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ZEISS DTI thermal imaging cameras. For more discoveries at night, and during the day.

Aging eyes (1 Viewer)

I would imagine (although have not investigated) that - as eyes age - perhaps the speed at which dilation/contraction occurs reduces, purely just as a muscle function.
In birding conditions, the light generally fades, rather than 'switches off'; same at sunrise, giving the pupils a little more or little less light gradually.
When i used to do more walking at night out on marshes, it took a while to get my night-sight, and i knew enough about it to not look towards any light sources, as it seemed to set me back for quite a while. It seemed that contraction happened faster than dilation, but this might be just my perception.
Contraction may be a defence mechanism, perhaps....
Good job cats don't use binoculars!
https://www.youtube.com/watch?v=i1znmh8d7U4
 
paddy7 said:
It seemed that contraction happened faster than dilation, but this might be just my perception.
Contraction may be a defence mechanism, perhaps....
Good job cats don't use binoculars!
https://www.youtube.com/watch?v=i1znmh8d7U4
Click to expand...

I have had the same experience. When I used to observe with a large reflector til the wee hours of the morning, we used red flashlights to look at charts and fill out our logbooks, and any other light source besides the stars and the moon were considered a terrible intrusion into our 'adaptation' to low light, i.e. dilation. If any cars or other 'gross' light bearing objects came near, we shut our eyes, and sometimes retreated to a position to maintain our night vision. The pupil shuts down quickly, and takes awhile to fully open up again.
 
Dark adaptation has very little to do with the size of a person's pupil, and everything to do with chemical effects at the retina.
Even a change from 2mm to 7mm pupils is only a factor of 12.

However, the fully dark adapted eye has large gains from the chemical changes.

In fact a very short period of non intense white light, say a second, has little effect on dark adapted eyes.

The chemical changes take at least half an hour even for young people.
Being elderly I find this takes longer for me and is not as effective as when I was young.

Full dark adaptation takes at least a day.
Deep sky observers do not go out in sunshine the previous day.

In the book related to the movie 'Catch me if you can', Frank Abagnale Jr. describes being in total darkness for maybe 6 months in a French prison. When eventually released the guards only allowed him to see dim light for a long time, before gradually exposing him to full light.
He was maybe 18 or 19 years old.
His young eyes made use of the faintest glimmer of light.
He almost didn't survive the ordeal, which was meant as punishment, not so called rehabilitation.

In a case of a family hidden underground for a year in WW2 the experience of daylight was disturbing. I think everything appeared red to the survivors. It took quite a time to recover their sight.

Vitamin A I think is needed for good eyesight, maybe that is where the carrots come in.
 
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Further to post 63.
I have seen the planet Venus high in a blue summer sky in the middle of the day together with many school friends. It was very bright, maybe mag minus 4 or a bit brighter.
I have seen this many times as an adult also.
I have also seen Jupiter many times in the daytime with the Sun at less than 10 degree elevation, around magnitude minus 2.5.
All unaided eyes.
I think that the limit high in the daytime sky is about mag minus 3.

At night at say 50 degree elevation I could see stars of magnitude 6.5 to 6.7 in a dark sky.

So the difference with detectable 'stars' at night and daytime is about 9.5 mags or 6,000 times. If we say 9 mags then 4,000x.
As mentioned the pupil size difference is about 12x.

For extended objects, say a daylight comet, I think it would have to be mag minus 5 or mag minus 6 at least, compared to a detectable mag 5.5 comet in a dark sky.
Say 11 mags or 25,000 times difference.

It is difficult to be precise about the difference in detectable brightness between night fully dark adapted and daytime bright sunshine, but pupil size is only a small component.

The aging eyes do have problems of varying amounts from person to person.
 
