Observing Strategies for Maximising Light Reception for Astronomers with Aging Eyesight

[OzEclipse]

Hi All,
I have been working on this article for the past few weeks.

It first explains what happens to our eyesight as we age. It does not cover specific diseases of the eye, rather it covers unavoidable physiological changes that affect every person as they age, namely restriction of maximum pupil dilation.

Then I explain how this results in the poor transmission of light from eyepiece to the pupil of aging astronomers due to mismatch of the exit pupil of the telescope and the dilated pupil of the observer. Finally I present some strategies to maximise light transmission and deliver the brightest image to the observers' eye.

Telescope Exit Pupils and Aging Eyes.pdf

(3.75 MiB) Downloaded 53 times

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Regards

[jrkirkham]

Thanks for posting the interesting article. It is a problem we all face.

[Graeme1858]

Good article Joe.

Thanks for posting, from this ageing astronomer!

[OzEclipse]

It's best to determine your own exact dilation.
This can be done with the drill test described in the article.
In recent days, I have cut a wedge out of thin cardboard. This was very easy to make and could be used in place of the drills to determine pupil dilation.

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Here is another way to present the eyepiece focal length results of the paper that is a bit easier to read.
Along the horizontal axis is age and/or personal pupil dilation. The different lines represent scopes of various ƒ ratios from ƒ3 - ƒ10.

Read up from your age or better yet from your exact measured pupil dilation until you cross the line corresponding to your scope ƒ ratios.
Read across and this is the longest eyepiece focal length that you can use that gives 100% light transmission to the eye. You can use longer eyepieces but your eye progressively receives smaller percentages of the light exiting the telescope.

[helicon]

Good information Joe. Thanks!

[messier 111]

I did a quick overview and I quickly noticed a very research work.
I will read it when I get back from vacation . thx Joe .

[OzEclipse]

I had two friends staying for the weekend. We all used the wedge shown in a previous reply to this thread to measure our respective pupil dilations.

All three of us are aged between 58 and 62. All three of us registered dilations of 4.8 +/- 0.1mm in our dominant eye. I registered 4.8mm in my right dominant eye and 5mm in my left non-dominant eye. The others were symmetrical in both eyes. A few weeks ago, I registered 4.8 in my right eye using a drill test.

Last week, another friend, aged 82, and and observer of 60+ years experience, registered 4.0mm using the drill test.

I have friends from Sydney, Melbourne and Canberra coming to stay late September to observe comet Tsuchinan. I’m going to get each of them to do the wedge test and build up a small study of my own.

Joe.

[helicon]

Very interesting result of your effort. Also, neat upgrade to your avatar Joe!

[OzEclipse]

Very interesting result of your effort. Also, neat upgrade to your avatar Joe!

Hi Michael,
I created the new avatar to celebrate my"coronation."

[DeanD]

Thanks "King" Joe: nicely explained for all levels of experience. A bit depressing though!

Looks like I have done the right thing with 25mm plossls and 18mm Radians for my new 14" f5 binos. The Radians in particular with 3.6mm exit pupil should be good for another 20-30 years of viewing...

My 50mm plossl with the 60mm eye relief always was a bit of a worry!

Keep up the good work.

Dean