During last evening's SLAS meeting Prez. Dave covered basic telescope math including several mentions of various optical systems' exit pupils (basically diameter/power). During Advanced Training that followed I asked around about how to go about measuring the size of the eye's pupil. Dave and I both remembered the pupil measurement device Edmund used to sell but Dave noted it didn't do much good since it had to be used with the lights on. Anyone here have any ideas on how to measure pupil diameter under low-light conditions? Thanks, patrick p.s. As was noted in the meeting, Dave's talk was a historic first in that it was the first time he had ever given a presentation with a computer and *NO* slide projector. Could this possibly mean SLAS's aged and long suffering slide projector is now going to join the Mickey Mouse telescope in well deserved retirement?!?
I have used the following method to measure my pupil size: Set up a camera with a remote or cable release on a tripod in front of a mirror in a room that can be made completely dark. Focus the camera on your reflected image and prepare it to take a picture in the dark with the flash. (Beware not to use any redeye reduction pre-flash setting.) Turn out the lights and wait for your eyes to become completely dark adapted. Stand adjacent to the camera holding a subdivided millimeter scale next to your eye and take your picture. From the resulting image you can use the scale that you held by your eye to measure your fully dilated pupil size. Last time I did this I measured my pupil to be about 7.2 mm in diameter. Kim -----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Patrick Wiggins Sent: Wednesday, July 21, 2010 12:26 AM To: utah astronomy utah astronomy listserve Subject: [Utah-astronomy] Measuring pupil size During last evening's SLAS meeting Prez. Dave covered basic telescope math including several mentions of various optical systems' exit pupils (basically diameter/power). During Advanced Training that followed I asked around about how to go about measuring the size of the eye's pupil. Dave and I both remembered the pupil measurement device Edmund used to sell but Dave noted it didn't do much good since it had to be used with the lights on. Anyone here have any ideas on how to measure pupil diameter under low-light conditions? Thanks, patrick p.s. As was noted in the meeting, Dave's talk was a historic first in that it was the first time he had ever given a presentation with a computer and *NO* slide projector. Could this possibly mean SLAS's aged and long suffering slide projector is now going to join the Mickey Mouse telescope in well deserved retirement?!? _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php Visit the Wiki: http://www.utahastronomy.com
Ah, good idea. Maybe we could have a "pupil measuring session" during a star party at SPOC where instead of using a mirror we could go in the SPOC garage and have someone take pictures of those wishing to be measured. BTW, isn't 7.2mm a tad on the large size? patrick On 21 Jul 2010, at 01:37, Kim wrote:
I have used the following method to measure my pupil size: Set up a camera with a remote or cable release on a tripod in front of a mirror in a room that can be made completely dark. Focus the camera on your reflected image and prepare it to take a picture in the dark with the flash. (Beware not to use any redeye reduction pre-flash setting.) Turn out the lights and wait for your eyes to become completely dark adapted. Stand adjacent to the camera holding a subdivided millimeter scale next to your eye and take your picture. From the resulting image you can use the scale that you held by your eye to measure your fully dilated pupil size.
Last time I did this I measured my pupil to be about 7.2 mm in diameter.
Kim
I just tried it here at home, standing in front of the camera in the dark and triggering the exposure with the self-timer. The biggest problem was focus (sound familiar, fellow astro-imagers?). While I understand that it takes a long time to become fully dark adapted would it be safe to say that it only takes a few seconds for the pupil to expand to maximum size once exposed to dark? That's to say, once positioned in front of the camera is there any need to wait more than a few seconds after turning off the lights to take the picture? Carpe Noctem! patrick On 21 Jul 2010, at 01:49, Patrick Wiggins wrote:
Ah, good idea. Maybe we could have a "pupil measuring session" during a star party at SPOC where instead of using a mirror we could go in the SPOC garage and have someone take pictures of those wishing to be measured.
