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Showing results 1 to 25 of 1000
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Search: Posts Made By: henry link
Forum: Spotting Scopes & tripod/heads Yesterday, 16:19
Replies: 5
Views: 286
Posted By henry link
I agree with Joachim. You may find one more...

I agree with Joachim. You may find one more natural and comfortable to use than the other, so you really should try both for yourself. If you see a unit that you really like try to buy that...
Forum: Swarovski Yesterday, 15:49
Replies: 10
Views: 545
Posted By henry link
Winged eyecups can only shield the eye from...

Winged eyecups can only shield the eye from reflections coming from the back glass to air surface of the eyepiece. They don't address the two main sources of glare in the 8x30 Habicht. Those are a...
Forum: Binoculars Friday 18th January 2019, 23:14
Replies: 26
Views: 771
Posted By henry link
I came around to having some of the same...

I came around to having some of the same misgivings about my methods that you expressed, so I deleted my post before you responded. I'll keep playing around with the question over the next few days...
Forum: Binoculars Wednesday 16th January 2019, 17:52
Replies: 26
Views: 771
Posted By henry link
Hi David, Keep in mind that Fig, 16.14 shows...

Hi David,

Keep in mind that Fig, 16.14 shows only the principal rays of the eyepiece alone without a telescope, so it doesn't include the effect of exit pupil size on the size of ray bundles....
Forum: Binoculars Wednesday 16th January 2019, 16:22
Replies: 26
Views: 771
Posted By henry link
It would be radially symmetrical if the eye were...

It would be radially symmetrical if the eye were perfectly centered and perfectly motionless, which it never is when looking through an eyepiece in the real world. If you move your eye intentionally...
Forum: Binoculars Wednesday 16th January 2019, 16:10
Replies: 26
Views: 771
Posted By henry link
Hi Binastro, I think the figure is for...

Hi Binastro,

I think the figure is for illustration only. I suppose including lines for ray bundles would have led to an unreadable confusion of intersecting lines, but it would have revealed that...
Forum: Binoculars Wednesday 16th January 2019, 15:10
Replies: 26
Views: 771
Posted By henry link
This is a side effect of spherical aberration of...

This is a side effect of spherical aberration of the exit pupil. It's explained on pages 182-183 of Rutten & van Venrooij "Telescope Optics" using the original 13mm Nagler eyepiece as an example...
Forum: Kowa Tuesday 15th January 2019, 13:34
Replies: 4
Views: 268
Posted By henry link
I guess I'll get my hopes up once again that this...

I guess I'll get my hopes up once again that this means a replacement for the TSN-88 scopes. Not that there is anything really wrong with the current big Kowas, which is a tribute their excellent 14...
Forum: Binoculars Monday 14th January 2019, 18:32
Replies: 41
Views: 1,349
Posted By henry link
As I recall it also assumes a scotopic light...

As I recall it also assumes a scotopic light level. At photopic levels I believe the claimed gain in detail is only 10%.

It's an easy enough thing to check with any binocular and a USAF 1951...
Forum: Tripod and Heads Friday 11th January 2019, 19:26
Replies: 4
Views: 175
Posted By henry link
What sort of grease are you two using? I have a...

What sort of grease are you two using? I have a 1720 with tilt movements that have always been too loose and floppy.
Forum: Spotting Scopes & tripod/heads Thursday 10th January 2019, 15:30
Replies: 2
Views: 277
Posted By henry link
I can answer a couple of your questions. The gray...

I can answer a couple of your questions. The gray Zeiss Diascope is an old model. It was made by Meopta and like many older Meopta products it has coatings that give its image a yellow color bias. In...
Forum: Spotting Scopes & tripod/heads Wednesday 9th January 2019, 15:56
Replies: 3
Views: 270
Posted By henry link
Hi lucznik, Keep in mind that the two flat...

Hi lucznik,

Keep in mind that the two flat mirrors used for folding don't act as an erecting system. Most of these scopes seem to use the same lens erecting system/zoom eyepiece combination found in...
Forum: Binoculars Monday 7th January 2019, 13:47
Replies: 37
Views: 2,057
Posted By henry link
Hi Robert, Thanks for the information. There is...

