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Search: Posts Made By: henry link
Forum: Zeiss Friday 19th October 2018, 14:09
Replies: 6
Views: 266
Posted By henry link
Sections 4.3 and 12.2 of "Amateur Telescope...

Sections 4.3 and 12.2 of "Amateur Telescope Optics" cover both objective and eyepiece astigmatism.

https://www.telescope-optics.net/index.htm

On-axis astigmatism from the objective is a sample...
Forum: Swarovski Friday 19th October 2018, 13:41
Replies: 12
Views: 561
Posted By henry link
Fantastic information, John! How were you able to...

Fantastic information, John! How were you able to find all this?

Henry
Forum: Swarovski Friday 19th October 2018, 13:38
Replies: 4
Views: 249
Posted By henry link
A complete change in optics came in 2012 with the...

A complete change in optics came in 2012 with the introduction of the current EL SV. The previous 8x32 EL had a totally different objective lens and eyepiece design and used a positive rather than a...
Forum: Swarovski Thursday 18th October 2018, 22:32
Replies: 12
Views: 561
Posted By henry link
The old serial numbers don't work for dating or...

The old serial numbers don't work for dating or at least don't use the formula Bob mentioned. My 1989 8x30 has a serial number beginning with 94. It clearly wasn't made in 2024.

The one "downunder"...
Forum: Swarovski Sunday 14th October 2018, 12:33
Replies: 25
Views: 1,134
Posted By henry link
Yep, in the old days every Swarovski product...

Yep, in the old days every Swarovski product carried the Habicht badge. In my 1991 catalogue that included all the binoculars, rifle scopes, spotting scopes, the twin telescope and (despite the poor...
Forum: Swarovski Friday 12th October 2018, 23:44
Replies: 38
Views: 1,614
Posted By henry link
Patudo and Robert, You're correct. In the 80s...

Patudo and Robert,

You're correct. In the 80s there was no broad awareness that the roofs were not all they were cracked up to be. Magazine reviewers and big time birders to say nothing of normal...
Forum: Swarovski Friday 12th October 2018, 17:34
Replies: 38
Views: 1,614
Posted By henry link
My first experience with Swarovski binoculars as...

My first experience with Swarovski binoculars as 'alphas" was in the mid 1980s. The binocular enthusiasts I knew then were all quite aware that the roof prism binoculars available, including Leitz...
Forum: Nikon Thursday 27th September 2018, 17:06
Replies: 22
Views: 937
Posted By henry link
Bob, If I were a betting man I'd bet that the...

Bob,

If I were a betting man I'd bet that the same basic eyepiece design was used in all models of both series, then just scaled or tweaked to meet the particular requirements of each model.

Henry
Forum: Leica Thursday 27th September 2018, 15:01
Replies: 73
Views: 3,631
Posted By henry link
John, I'd be interested to know what the...

John,

I'd be interested to know what the advantages of Fluorite are. I recall Roland Christen of Astro-Physics saying about ten years ago that he could make essentially the same scope, whether the...
Forum: Nikon Thursday 27th September 2018, 14:38
Replies: 22
Views: 937
Posted By henry link
Hi John, I think you're right about the...

Hi John,

I think you're right about the cementings not showing well. Looking at the cutaway below I expect the thick objective element is a cemented doublet as well as the two thick lenses in the...
Forum: Zeiss Thursday 27th September 2018, 14:03
Replies: 31
Views: 2,177
Posted By henry link
I didn't say so, but I doubt that they did see a...

I didn't say so, but I doubt that they did see a better measurable resolution (unless the ATX is a very poor unit).

They might have seen a cleaner looking image from the Harpia at 30x magnification...
Forum: Leica Thursday 27th September 2018, 13:46
Replies: 73
Views: 3,631
Posted By henry link
Ronh, Happy to see a new post from you after a...

Ronh,

Happy to see a new post from you after a long time. The small cohort of real scientists here is all there is between the rest of us and the rabbit hole.

Henry
Forum: Leica Thursday 27th September 2018, 13:20
Replies: 73
Views: 3,631
Posted By henry link
Hi Peter, I guess this depends on whether the...

