Return to the Cloudy Nights Telescope Reviews home pageAstronomics discounts for Cloudy Nights members
Get a Cloudy Nights T-Shirt Submit a Review / Article

Click here if you are having trouble logging into the forums

Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu uh, User

Equipment Discussions >> Binoculars

Pages: 1 | 2 | 3 | (show all)
John Kuraoka
sage
*****

Reged: 12/12/12

Loc: Sunny San Diego, CA
Re: Why the lack of lower magnification compacts? new [Re: Mark9473]
      #5757784 - 03/26/13 09:45 AM

To get back to the OP, I think, yes, marketing is partly to blame for the paucity of low-power binoculars. But other significant factors may be the decline in the mass popularity of live theater (remember when these 3-6x binoculars were called "opera glasses?") and the increasing size of sporting and entertainment venues.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Rich V.
Post Laureate
*****

Reged: 01/02/05

Loc: Lake Tahoe area, Nevada, USA
Re: Why the lack of lower magnification compacts? new [Re: Mark9473]
      #5757926 - 03/26/13 10:47 AM

Tests show that the constricted eye pupil during daytime hours may not be as small as some are suggesting; data shows people under 30 yrs. old in particular may only constrict to between 3 and 4mms. As we age, our pupil sizes tend to get smaller; both dilated and constricted. There appears to be a wide range of minimum eye pupil.

http://humanfactors.arc.nasa.gov/publications/watson_formula_pupilsize.pdf

See fig. 9

http://www.ncbi.nlm.nih.gov/pubmed/22179219

If this is the case, then the daytime difference in brightness between an 8x20 and an 8x42 could be easily apparent to many people as Kenny and Mark are suggesting.

Rich


Post Extras: Print Post   Remind Me!   Notify Moderator  
Tamiji Homma
Carpal Tunnel
*****

Reged: 02/24/07

Loc: California, USA
Re: Why the lack of lower magnification compacts? new [Re: Rich V.]
      #5757957 - 03/26/13 11:06 AM

Hi Rich,

Isn't it easy to use aperture mask to verify it for given instrument?

I can see big difference in brightness between 100mm f/4 (4.25mm exit pupil, using 17mm eyepiece) and 50mm (2.125mm) with aperture mask under daylight.

Is it valid experiment?

Tammy


Post Extras: Print Post   Remind Me!   Notify Moderator  
Rich V.
Post Laureate
*****

Reged: 01/02/05

Loc: Lake Tahoe area, Nevada, USA
Re: Why the lack of lower magnification compacts? new [Re: Tamiji Homma]
      #5758084 - 03/26/13 12:16 PM

Sure, Tammy, it would be easy enough to experiment with a set of masks to make comparisons. Our eyes don't perceive brightness in a linear way, though, so it's hard to say what a "big difference" may be.

In your example, you have a 4:1 brightness ratio that should be quite apparent. Going from a 4.25mm to a 3mm exit pupil would give you a 2:1 ratio; I wonder how easily many people could perceive that difference?

We also have to consider that a masked binocular will most likely provide a better illuminated exit pupil than an unmasked one. An 8x42 masked to 20mm could appear brighter than a native 8x20 binocular that has considerable falloff in illumination levels towards the edge of field.

Rich


Post Extras: Print Post   Remind Me!   Notify Moderator  
planetmalc
sage


Reged: 10/21/09

Re: Why the lack of lower magnification compacts? new [Re: holger_merlitz]
      #5758235 - 03/26/13 01:19 PM

Quote:

Last year I found a used Leitz 6x24 Trinovid of the 1960s, field of view: 212m/1000m, just amazing. Of course, coating technology was poor and the binocular is lacking brightness and contrast. I would like to have a modern version of that.

Cheers,
Holger




Exactly my sentiments. I have the earlier Amplivid (same real FOV) and it is a delight to use as long as the viewer doesn't get obsessed with the shortcomings you mention. Its nicest feature has to be the viewing comfort at the eye end; all other true compacts have small-diameter eyecups that make extended viewing sessions something of a trial, but the 6 x 24 Amplivid (and presumably the Trinovid also) have large-diameter eyecups of the kind you'd find on standard 30/32mm models, so viewing comfort is never a problem. There is something almost Tardis-like about looking through such a small glass and seeing a 70+ degree AFOV! Members who are serious about acquiring a low-power true compact should have this 6 x 24 right at the top of their list.

