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Showing results 1 to 25 of 173
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Search: Posts Made By: John A Roberts
Forum: Vortex Yesterday, 05:55
Replies: 40
Views: 1,307
Posted By John A Roberts
and the graph from Vukobratovich John

and the graph from Vukobratovich


John
Forum: Vortex Yesterday, 05:53
Replies: 40
Views: 1,307
Posted By John A Roberts
As David indicates in posts 15 & 19, there are a...

As David indicates in posts 15 & 19, there are a whole range of considerations, including variations depending on the light intensity/ degree of darkness

For the technically inclined, Holga Merliz (...
Forum: Leica Friday 19th July 2019, 04:25
Replies: 4
Views: 289
Posted By John A Roberts
Duovid Optical Construction

Unique among the premium brands, Leica offers a binocular with a limited ‘zoom’ capability - the Duovid
More correctly it’s a dual magnification system, with the higher magnification providing a 50%...
Forum: Swarovski Tuesday 16th July 2019, 20:27
Replies: 6
Views: 427
Posted By John A Roberts
The x32 EL chronology is: - mid 2003 to late 2011...

The x32 EL chronology is:
- mid 2003 to late 2011 - EL
- late 2011 to mid 2015 - EL Swarovsion (new optics and body)
- and from mid 2015 on - EL FieldPro (Swarovision with new covering and...
Forum: Kowa Sunday 14th July 2019, 23:20
Replies: 9
Views: 839
Posted By John A Roberts
Binomania has loaded some initial photos - but as...

Binomania has loaded some initial photos - but as yet no spec's: https://www.binomania.it/presto-in-vendita-i-nuovi-binocoli-kowa-bdii-xd/
see the attached image - a lighter green and more sculpted...
Forum: Binoculars Friday 12th July 2019, 00:00
Replies: 26
Views: 1,039
Posted By John A Roberts
In terms of selecting from 7x42 models, a quick...

In terms of selecting from 7x42 models, a quick overview of the quality choices for birding would include:

A) CURRENT PRODUCTION
Leica Ultravid HD+
Swarovski Habicht Porro

If you want the latest...
Forum: Binoculars Thursday 11th July 2019, 00:42
Replies: 26
Views: 1,039
Posted By John A Roberts
Habicht 7x42 Porro for birding? As many will be...

Habicht 7x42 Porro for birding?

As many will be aware, I’m a fan of the Habicht Porros

BUT for a number of reasons I would not recommend any of them as a general purpose birding bino,
and in...
Forum: Swarovski Monday 8th July 2019, 23:55
Replies: 7
Views: 271
Posted By John A Roberts
nsege Some information so you can get this...

nsege

Some information so you can get this sorted . . .

The Swarovski 8x20 Pocket model was introduced in 1989 (with the 10x25 following in 1992), and production ended in 2013

During the period,...
Forum: Zeiss Thursday 4th July 2019, 09:56
Replies: 8
Views: 402
Posted By John A Roberts
Gijs is correct about the introduction of phase...

Gijs is correct about the introduction of phase coatings by Zeiss in 1988
(verses the 1989 date in my recent post: https://www.birdforum.net/showpost.php?p=3866460&postcount=9 )

His post prompted me...
Forum: Zeiss Wednesday 3rd July 2019, 08:03
Replies: 12
Views: 597
Posted By John A Roberts
Anti-Reflective coating on Schmidt-Pechan...

Anti-Reflective coating on Schmidt-Pechan prisms

I should add for completeness, that as can be seen from the diagram, the facing surfaces of the two prisms perform both transmissive and reflective...
Forum: Zeiss Wednesday 3rd July 2019, 08:02
Replies: 12
Views: 597
Posted By John A Roberts
Correction: Only 1 non-TIR surface on a...

Correction: Only 1 non-TIR surface on a Schmidt-Pechan prism pair

Tenex

You are of course right, there is only 1 non-Totally Internally Reflective surface on a Schmidt-Pechan pair
- the bottom...
Forum: Zeiss Tuesday 2nd July 2019, 04:47
Replies: 12
Views: 597
Posted By John A Roberts
continued . . . Coatings - the original version...

continued . . .

Coatings
- the original version had single coated lenses, aka T coating, and silver (?) coating on the 3 non-Total Internal Reflection surfaces of the Schmidt-Pechan prisms

- in...
Forum: Zeiss Tuesday 2nd July 2019, 04:43
Replies: 12
Views: 597
Posted By John A Roberts
I've had a chance to go through and get into...