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Great annual visit check up with my eye doctor. Vision (after cataract surgery) still 20\15 both eyes, no additional floaters, pressures and optic nerves all good. |:d|

Interestingly, my visits' medical dilation (mydriasis) yielded 8mm pupils, which he stated would be equal to "maximum long-exposure no-light acclimated dilation". When I inquired about visual low light adaptation, he said I could expect to achieve about 80% dilation of that during nightly extreme low-light exposures! Guess I couldn't fully use the 7.0mm EP of some bigger glass, but would be close! Think I'll just continue to enjoy the 10X50 SVs! :t:

Ted
 
Binastro has posted good info about dark adaptation. I would only add two thoughts.
  • First, while dark adaptation can take quite a while, the dilation part of adaptation happens in seconds to minutes. I don't know how that timing changes with age, but dilation is still relatively quick compared with other aspects of adaptation.
  • Second, I believe that the drug they use will open your pupil much wider than it would normally adapt in the dark. You could ask your optometrist or ophthalmologist, if there is a relationship between what you measure induced by the drops and your maximum dark adapted pupil.
 
ailevin said:
...I believe that the drug they use will open your pupil much wider than it would normally adapt in the dark. You could ask your optometrist or ophthalmologist, if there is a relationship between what you measure induced by the drops and your maximum dark adapted pupil.
Click to expand...

Yes. I did ask those questions of my eye doctor, an opthalmologist.

As per my post #65, he did affirm a direct and equal correlation of my medical evaluative dilation to a maximum dark adaptitive pupil (one that would take many hours of dark exposure, or even as Binastro stated in post 63, even a day)! Then, he qualified I could expect about 80% of that "mydriatic agent induced dilation" under a more normal, shorter term of very low light adaptation!

The drug you're speaking of might be the compound product used for eye surgical dilation, such as during my cataract lenses removal\replacement procedures. This sympathomimetic drug opens the pupil so wide, the Iris almost disappears.

Ted
 
Theo98 said:
Great annual visit check up with my eye doctor. Vision (after cataract surgery) still 20\15 both eyes, no additional floaters, pressures and optic nerves all good. |:d|

Interestingly, my visits' medical dilation (mydriasis) yielded 8mm pupils, which he stated would be equal to "maximum long-exposure no-light acclimated dilation". When I inquired about visual low light adaptation, he said I could expect to achieve about 80% dilation of that during nightly extreme low-light exposures! Guess I couldn't fully use the 7.0mm EP of some bigger glass, but would be close! Think I'll just continue to enjoy the 10X50 SVs! :t:

Ted
Click to expand...

Ted:

It is good of you to report your excellent checkup. Eyes are one thing that
are very important.

I had a full checkup recently, and was also pleased in my eye health.
My mother has the start of glaucoma, but has controlled it with proper
medication.

Also it was good of you to tell us how your dilation situation is.

I suspected such, we have too many experts on the site telling all of us here, that once we reach a certain age our eyes will only dilate so far.

Now we know that is bunk. ;) Enjoy those 10x50's, that size is very nice
in many ways. Now, you need a nice 8x56, as you can handle it..

Jerry
 
NDhunter said:
Ted:

It is good of you to report your excellent checkup. Eyes are one thing that
are very important...Also it was good of you to tell us how your dilation situation is.

Jerry
Click to expand...

Thanks Jerry,

My correction for over 50 years went from 20\400 to beyond 20\700 (Myopia)...it really is a blessing to be able to SEE!!! :bounce:

Ophthalmologist says when I'm exhumed in 200 years for a postmortem autopsy (who done it?)..., what's left will be my skeleton and my cataract replacement lenses! :cool:

As per optical performances and individual perceptions, my dilation capabilities certainly fall under the premise, "YMMV"! :t:

Ted
 
black crow said:
I get to look at some nice binoculars at many different price ranges. I have access to Kowa Genesis , Swarovski 8x50 and the mid priced guys like Zen Ray, Meopta Meopro, Eagle Optics, etc. You get the idea.

Really I don't see that much difference in them. I mean I do see a difference but sometimes it's really very small. I'm 65 years old and I'm thinking that's why I don't see that much difference. Do you guys think that's likely what is going on? I know my eyes are not what they were even five years ago. I used to have perfect vision but it's gone bye bye.