The Russian 5 x 25 roof prism is another model with sensibly-sized eyecups, and in some ways it gives better images than the Amplivid (though the AFOV is only around 60 degrees), but it's large and heavy for a 25mm binocular.

The tiny flat-pack Minolta 6 x 18UC, with its wide-ish rectangular field of view is another one to look out for as it addresses most of the optical shortcomings of the Amplivid/Trinovid, but comfortable-at-the-eye-end it ain't!

Edited by planetmalc (03/26/13 01:21 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Why the lack of lower magnification compacts? new [Re: Mark9473]
      #5758239 - 03/26/13 01:20 PM

Quote:

I hope a very bright winter morning is OK too?
Anyway I've just done your test with my Leica 8x20 and Vixen 8x42 and can re-confirm once more that for me the image in the 8x42 is brighter.




I suspect that a "winter morning from 51 degrees north" may be quite different thin terms of brightness than a spring afternoon on a sunny day from 32 degrees north...

Jon


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Why the lack of lower magnification compacts? new [Re: Rich V.]
      #5758313 - 03/26/13 02:07 PM

Quote:

Tests show that the constricted eye pupil during daytime hours may not be as small as some are suggesting; data shows people under 30 yrs. old in particular may only constrict to between 3 and 4mms. As we age, our pupil sizes tend to get smaller; both dilated and constricted. There appears to be a wide range of minimum eye pupil.

http://humanfactors.arc.nasa.gov/publications/watson_formula_pupilsize.pdf

See fig. 9

http://www.ncbi.nlm.nih.gov/pubmed/22179219

If this is the case, then the daytime difference in brightness between an 8x20 and an 8x42 could be easily apparent to many people as Kenny and Mark are suggesting.

Rich




Rich:

The Wikipedia article on Daylight is relevant in order to relate the measurement and models to daylight illumination levels. The one article uses Candlera per meter squared, this is the same unit as a Lux.

According the Daylight article in Wikipedia, the brightest sun is can be 120,000 lux, a blue sky illuminating the shade will be about 20,000 lux.

Looking at the data and modeling in the first paper, there is quite a range of pupil diameters but there is no data past or modeling past 10,000 lux and almost all of it seems to converge towards something well under 3mm and sometimes under 2mm. Figure 16 shows all the data in two graphs.

The way I read the second link, these tests were conducted at a uniform illumination level of 400 lux. According to Wikipedia, that is the equivalent of "Sunrise or sunset on a clear day (ambient illumination)." It's no surprise that exit pupils were on the order of 4mm.

Jon Isaacs


Post Extras: Print Post   Remind Me!   Notify Moderator  
Tamiji Homma
Carpal Tunnel
*****

Reged: 02/24/07

Loc: California, USA
Re: Why the lack of lower magnification compacts? new [Re: Rich V.]
      #5758361 - 03/26/13 02:39 PM

Quote:

In your example, you have a 4:1 brightness ratio that should be quite apparent. Going from a 4.25mm to a 3mm exit pupil would give you a 2:1 ratio; I wonder how easily many people could perceive that difference?




Hi Rich,

I thought that discussion started for 8x20 v.s. 8x42 during bright daytime use.
That's why I used 100mm v.s. 50mm aperture example.

I just went out backyard and tried 100mm/50mm comparison against bright sunny California blue sky. Brightness difference is big and obvious to me.

I can try different aperture mask weekend.

Tammy


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark9473
Postmaster
*****

Reged: 07/21/05

Loc: 51N 4E
Re: Why the lack of lower magnification compacts? new [Re: Jon Isaacs]
      #5758452 - 03/26/13 03:26 PM

Quote:

I suspect that a "winter morning from 51 degrees north" may be quite different thin terms of brightness than a spring afternoon on a sunny day from 32 degrees north...

