaps. Fortunately, I was able to remove one easily, and the other with some difficulty. (The plastic eyecap on one was stuck to the metal eyepiece retainer, and both were removable as a unit, but sheer finger-force wouldn't separate them. Last time I tried this I managed to break the plastic by using padded pliers, so this time I tried a different method. I put the stuck parts into a coffee cup half-filled with water, stuck in a microwave over for 90 seconds, and the different expansions made it easy to unscrew the two parts).

This now made it easy for me to fit the binoculars, both sides, to my eyes and facial features. The field stops are now sensed entirely around the field of view with both of my eyes, and things are no longer painfully bumping into my face. There were also some other subtle advantages to removing the plastic eyecaps. There is sufficient depth to insert corrective spectacle elements onto the 24mm clear aperture eyelenses, but unfortunately I've run out of them.

Nonetheless, despite my 2.5 diopters of astigmatism, I can sort out what's in the binocular from what's in my eyes and so I tested the binoculars on the stars as well as the city lights. I also did small-field testing wearing my glasses.

The tangential field is not flat; the medial focus tends to be flattest, which is not optimal in my opinion. The pupil aberration is well-behaved, and there is no kidney-beaning; it is very comfortable to use these binoculars. Color correction both axial and lateral is correctly done. Overall, these are very pleasant glasses for city and star gazing.

The square exit pupils are not causing any apparent artifacts to detract from the image, although in the end they must at least 'apodize' a wide-open eyeball's pupil and give some subtle diffraction spikes on bright objects, as well as cause transmission loss, especially off-axis. However, under bright city light conditions, I saw no evidence of this. Indeed, where there is often a 'ring of light' effect (for example, in Fujinon 16x70 binoculars) caused by pupil aberration and consequent field vignetting by the eye's pupil in some if not many binoculars, I was unaware of this occuring in these when I tested them earlier in daylight. I'll be looking again to see for sure.

Physically, the Sears Discoverer 10x50 is about 3/4" shorter in length than my much-esteemed Bushnell Custom 10x50. This makes them somewhat more comfortable to hold.

The bridge mechanism is flimsy and rocks, but experienced bino users know how to deal with this. The prism covers are bent sheet metal, not as tight as I'd like for dust protection. Otherwise, everything looks and feels solidly built.

Except for the failure to use higher index prism glass, these are really very excellent binoculars, as was the 7x35 Sears Discoverer. As far as I can tell, there is little penalty for this shortcoming for daytime use, an opinion I've held for many years based on my prior experience with certain other low-index prism binoculars. I would be delighted to hear opinions to the contrary.

There are no markings indented or otherwise to indicate which Japanese factory these came from.

Their amber coatings suggest they come from the 1960 era. Regards, Dick.

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Binocular List #104: 16 May 2000. New Zeiss models, new source for reprints, meeting in L.A., Univex

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Subject: New Zeiss models.

"The Revolution in Binocular Design".

Zeiss Victory 8x40 B T*, 10x40 B T*, 8x56 B T* and 10x56 B T* Binoculars

New four-element Superachromat lenses to prevent color fringes caused by secondary spectrum and to achieve a short overall length. [triplet, & meniscus singlet that appears to focus the binocular]

Lens elements with reduced center thickness and prisms of new, lighter types of glass for less weight.

8 x 56, eye relief 17.5mm, FOV 405' / 1000 yds, diopter +- 4.5

10 x 56, eye relief 15.6mm, FOV 330' / 1000 yds [63 degree apparent field], diopter +- 4.5, 5m close focus, weight 1200g, "the first handheld 10x binocular with a 56mm objective"
Abbe-Koenig prisms ("with twice the volume as the Pechan prism as used by Swarovski, Leica....").

Zeiss T* multicoating matched to AOS for light transmission of over 90% in the spectral ranges where the eye is most sensitive by day and night.

Internal focusing for optimum waterproofness and sealing against dust.

Push-pull eyecups which can be locked in position (viewing without eyeglasses).

Waterproof in compliance with DIN 58 390 80 (submersion).

Filled with nitrogen to prevent internal fogging.

Rubber-armored to provide improved grip in rain and cold.

Practical tripod adapter for 1/4 and 3/8-in. threads.

The optics have been designed using the Advanced Optics System (AOS) from Carl Zeiss.

In the past, to build binoculars providing maximum image quality and performance, glass types were needed whose optical properties were only achieved by adding lead, arsenic or other metals. These additions have a high specific density and the binoculars, especially models with high magnifications and twilight performance, are correspondingly heavy.

After many years of intensive cooperation with Zeiss optical scientists, Schott Glas, Mainz, a company of the Carl-Zeiss-Stiftung and the world's biggest special glass manufacturer, has now succeeded in producing glass types without arsenic and lead, providing the optical properties required for systems of maximum image quality. The new glass types from Schott are markedly lighter, and their processing does not require the disposal of environmental pollutants.

http://www.hensoldt-zeissgruppe.de/default.asp

http://www.hensoldt-zeissgruppe.de/en/news.asp (English)

Also, Anacortes Telescope has posted the English brochures for these: http://www.buytelescopes.com/

They also show a Zeiss 3 x 12 B Triple XXX Monocular, which can be fastened to the ocular of a Zeiss binocular to triple the magnification.

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A historical note mixed in with the sales:



Without eyeglasses, the necessary eye relief is achieved with Zeiss binoculars in three different ways: eyecups with a push-pull mechanism*, eyecups with a rotating mechanism*, and fold-down rubber eyecups.

*As far back as 1954, Hensoldt applied for a utility patent for this type of adjustable eyecups and hence played a major role in the development of binoculars at a very early date.

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Subject: Source of reprints

From: "pernice"

I have found last month a web site where you can find copies of several manuals of military optics like rangefinders and other optical instruments. http://www.military-info.com/aphoto/Subjectlist/photomenu.htm

you must search at "optics " jean laurent

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Division of Military Engineering of the International Congress of Engineers. "Range and Position Finding for Purposes of Gunnery," by William Oliver Smith. Columbian Exposition (1894),XI.; 28 pages Price 3.00 {Item No.6111}

Reports of the Chief of Ordnance and Board of Ordnance and Fortification. Test of Telescopic Sight with Vertical and Hortizontal Hairs," Annual Reports of the War Department 1902 Volume VII, Appendix X.; 3 pages Price 1.00 {Item No.5411}




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