Hi Robert,

Thanks for the information. There is one error that's easily corrected. Everywhere you have used the term Swarobright should read Swarotop. Swarobright is a dielectric mirror coating, not...
Forum: Binoculars Saturday 5th January 2019, 20:38
Replies: 37
Views: 2,057
Posted By henry link
Thanks Canip, Gijs and John, I think John's...

Thanks Canip, Gijs and John,

I think John's excellent research has put my questions and wrong guesses about early Swarovski coatings to rest and opened up a new mystery for me. I can understand the...
Forum: Binoculars Saturday 5th January 2019, 01:08
Replies: 37
Views: 2,057
Posted By henry link
Hi Canip, Transmax before T* would be a...

Hi Canip,

Transmax before T* would be a surprise. Maybe we can confirm your observation by comparing the reflection colors returning from your 1975 10x40 to my 1990 8x30. Tomorrow I'll try to...
Forum: Binoculars Friday 4th January 2019, 16:43
Replies: 37
Views: 2,057
Posted By henry link
I've found no convincing evidence that...

I've found no convincing evidence that multi-coating was available in any civilian commercial binocular before Zeiss introduced the first T* in 1978.
Forum: Binoculars Friday 4th January 2019, 15:37
Replies: 10
Views: 506
Posted By henry link
Believe it or not I don't think there is more to...

Believe it or not I don't think there is more to the story provided all three parameters are accurately measured. If something seems off for a particular binocular after measuring the eyelens it's...
Forum: Binoculars Friday 4th January 2019, 14:35
Replies: 37
Views: 2,057
Posted By henry link
Gijs, Do you recall how old the Habicht 7x42 with...

Gijs, Do you recall how old the Habicht 7x42 with 86% transmission was?

John, How did you determine that there was a significant increase in Habicht transmission in mid 2009?

My experience with...
Forum: Binoculars Wednesday 2nd January 2019, 15:04
Replies: 5
Views: 333
Posted By henry link
This particular binocular looks like a simple...

This particular binocular looks like a simple bottom of the line Japanese 7x35 from the 50s to the 70s, probably not much better or worse than many other similar ones. The FOV is very narrow and the...
Forum: Binoculars Wednesday 2nd January 2019, 14:57
Replies: 10
Views: 506
Posted By henry link
The diameter of the eyelens is determined by two...

The diameter of the eyelens is determined by two things: the apparent FOV and the eye relief. The eyelens needs to be wide enough for rays from its edges to meet at a point equal to the eye relief...
Forum: Binoculars Monday 31st December 2018, 13:21
Replies: 174
Views: 6,298
Posted By henry link
Thanks David and Ed. That certainly makes a lot...

Thanks David and Ed. That certainly makes a lot more sense.

So the reason for the division appears to be to give larger/lower magnification binoculars an even easier ride. The resolution of an 8x42...
Forum: Binoculars Sunday 30th December 2018, 18:45
Replies: 174
Views: 6,298
Posted By henry link
If posting the ISO 14133-2 Table 2 is a violation...

If posting the ISO 14133-2 Table 2 is a violation of copyright would a moderator please remove it. I'll try to make this post work without it. (This has been removed for the reasons Henry gave. Lee,...
Forum: Zeiss Friday 28th December 2018, 22:37
Replies: 23
Views: 886
Posted By henry link
I'm not sure why we can't seem to connect about...

I'm not sure why we can't seem to connect about this. Maybe somebody else can join in.

Does it help to say that on the USAF 1951 size and distance are interchangeable? There's no difference between...
Forum: Zeiss Friday 28th December 2018, 19:19
Replies: 23
Views: 886
Posted By henry link
Nothing much would be gained at any distance from...

Nothing much would be gained at any distance from boosting the size of the smallest resolved details beyond 70x for someone like me with eyesight acuity of 20/15, which is about average. I could...
Forum: Zeiss Friday 28th December 2018, 14:43
Replies: 23
Views: 886
Posted By henry link
Yes, there would be some practical benefit to...

Yes, there would be some practical benefit to boosting the size of the smallest resolved details for those with below average acuity, but that will come at the price of degraded brightness and...
Showing results 1 to 25 of 1000
 


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