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Is it me, my eyes, or what? (1 Viewer)

adhoc

Well-known member
Binastro, I tried Googling.

Australians. I got to this, no closer to the source, but it should do I think. [Link]

Namibians. Sorry if this is silly of me but could you be mistaken by having read just the headline of this? It has to do with psychology and not visual acuity. [Link].
 

Binastro

Well-known member
Thanks adhoc,
I think you are right about the Namibian tribes.

I recall reading long ago that some hunting tribes in Africa have exceptional eyesight, but this does not seem to be a reference to that.

By the way, what eyesight test charts do Greeks, Russians, Chinese, Japanese, Arabic speakers and Thais use?
They may not know our letters well.
It may be that some people with exceptional eyesight don't read or write at all.
Women were not taught to read or write, and they may have excellent eyesight. How would one test them?

Our very good builder unfortunately couldn't read or write.
He used to drive a Reliant Robin 3 wheeler as he passed a motorcycle test in the army. He couldn't take a normal car test.
Maybe Del Boy had one.
This Reliant Robin got hit by someone jumping a red light. The Reliant just disintegrated. I think it was glass fibre. He was O.K. but shocked.
 
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typo

Well-known member
The anecdotal reports of the visual prowess of native Australians date back centuries, and through the last century some exceptional results have been recorded. In most cases where was little recorded about the actual details of the examination and the validity of some of the data has been questioned. I haven't been able to access Taylor's original thesis, but i understand from cited reports that he also found Caucasians in that study who's acuity also exceeded from Nyquist limit (from anatomical studies). This seems at odds with numerous other laboratory base studies. I've not found any satisfactory explaination. Unfortunately the visual health of the native Australian population is currently a grave concern, and much of Taylor's later work investigates visual impairment rather than prowess in this population.

David
 

adhoc

Well-known member
Binastro, Googling (what did I know before I could do that? :) for "visual acuity chart ___" substituting "Greek" etc. for "___" brings interesting results. A Chinese chart that may initially look strange to some is explained (I copy): "...Chinese is read from top to bottom and from right to left. Chinese patients may find one of the two versions easier to read as the characters on that chart are placed in vertical columns with increase in character size from right to left."
 

paddy7

Well-known member
Regarding tribal cultures and eyesight: perhaps those still living their traditional lifestyles, probably under little artificial light, in wide spaces, attuned to hunting or detection of danger, with no computers, close text etc. do not suffer the eyesight-limiting influences that we do.
Without descending into geo-politics, i would imagine the recent health problems experienced by Aborigines in Australia are more a consequence of what has happened more recently regarding their traditional lifestyles.
 

typo

Well-known member
Thanks David - very clear explanation, which in the development of this thread, probably needed reiteration.
I suppose that the only grit in the vaseline is the fact that the stray light issues (which the stopping-down is intended to prevent) will re-present themselves when the binocular is in general use in the field (i.e. not stopped-down).
Thus these manufacturing issues may prevent the high-performing, resolution-tested set from duplicating this in the birding environment.
Perhaps one with a better build quality and more care taken to QC issues, but performing slightly less well on the stopping down test, may thus be 'better' (if that is the word....)
Anyway, very appreciative of the concise revision of this issue.
thanks

Paddy,

Clearly, effective resolution is not everyone's first priority. Colour, contrast, brightness (luminance) CA, aberration and ergonomics all need to be factored in. On the other hand, wouldn't you would be disappointed if you bought a Ferarri and found it wasn't as fast as the family Toyota?

David
 

typo

Well-known member
Regarding tribal cultures and eyesight: perhaps those still living their traditional lifestyles, probably under little artificial light, in wide spaces, attuned to hunting or detection of danger, with no computers, close text etc. do not suffer the eyesight-limiting influences that we do.
Without descending into geo-politics, i would imagine the recent health problems experienced by Aborigines in Australia are more a consequence of what has happened more recently regarding their traditional lifestyles.

Some have suggested the demands of the traditional lifestyle might have made some evolutionary physiological differences, but so far I've found no evidence to support it. Unfortunately diseases such as diabetes and trachoma which are a particular visual heath concerns can be linked to much more recent changes in lifestyle.

David
 

Maljunulo

Well-known member
Paddy,

Clearly, effective resolution is not everyone's first priority.

David

If you can't see the bird well enough to ID it and it is just a bird-shaped blob, what good are your optics? (or any other-shaped blob)

Resolution up to your own limit would seem to me to be of primary importance.
 

paddy7

Well-known member
Paddy,

Clearly, effective resolution is not everyone's first priority. Colour, contrast, brightness (luminance) CA, aberration and ergonomics all need to be factored in. On the other hand, wouldn't you would be disappointed if you bought a Ferarri and found it wasn't as fast as the family Toyota?

David

Funny you should mention that, as just this morning, i tore past a Ferrari in my Toyota RAV4! However, it was parked.....
 

WJC

Well-known member
If you can't see the bird well enough to ID it and it is just a bird-shaped blob, what good are your optics? (or any other-shaped blob)

Resolution up to your own limit would seem to me to be of primary importance.

Hi, Richard:

Your point would be nearly beyond reproach if everyone’s wants and needs were focused on serious birding. But, they are not. For some, it’s the lack of chromatic aberration. For others, it’s a super-wide field of view, even if 40% of that field is crappy. Still, others demand a bino that weighs no more than a handful of postage stamps. Not only do our physiological abilities differ, our desires do as well and not all relate to sheer optical performance.

