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Why the lack of lower magnification compacts?

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#51 KennyJ

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Posted 26 March 2013 - 06:30 PM

On the disputed matter of daylight brightness, the sheer level of brightness here at 53 degrees north, on a late winter/ early spring morning, with the sun low in the sky is certainly more dazzling than any light I encountered in Fiji.

If anything , the lower sun is more likely to cause the eye pupils to become even more constricted than an overhead sun.

In any case,it's like anything else when you KNOW you're right.

What other reason could there possibly be for people to "claim to perceive a difference" if they can't ?

Kenny

#52 Lane

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Posted 26 March 2013 - 09:00 PM

Leupold Katmai 6x32 - Don't know if they qualify as compact by definition, but they are very small imo. I got these last year and really like using them, especially for hiking. I can hold them totally steady due to the 6 power magnification. The only issue I have with them is the same issue i have with a lot of binoculars, I wish they had made them a little longer and recessed the objective further to avoid picking up stray light. I solved this by creating rings out of wide double sided velcro that I can slide forward on the front when conditions warrant.

#53 hallelujah

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Posted 26 March 2013 - 11:44 PM

Leupold Katmai 6x32 - Don't know if they qualify as compact by definition, but they are very small imo.


I purchased the now discontinued Leupold 6x32 Katmai for my wife a few years ago.
She actually prefers binoculars with more magnification. (10x)

I really really liked the optics in the Nikon Prostaff Compact reverse Porro binoculars,
unfortunately they were too small in my hands & lighter than I wanted.

http://www.nikonspor...oStaff-8x25-...

http://www.amazon.co...?ie=UTF8&amp...

Stan

#54 Jae

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Posted 27 March 2013 - 07:04 AM

Stan,
I've like the optics on small Nikons for a long time, as they are incredibly sharp and these with aspheric lenses are probably even sharper than the ones I've used. It's too bad they seem to get knocked out of alignment so easily (couple of amazon reviews seem to support this). I think they got the top rankings in the '80's in a consumer report.

After many alignment issues, back to Nikon, etc., I later bought a mountaineer 8x25 which seems more sturdy but they are not made any more. I've dropped those a number of times and it's still held collimation. I have a 9x25 that I've taken apart to adjust the prisms and then drop some glue to hold it better in place.

#55 Jon Isaacs

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Posted 27 March 2013 - 01:04 PM

On the disputed matter of daylight brightness, the sheer level of brightness here at 53 degrees north, on a late winter/ early spring morning, with the sun low in the sky is certainly more dazzling than any light I encountered in Fiji.

If anything , the lower sun is more likely to cause the eye pupils to become even more constricted than an overhead sun.

In any case,it's like anything else when you KNOW you're right.

What other reason could there possibly be for people to "claim to perceive a difference" if they can't ?

Kenny


That must explain the sun-beaten faces I see when northerner's come to visit San Diego in the winter. :)

When the sun comes up, it would seem that is passing through the same amount of atmosphere anywhere in the world because it's on the horizon. From there, it only gets brighter.

Has anyone measured their entrance pupil when outside on a bright day? The papers suggest that 2mm-3mm is reasonable.

Jon

#56 Rich V.

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Posted 27 March 2013 - 01:55 PM

Has anyone measured their entrance pupil when outside on a bright day? The papers suggest that 2mm-3mm is reasonable.


In light of my failure to read the data correctly a couple of days ago, I measured my constricted pupils at approx. 2-2.5mms in bright light yesterday. This would indicate that under the brightest conditions, my 8x23s are still being stopped down by my eyes to the same effective aperture as my 8x30s; around 8x20.

Strangely, holding one bino to each eye and switching eyes as well, the Nikon 8x23AS binos seemed to portray an evenly illuminated light colored door a bit brighter than the 8x30EIIs. It seems my eyes were being fooled by the differences in AFOV; the compact illuminating less of my retina with 48° AFOV vs. the EIIs with a 70° AFOV.

This begs the question about AFOV Glenn is alluding to above; if the exit pupil contains all the light passing through the optical system, for a given effective aperture, it would seem that the light is concentrated on a smaller portion of the retina with the narrower AFOV bino while the wider bino would be spreading that same amount of light over a greater area, decreasing the light intensity per square area of retina. Wouldn't this be just like a flashlight with an adustable beam? The source has the same intensity but as the beam is widened, the intensity per square area is decreased.:question: This makes sense to me...

Rich

#57 Lane

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Posted 27 March 2013 - 03:17 PM

Leupold Katmai 6x32 - Don't know if they qualify as compact by definition, but they are very small imo.


I purchased the now discontinued Leupold 6x32 Katmai for my wife a few years ago.
She actually prefers binoculars with more magnification. (10x)

I really really liked the optics in the Nikon Prostaff Compact reverse Porro binoculars,
unfortunately they were too small in my hands & lighter than I wanted.

http://www.nikonspor...oStaff-8x25-...

http://www.amazon.co...?ie=UTF8&amp...

Stan


They may be discontinued by the manufacturer but they are still available new from some locations and I believe they are sold with different brand names on them besides Leupold. Hard to beat that 8.1 degree field of view or the ultra close focus. I use them to watch butterflies and spiders sometimes. The 5mm exit pupil means they also work well as it is getting dark especially under heavy tree cover.

#58 GlennLeDrew

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Posted 27 March 2013 - 03:21 PM

Rich,
Other things being equal, a larger AFoV only illuminates more retina. The surface brightness is unchanged. This means the total illumination is greater because of the larger surface area of the retina illuminated.

And so in spite ofidentical surface brightness, I was positing the notion that the higher total brightness of the larger AFoV *might* lead to an impression of higher surface brightness.

Another possibility, competing against that just mentioned. A larger AFoV, by delivering higher total brightness, *might* result in a slightly more constricted pupil than will a smaller AFoV, in spite of identical surface brightness. This would then result in a slightly dimmer image.

The vagaries of the human visual system make for a potentially complex analysis of optical performance among instruments.

#59 smart

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Posted 28 March 2013 - 09:04 AM

Glenn, (RE: vagaries of the human eye.....): This is one of the most concise and meaningful statements concerning optical qualities that I've ever heard! Well said! :bow:






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