Hi Peter,

I guess this depends on whether the "object" is a black bird surrounded by bright sky or a white bird surrounded by a dark background or my test target's white strips of tape stuck on a...
Forum: Leica Wednesday 26th September 2018, 22:20
Replies: 73
Views: 3,631
Posted By henry link
Classic lateral color. It may be possible to...

Classic lateral color. It may be possible to minimize it with careful IPD setting and trying to keep the eye pupils as well centered on the exit pupils as hand holding allows.

All binoculars will...
Forum: Zeiss Wednesday 26th September 2018, 21:14
Replies: 31
Views: 2,177
Posted By henry link
If this observation was made at lower...

If this observation was made at lower magnifications I think the most likely explanation is that the unbiased observers have higher eyesight aberrations when their pupils are dilated beyond the 2.5mm...
Forum: Zeiss Wednesday 26th September 2018, 15:58
Replies: 31
Views: 2,177
Posted By henry link
Googling something like "star test telescope"...

Googling something like "star test telescope" will turn up lots of information. The Bible on the subject is Harold Richard Suiter's "Star Testing Astronomical Telescopes", which will likely tell you...
Forum: Leica Wednesday 26th September 2018, 14:31
Replies: 73
Views: 3,631
Posted By henry link
The first thing to do is to try to figure out...

The first thing to do is to try to figure out what exact aberration is involved. A little closer examination should pin down what kind of CA is being observed. A fringe that's green rather than...
Forum: Interviews with Optics Retailers Tuesday 25th September 2018, 14:56
Replies: 19
Views: 948
Posted By henry link
I've had the great pleasure of making a...

I've had the great pleasure of making a transatlantic purchase from Jan. There can't be another optics dealer in the world who would have gone to the lengths he did to accommodate my desire to have a...
Forum: Swarovski Monday 24th September 2018, 21:21
Replies: 106
Views: 5,501
Posted By henry link
I agree. It's surprising to me how little it...

I agree. It's surprising to me how little it takes in the way of dust, haze or smudges to create a substantial glare effect when a very strong glancing light source like direct sunlight falls right...
Forum: Nikon Monday 24th September 2018, 13:46
Replies: 10
Views: 346
Posted By henry link
Andy, Bob's right about the price. I found the...

Andy,

Bob's right about the price. I found the 9x30 Execulite in an old dealer price list from about 1988 for exactly $300. By then only the 9x30 and 12x36 were still available. I would call them...
Forum: Swarovski Saturday 22nd September 2018, 17:24
Replies: 106
Views: 5,501
Posted By henry link
You can't have it both ways, Dennis. Is the glare...

You can't have it both ways, Dennis. Is the glare fixed (see post #1) or is it not fixed because that would cause an unspecified compromise (see post #99)?
Forum: Swarovski Saturday 22nd September 2018, 16:58
Replies: 31
Views: 1,400
Posted By henry link
Thanks Ted, Sorry, I thought they were all...

Thanks Ted,

Sorry, I thought they were all recent production. Looks like the 6x30 and 8x30W GA are long gone.

Henry
Forum: Swarovski Saturday 22nd September 2018, 16:26
Replies: 31
Views: 1,400
Posted By henry link
Ted, How did you come up with a recent 6x30M? I...

Ted,

How did you come up with a recent 6x30M? I thought those were long gone.

Has Swarovski resumed offering the 8x30W GA? I was only able to acquire one of those last year by having objectives...
Forum: Swarovski Saturday 22nd September 2018, 15:55
Replies: 106
Views: 5,501
Posted By henry link
Patudo, Keep in mind that a bright sun near the...

Patudo,

Keep in mind that a bright sun near the field edge is not necessarily the best target if your goal is to detect veiling glare. Darker conditions are better since they allow your pupil to...
Forum: Zeiss Saturday 22nd September 2018, 15:42
Replies: 31
Views: 2,177
Posted By henry link
Thanks Kimmo. I hope you get a chance to do a...

Thanks Kimmo. I hope you get a chance to do a more thorough review.

70x seems to be where the objective configuration is optimal. I'll be particularly interested in your star tests and resolution...
Showing results 1 to 25 of 1000
 


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