So... let's say that my old eyes are likely the issue. Then for someone with older eyes is it somewhat of a waste to pay for alpha binoculars when a $500 pair or less would be just about as good viewing as a $2300 pair.
Click to expand...
I've followed this thread with interest because of your perspective. I'm a very casual birder and backyard astronomy enthusiast, and recently bought a pair of bins I expect to be pretty good for the money. I do photography professionally and can't be casual there, but even there two principles come into play. One is diminished returns. If I spent ten times as much, would the product be better? Probably. Ten times better? Never. The other is a more obscure principle because I've only ever heard it expressed by myself. That's the idea that there are levels of expense and quality. Say you divide binoculars into rough thirds: cheap, mid-priced, fancy. If you're casual but care about value, the top end of cheap might work for you. If you're serious but on a budget, the top end of mid might be where you want to be. If you have the bucks, and want the best, go nuts. You'll still be arguing with your high-budget acquaintances about what's best but that's life. There are always compromises to be made but these ideas have helped me make decisions over the years, no matter how much money was jingling in my pocket.
 
I will be 87 years old in February and I had bilateral cataract surgery twelve years ago. I have worn sunglasses since because replacing my old, yellowed lenses has allowed my retinas to be flooded with light, to the point of being uncomfortable. The most startling result was the change in how far into the short end of the spectrum I could see. It was absolutely stunning.

As to binoculars, I recently purchased a pair of Zeiss SF 8X32 to replace my six-year-old Swarovski EL SV 10X42.

The Zeiss glasses are noticeably brighter and the images have a "crystalline" quality that the EL lack. I can only attribute this to six years progress in coatings, and probably different glass.I tend to think that the 0.2 mm difference in exit pupil size is insignificant. This is daytime observation only.

I guess my point here is that obviously in my case I am still capable of seeing differences in image brightness which according to numbers on paper would be "the same". Generalizing can be risky, because an exception always seems to pop up.

I'm not sure how this will be picked apart here, but I can only report what I see.
 
One point about aging eyes I don't think many consider is you need 3 times as much light as 60 as you do at 20 and your eyes on average are only going to dilate to 6 mm. So unless you know your pupils are dilating larger than 6 mm you are wasting your time and money buying a binocular with a 7 mm exit pupil like a 8x56 or 7x50. A binocular that has higher transmission but perhaps a smaller exit pupil in the range of 5 to 6 mm like a Swarovski Habicht 7x42 will have more apparent brightness than that big Swarovski SLC 8x56 for most people that are over 60 years of age. As you age transmission becomes more important than exit pupil because the cone of light reaching your eye is brighter and your eyes are not going to be able to dilate enough for a 7 mm cone of light. So a binocular with high transmission like a Zeiss HT 10x54 or Swarovski Habicht 7x42 is going to seem brighter than a SLC 8x56 even though they have a smaller exit pupil. It is something to think about if you are over 60 and you are buying a binocular for low light use.
 

​


Maljunulo,

It is good to see you again after a bit of a hiatus, and good for you for getting out with the new SF 8X32. At your age, I say congratulations first and secondly, enjoy the views with two great glass, the SV and the SF.

Andy W.
 
Andy:

Thank you so much for your kind words.

I think I will offer the EL SV to my #1 granddaughter that she may enjoy them for many years, and that they may even become an heirloom.

The SF 8X32 are just absolutely addictive.

Stay safe.
Richard
 
[email protected] said:
So unless you know your pupils are dilating larger than 6 mm you are wasting your time and money buying a binocular with a 7 mm exit pupil like a 8x56 or 7x50.
Click to expand...
Has anyone actually proved this is the case with real observations rather than theories? And that it only applies to older people? I would have thought that in low light conditions around dawn and dusk, one look at the brightening sky and anyone's pupils might shrink down again, no matter their age.

A friend and I compared my 8x40's with his 8x 50's (or something like that), and we couldn't tell the difference.
 
It seems to me that pupil dilation is perhaps easiest to assess and discuss, but that deteriorating eyesight, perhaps because of cataracts, astigmatism or other, is a more fundamental issue impacting observers. Even with glasses, many of us fall well short of 20/20 vision.
Will the small gains in optical performance achieved by the latest alphas even be perceptible for these individuals?
 
Probably not, but it sure is fun splitting hairs about it. People must be really bored - maybe they should go out more and actually look at the world through all those binos.
 
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