Jon



How can you drag that kind of statement into this discussion. My God, will you not even believe that it was bright and sunny here?


Post Extras: Print Post   Remind Me!   Notify Moderator  
GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Why the lack of lower magnification compacts? new [Re: Mark9473]
      #5758514 - 03/26/13 03:48 PM

When doing the side-by-side, simultaneous test for binocular brightness using *separate* binos (or monoculars), remember to swap. Each eye can have a different pupil diameter, and even if identical, there can still be a difference in perceived brightness between each eye.

Other instrumental factors which can confound results:

- Differing system transmission.
- Differing AFoV, which alters total illumination.
- Differing exit pupil illumination characteristics.

Better to start with a large exit pupil bino and mask one side down. For then the instrumental variables are eliminated, except possibly for exit pupil illumination (where, at maximum, efficiency is a bit less; but this may be of concern only for BK-7 prism binos.)


Post Extras: Print Post   Remind Me!   Notify Moderator  
KennyJ
The British Flash
*****

Reged: 04/27/03

Loc: Lancashire UK
Re: Why the lack of lower magnification compacts? new [Re: GlennLeDrew]
      #5758931 - 03/26/13 07:30 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


Post Extras: Print Post   Remind Me!   Notify Moderator  
Lane
Post Laureate


Reged: 11/19/07

Loc: Frisco, Texas
Re: Why the lack of lower magnification compacts? new [Re: Jon Isaacs]
      #5759259 - 03/26/13 10:00 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.

Edited by Lane (03/26/13 10:04 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
hallelujah
Post Laureate
*****

Reged: 07/14/06

Loc: North Star over Colorado
Re: Why the lack of lower magnification compacts? [Re: Lane]
      #5759466 - 03/27/13 12:44 AM

Quote:

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.nikonsportoptics.com/Nikon-Products/Binoculars/7483/ProStaff-8x25-...

http://www.amazon.com/gp/offer-listing/B0007M6GEK/ref=dp_olp_used?ie=UTF8&...

Stan

Edited by hallelujah (03/27/13 01:00 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jae
Pooh-Bah
*****

Reged: 04/13/06

Loc: New England
Re: Why the lack of lower magnification compacts? new [Re: hallelujah]
      #5759702 - 03/27/13 08:04 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.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Why the lack of lower magnification compacts? new [Re: KennyJ]
      #5760413 - 03/27/13 02:04 PM

Quote:

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


Post Extras: Print Post   Remind Me!   Notify Moderator  
Rich V.
Post Laureate
*****

Reged: 01/02/05

Loc: Lake Tahoe area, Nevada, USA
Re: Why the lack of lower magnification compacts? new [Re: Jon Isaacs]
      #5760543 - 03/27/13 02:55 PM

Quote:

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. This makes sense to me...

Rich

Edited by Rich V. (03/27/13 03:14 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Lane
Post Laureate


Reged: 11/19/07

Loc: Frisco, Texas
Re: Why the lack of lower magnification compacts? new [Re: hallelujah]
      #5760711 - 03/27/13 04:17 PM

Quote:

Quote:

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.nikonsportoptics.com/Nikon-Products/Binoculars/7483/ProStaff-8x25-...

http://www.amazon.com/gp/offer-listing/B0007M6GEK/ref=dp_olp_used?ie=UTF8&...

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.


Post Extras: Print Post   Remind Me!   Notify Moderator  
GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Why the lack of lower magnification compacts? new [Re: Rich V.]
      #5760722 - 03/27/13 04:21 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.


Post Extras: Print Post   Remind Me!   Notify Moderator  
smart
member
*****

Reged: 07/28/07

Loc: Oregon coast
Re: Why the lack of lower magnification compacts? new [Re: GlennLeDrew]
      #5762086 - 03/28/13 10:04 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!

Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1 | 2 | 3 | (show all)


Extra information
7 registered and 16 anonymous users are browsing this forum.

Moderator:  Knuklhdastrnmr, WOBentley 

Print Thread

Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled


Thread views: 2712

Jump to

CN Forums Home


Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics