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Posts Made By: Alan Birnbaum

February 24, 2003 10:25 PM Forum: Birding Optics and Photos

Pentax DCF SP 10 x 43 aspheric roof prism

Posted By Alan Birnbaum

On another board, someone mentioned the pending availability of the Pentax DCF SP 10 x 43 binocular, which was news to me. Apparently, this is a 6.0 degree field unit, with 17 mm ER, and 2.0 m close focus, with some aspheric components, that seems very light, at 24 oz, for a fully sealed and fogproof roof prism glass. It will carry a semi-premium price of $649, according to the Anacortes listing.

Has anyone actually seen such a pair? If so, how flat is the field? Any idea how they might compare to, say, the Zeiss Victory T 10 x 40, or the Swarovski EL 10 x 42? Thank you for any information.


Alan Birnbaum
Fresno, CA

March 11, 2003 12:21 AM Forum: Birding Optics and Photos

Zeiss Victory II B T* series

Posted By Alan Birnbaum

Might anyone have actually seen an example of the newly introduced Zeiss Victory II B T* series? I came across an announcement for such, in the 8 x 40 and 10 x 40 sizes, on the Zeiss website. Supposedly, the improvements include better multicoatings, improved strap fitting, better center focus, improved rubber coating, and, what might be an extra mm eye relief on the 10 x 40 model. One vendor had become just aware of them, and understood only that the price would remain the same. I have seen the original Victory in the 10 x 40, and they do seem very nice.

Alan Birnbaum
Fresno, CA

March 18, 2003 09:20 PM Forum: Equipment Talk

Eagle Optics Ranger vs. Zeiss Victory

Posted By Alan Birnbaum

I'm considering purchase of a 10 x 40/42 roof prism to be my main birding binocular, as the local Audubon crowd here in Central California recommend 10X over 8X. They do a lot of field trips to NWR's. Might anyone who has used both be able to explain what I might gain by purchasing the Zeiss Victory (now II) over the Eagle Optics Ranger (now Platinum Class), besides perhaps 0.3 degrees of field?

I know that the Zeiss is a bit longer, and weighs a bit more, of course. The EO actually has a closer focus. Eye relief for either one is 16 mm, likely adequate for me, based upon my current use of the EOPC 8 x 32 (which I like very much for walk-arounds in my neighborhood.)

Mainly, to what extent would there be a VISIBLE difference during actual usage? Specifically: brightness, field flatness, center resolution, etc.

I KNOW what the difference would be in cost, of course! Thanks for any input.

Alan Birnbaum
Fresno, CA

March 20, 2003 05:51 PM Forum: Equipment Talk

converting Sigma 600/8 mirror lens to spotter

Posted By Alan Birnbaum

I just realized that the old, barely used, Sigma 600 mm f8 catadioptric mirror lens potentially might be usable as a spotting scope, IF I could find a source for an adapter that would convert a Nikon bayonet mount, to something that would take a 1.25" mirror or prism diagonal. Coupled with a Meade 18 mm SWA telescope ocular, that would give me a 33X scope with a 2 degree field. It wouldn't be weather proof, but we get very little rain here in Central California 8 months out of the year.

Can anyone recall a potential source for such an adaptor? Thanks

March 20, 2003 11:16 PM Forum: Birding Optics and Photos

Minox BD 10x25BR folding roof prism binoculars

Posted By Alan Birnbaum

I decided to purchase a pair of the Minox BD 10x25 BR weatherproof (but not waterproof) compact binoculars, over the Zeiss and Leitz in part because they were 1/3 the price, but also because they promised a bit more eye relief (I wear fairly thick glasses), and had a closer focus.

The eye relief seems almost too much! Clearly at a marked 17 mm, it's functionally more than that on the Eagle Optics Ranger 8 x 32 I have, which are marked for 16 mm. The feel of the rubber coating is very good, not only on my fingers, but where the eyecups contact my glasses.

The specifications marked on the data sheet indicated a close focus not of 3 meters or so, but 1.6 meters! I have just tried them, and can report that the close focus is right around 5.25 feet, MUCH less than what any website source indicated, including that of the manufacturer!

On the downside, the rather small diameter focusing wheel seems very stiff. Hopefully, this will loosen usefully with usage. Also, the 3/32" neckcord I find just barely adequate, creating a "toe out" carry position, so the thin cord may be useful mainly for safety purposes, but not for any extended carrying around the neck.

The thin strap attached to the tubes on my older Minolta 8 x 24's seems much more comfortable, though I suspect the Minox are optically better. By the way, one can make the Minox ride "toe in," by putting them over one's neck "backwards," then bringing them up to the eyes in a "crossdraw" fashion.

The supplied padded nylon belt case is excellent, and includes an outside slit pocket (into which I have put my business card), though I suspect it was meant as a secure storage area for the eyepiece caps.

These will not be my primary birding binoculars, but for their intended purpose, every day briefcase carrying, I think they should work well. Locally much of the casual birding would be of birds that gather, usually of course on the FAR side, of various ponding basins used locally for groundwater recharge, and flood control. That makes 10X more useful than 8X. For walking around my neighborhood, on the other hand, I think I'd prefer my 8 x 32's, due to the better strap, wider field, and likely much more close range peering upwards.

Alan Birnbaum
Fresno, CA


April 3, 2003 06:59 PM Forum: Birding Optics and Photos

Avian Aliens in Paradise

Posted By Alan Birnbaum

Funny to see how many non-native species predominate here in Honolulu. I saw my first pair of Northern Cardinals here yesterday in Kapiolani Park, on the east end of Waikiki, ironic as this is the state bird of no fewer than SEVEN states, all of them east of the Mississipi. The Red-crested Cardinal seems quite common; it's originally from Brazil, I understand. And, that doesn't even start to consider the Common Myna, Java Spara, Bulbuls, Cattle Egrets, etc. Birds that are native to Hawaii so far have been in the minority.

So, basic birding on Oahu seems to be a clearcut case of avian aliens in paradise!

Alan Birnbaum
temporarily in Honolulu, HI

April 8, 2003 03:18 AM Forum: Birding Optics and Photos

Best Bean birder belt bag

Posted By Alan Birnbaum

See:

http://www.llbean.com/webapp/wcs/stores/servlet/CategoryDisplay?categoryId=30142&storeId=1&catalogId=1&deptNum=203#detail

for the LL Bean "Travel Fanny Pack," now $20, and available in navy, black and green, that I have found to work so nicely for smaller guide books, even a pair of them, plus as local listing sheet, pen, etc.

Of course, it was all I could do to complete this post, as my ex-ballerina wife came flitting into the room, chirping, and demonstrating the "Bluebird" ballet steps from a piece she had done a number of years ago. REALLY!

Alan Birnbaum
Fresno, CA

May 5, 2003 07:02 PM Forum: Birding Optics and Photos

initial impression, Pentax DCF SP

Posted By Alan Birnbaum

I have just received my pair of Pentax DCF SP 10 x 43, and am favorably impressed. Illustrations from the Web seem very accurate, but don't show the thumb cut-outs on the bottom of the barrel, which I had anticipated they'd have. These make them comfortable to hold. Overall, they feel VERY solid. They are at least half an inch shorter than the Zeiss Victory, or the Swarovski EL.

Compared to my Eagle Optics Ranger Platinum Class 8 x 32, these are rather similar, but improved in a few ways. The field does seem flatter. The eyecup has subtle detentes, not that that mattered to me, as I always use mine completely down.

The eye relief, listed as 17 mm, does seem a bit better, i.e., I can more easily see the edge of the field, compared to my current, smaller Ranger. The apparent field of view, 60 degrees, seems the same.

The Pentax have a slightly better rain shield design, and a distinctly better objective cover. On the DCF SP, these fit inside the objective frame, and came attached to the front of the hinge, which can be used for tripod mounting, given a special adaptor (not that I'm likely to use them that way.)

Weight is as advertised, after I allow for the weight of the rainguard, and the objective covers, at 25.7 ounces. Obviously they're 35% heavier than my 8 x 32 's. The dark green protective rubber is attractive, as is the matching case, smooth cordura in a matching shade, and better than the Eagle Optics, with a naugahyde reinfored bottom.

While I don't normally adjust the diopter, these come with a way to lock that, that works very simply. With my thumbs placed in the cutouts, the strap lugs do not contact my hand (as was bothersome on the just remodeled Zeiss Victory.)

My first quick look outside detected across the street something perching atop a building, maybe 200 feet away. Interestingly, it proved to be a Western Scrub Jay, the first bird on my lifelist. Yes, I can tell there's a little shake in the view I don't get with my 8 x 32, but I think it will be acceptable for ordinary usage.

I'll file another report, in perhaps a week, once I have a chance to use them for a more extended period in the field.

Alan Birnbaum
Fresno, CA

May 6, 2003 01:16 AM Forum: Birding Optics and Photos

depth of field for binoculars

Posted By Alan Birnbaum

Allow me to pose one question for discussion. What determines "depth" of field for terrestrial binocular usage?

My presumption is that "depth of field" or "depth of focus" simply varies inversely with the relative magnification of the object, and has almost nothing to do with the nominal power of the binocular, or its aperture.

I don't think that it really varies with the make of the binocular, as long as we're talking about the same magnification. Of course, I'd expect that the "depth" does improve in better light, simply because one's iris closes down to as little as 2 mm.

But, beyond that, shouldn't the "depth" of focus apparent in my 8 x 32 at 8 feet be the same as in my 10 x 43 at ten feet, or my 18 x 50 at eighteen feet, particularly if I'm using them in fairly bright light where my pupil is 2.75 mm or less? That would be the case because the apparent size of the viewed object is the same.

And as a secondary issue, would the nominal f-ratio of the basic lens, the doublet or triplet objective lens, make any difference? I doubt that it should.

Thanking everyone in advance for their interest, and contribution.

Alan Birnbaum
Fresno, CA


May 27, 2003 05:27 PM Forum: Birding Optics and Photos

on the other end of the binoculars

Posted By Alan Birnbaum

Ever wonder how sharp-eyed might be that bird on the other end of your pair of expensive binoculars? Here's part of a current interview from the Gary Hull, head of the Golden Gate Raptor Observatory, near "Hawk Hill," on the Marin County Headlands, just north of the Golden Gate Bridge:

<
Yes. The sight receptors in the back of their eyes are far more densely packed than ours; their eyesight is 10 times keener. To understand how well they can see, just look through 8X or 10X binoculars. With this eyesight, the raptors are very aware of their environment. They're totally focused.>>

That was published in today's San Francisco Chronicle. Apparently, hawks are BORN with built-in Swarovskis! The GGRO has its own interesting website:

http://www.ggro.org/