I've had a chance to go through and get into order what I’ve collected about the 8x30 Dialyts, so here goes . . .
(I’ve also made a point of indicating where I’m uncertain as to details e.g. there is...
Forum: Others Thursday 27th June 2019, 03:11
Replies: 1
Views: 222
Posted By John A Roberts
Blaser Primus 8x56 Review

Allbinos has just posted a review of the above: https://www.allbinos.com/index.php?test=lornetki&test_l=333
There are some interesting comments as to performance, origin (verses markings) and...
Forum: Swarovski Friday 21st June 2019, 01:29
Replies: 17
Views: 1,596
Posted By John A Roberts
Summary of EL FieldPro changes At the risk of...

Summary of EL FieldPro changes

At the risk of the accusation of pedantry, it seems convenient to document in this thread the full range of changes to the FieldPro version of the EL...
Forum: Leica Tuesday 18th June 2019, 05:04
Replies: 13
Views: 1,004
Posted By John A Roberts
Other Non-Rubber Armoured Ultravids Leica (and...

Other Non-Rubber Armoured Ultravids

Leica (and Leitz before it) has long been a producer of de luxe versions of it’s basic product lines
While these Ultravid offerings are mainly of interest to...
Forum: Leica Monday 17th June 2019, 23:09
Replies: 13
Views: 1,004
Posted By John A Roberts
More re Leatherette Versions The BL/ Blackline...

More re Leatherette Versions

The BL/ Blackline was introduced in 2003 at the same time as the BR
And the SL/ Silverline was introduced in 2010
Both are still listed on the Leica website and both are...
Forum: Leica Thursday 13th June 2019, 23:27
Replies: 13
Views: 1,004
Posted By John A Roberts
The Ultravid chronology is: 2003 - BR 2007 - HD...

The Ultravid chronology is:
2003 - BR
2007 - HD (addition of HD glass in the objectives, AquaDura external lens coatings, and an improved focusing mechanism)
2015 - HD Plus (and Schott HT glass...
Forum: Binoculars Wednesday 12th June 2019, 23:26
Replies: 24
Views: 1,097
Posted By John A Roberts
chicoredneck Taking into account that you are...

chicoredneck

Taking into account that you are concerned with:
- ease of view over long sessions
- and viewing in low light situations

And that you:
- already have a 15x56 SLC (3.7 mm exit pupil)
-...
Forum: Binoculars Wednesday 12th June 2019, 01:15
Replies: 6
Views: 949
Posted By John A Roberts
ADDITIONAL RESOURCES Not to hijack Mark’s...

ADDITIONAL RESOURCES

Not to hijack Mark’s thread, but to provide a one stop starting point for some additional resources . . .


ZEISS
Holga Merlitz has posted a series of catalogues ranging from...
Forum: Binoculars Wednesday 12th June 2019, 01:08
Replies: 6
Views: 949
Posted By John A Roberts
UPDATE - Even More Information Since Mark’s post...

UPDATE - Even More Information

Since Mark’s post in November, considerably more flyers/ pamphlets/ brochures/ catalogues have been added to the Miniature Binoculars site

Manufacturers range from...
Forum: Swarovski Monday 10th June 2019, 21:48
Replies: 14
Views: 1,915
Posted By John A Roberts
Robert You are of course right about Ken...

Robert

You are of course right about Ken Rockwell’s comment as to 7.5 meters being an acceptable minimum focusing distance

FYI some background about Ken:
He primarily writes about photographic...
Forum: Swarovski Monday 10th June 2019, 03:03
Replies: 14
Views: 1,915
Posted By John A Roberts
John I’m not surprised that you had a positive...

John

I’m not surprised that you had a positive experience with the 8x40
Notwithstanding it had the common limitation of roof prisms of the era (a slight image softness, due to the lack of phase...
Forum: Swarovski Sunday 9th June 2019, 09:17
Replies: 2
Views: 348
Posted By John A Roberts
Swarovski Optik on Tour - Mobile Experience

Swarovski has introduced a fleet of vehicles to tour and let people try out its products in the field

There’s a fairly comprehensive list of dates and locations for Europe
And a more restricted list...
Forum: Binoculars Friday 7th June 2019, 22:52
Replies: 37
Views: 2,446
Posted By John A Roberts
In keeping with how diminutive the Mikron is, in...

In keeping with how diminutive the Mikron is, in an early post-WWII flyer it's referred to as the 'shirt pocket' model

Such a carry would maximise it's convenience and use compared to that enormous...
Showing results 1 to 25 of 173
 


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