Finally, I haven’t seen much of you lately; are you well? I am rapidly learning that this getting older stuff is not for sissies! :cat:

Bill
 

Maljunulo

Well-known member
Hi, Richard:

Your point would be nearly beyond reproach if everyone’s wants and needs were focused on serious birding. But, they are not. For some, it’s the lack of chromatic aberration. For others, it’s a super-wide field of view, even if 40% of that field is crappy. Still, others demand a bino that weighs no more than a handful of postage stamps. Not only do our physiological abilities differ, our desires do as well and not all relate to sheer optical performance.

Finally, I haven’t seen much of you lately; are you well? I am rapidly learning that this getting older stuff is not for sissies! :cat:

Bill

Yes, thank you Bill.

A bird was only an example for a general statement. Empty magnification and an optic which simply shows a bigger blob is not my idea of a good optic.

Your point is well taken, however.

Cheers!
R
 

adhoc

Well-known member
So it seems that the title of the BBC item 'The astonishing vision and focus of Namibia's nomads' which has to do with psychology might mislead people to think that it is about visual acuity. See above at #40-42, here (again) is the [link]. But I wonder: With the more "straight"/"un-influenceable" vision described there do they see differently than we others (I am not one of them, "Anon." at left is not in Namibia!) the images in binoculars that are "corrected" for the various distortions? When rectilinear distortion is balanced by adding angular magnification distortion, etc., we (most of us others) see a more "natural" or satisfying image, but do they see a variety of weirdness?
 

typo

Well-known member
Resolution up to your own limit would seem to me to be of primary importance.

Exactly. The key point being, for some users that limit will be more than twice that of others. Some can readily spot the effective resolution differences between binoculars. Others clearly cannot.

David
 

paddy7

Well-known member
Without having seen the item in question, i wonder if we're talking about what happens on the brain side of the eye, rather than the eye itself - some value of enormous concentration, undistracted, perhaps? The way the cat family will fix on prey - both eyes bolted on, while the body prepares itself to strike...
 

typo

Well-known member
Without having seen the item in question, i wonder if we're talking about what happens on the brain side of the eye, rather than the eye itself - some value of enormous concentration, undistracted, perhaps? The way the cat family will fix on prey - both eyes bolted on, while the body prepares itself to strike...

Now you are talking psychology. Mind bending stuff.:-O

As far as I am able to understand the literature, the brain plays a major role for all of us, constantly shifting the area of interest, and the speed and level of detail interpretation. When we are simply alert and looking for a movement perhaps it works at the equivalent of a high frame rate and low resolution camera. Once a target is spotted the frame rate slows by something like a factor of 4, the area of interest reduced and the resolution increases by 5 to 10 fold. It is quite likely that this shift is more pronounced in a hunting community as it is in some elite sportsmen and women. Young native Australians are reported to have fewer refractive errors than their caucasian equivalent, but acuity beyond the Nyquist limit is a bit of a puzzle at present it seems.

David
 
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Colin

Axeman (Retired)
England
I agree James and when I was interviewing Milos Slany from Meopta and we were discussing the usefulness or otherwise of testing binoculars with them stopped-down, his closing remark was that testing at full aperture especially in twilight conditions is very revealing of binocular performance.

Lee

I agree to you both. A cheapo pair of bins used on a grey day will reveal a grey mush of a view whereas a top quality pair will almost seem that the sun is shining. Finding the price point where the improvement in quality is hardly noticable can save a lot of money. E.g., a pair costing £2000 will not be twice as good as one costing £1000.
 

Troubador

Moderator
Staff member
Supporter
When we are simply alert and looking for a movement perhaps it works at the equivalent of a high frame rate and low resolution camera. Once a target is spotted the frame rate slows by something like a factor of 4, the area of interest reduced and the resolution increases by 5 to 10 fold.

David

This is very close to my experience when scanning over complex tangles of rocks, skerries, islets in the sea when searching for Otters and I have described it elsewhere in very close to these terms. I have to deliberately slow down the 'frame rate' to be sure of spotting Otters which are wonderfully camouflaged if among the brown seaweeds. Scanning at the normal rate I simply don't see them unless they move or create disturbances in the water.

Lee
 
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stiv674

Active member
This is very close to my experience when scanning overcomplex tangles of rocks, skerries, islets in the sea when searching for Otters and I have described it elsewhere in very close to these terms. I have to deliberately slow down the 'frame rate' to be sure of spotting Otters which are wonderfully camouflaged if among the brown seaweeds. Scanning at the normal rate I simply don't see them unless they move or create disturbances in the water.

Lee

I've just spent the last two hours or so scanning for Otters... not very successfully I might add.

Perhaps I need better binoculars, or eyes ;)
 

Troubador

Moderator
Staff member
Supporter
I've just spent the last two hours or so scanning for Otters... not very successfully I might add.

Perhaps I need better binoculars, or eyes ;)

Stiv

My Otter-Spotting is done in the islands off the west coast of Scotland where they forage in the sea during the day. Down where you are I would expect they are mainly nocturnal apart from a few places like nature reserves where they get used to human activities.

Lee
 

stiv674

Active member
Stiv

My Otter-Spotting is done in the islands off the west coast of Scotland where they forage in the sea during the day. Down where you are I would expect they are mainly nocturnal apart from a few places like nature reserves where they get used to human activities.

Lee

Hi Lee

I'm actually on Mull this week, so similar to your usual locations. I have had a few sightings of them in the sea just off shore but only a brief glimpse of one fully out of the water...

Plenty of sea birds though!

Steve
 
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