BTW, isn't 7.2mm a tad on the large size?
patrick
On 21 Jul 2010, at 01:37, Kim wrote:
I have used the following method to measure my pupil size: Set up a camera with a remote or cable release on a tripod in front of a mirror in a room that can be made completely dark. Focus the camera on your reflected image and prepare it to take a picture in the dark with the flash. (Beware not to use any redeye reduction pre-flash setting.) Turn out the lights and wait for your eyes to become completely dark adapted. Stand adjacent to the camera holding a subdivided millimeter scale next to your eye and take your picture. From the resulting image you can use the scale that you held by your eye to measure your fully dilated pupil size.
Last time I did this I measured my pupil to be about 7.2 mm in diameter.
Kim
Easiest way is to use a set of metric allen wrenches. While looking at a bright star in the dark, slowly wave an allen wrench back and forth. If the allen wrench is smaller than you eye's pupil you will see difraction effects from the light passing both sides of the wrench at the same time. Your pupil size will be between the largest wrench where you see the effect and the next largest size where you don't see it. This method is at least 20 years old, I have no idea where I first read about it. But you need to hold the wrench so the light passes the flat sides and not the edges so the width is the true size of the wrench. DT
Excellent idea Daniel. I'll give it a try. Thank you! patrick On 21 Jul 2010, at 04:39, daniel turner wrote:
Easiest way is to use a set of metric allen wrenches. While looking at a bright star in the dark, slowly wave an allen wrench back and forth. If the allen wrench is smaller than you eye's pupil you will see difraction effects from the light passing both sides of the wrench at the same time. Your pupil size will be between the largest wrench where you see the effect and the next largest size where you don't see it.
This method is at least 20 years old, I have no idea where I first read about it. But you need to hold the wrench so the light passes the flat sides and not the edges so the width is the true size of the wrench.
DT
Patrick, Since you threw down the gauntlet (whether intentionally or not), I've spent the last couple of hours determining my pupil size. Didn't think I could sleep anyway. I recall that the last time I tried this test years ago I used a mirror because I was using a film camera and didn't have a cable release that was long enough to simply direct the camera at my face for a self portrait. Tonight (this morning) I used my Nikon D70 digital camera, and of course it was much easier. I set up the camera to take a direct image of my face while holding a scale by my eye. I waited ten minutes after turning out the lights then shot the picture. I measured a pupil diameter of just under7mm.
From the age of about 12 I've tried to wear sunglasses whenever I am outdoors and this protection seems to have helped give me fairly good night vision. I double-checked my notes and the first time I did this pupil diameter test I actually had an 8mm pupil diameter. Wikipedia gives a range of between 5mm and 9mm for pupil size in young adults (http://en.wikipedia.org/wiki/Exit_pupil) so I don't think that 7.2mm or even 8mm is necessarily on the high side for my age at the time. You can see, however, that my age appears to be catching up with me.
Kim -----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Patrick Wiggins Sent: Wednesday, July 21, 2010 1:49 AM To: Utah Astronomy Subject: Re: [Utah-astronomy] Measuring pupil size Ah, good idea. Maybe we could have a "pupil measuring session" during a star party at SPOC where instead of using a mirror we could go in the SPOC garage and have someone take pictures of those wishing to be measured. BTW, isn't 7.2mm a tad on the large size? patrick On 21 Jul 2010, at 01:37, Kim wrote:
I have used the following method to measure my pupil size: Set up a camera with a remote or cable release on a tripod in front of a mirror in a room that can be made completely dark. Focus the camera on your reflected image and prepare it to take a picture in the dark with the flash. (Beware not to use any redeye reduction pre-flash setting.) Turn out the lights and wait for your eyes to become completely dark adapted. Stand adjacent to the camera holding a subdivided millimeter scale next to your eye and take your picture. From the resulting image you can use the scale that you held by your eye to measure your fully dilated pupil size.
Last time I did this I measured my pupil to be about 7.2 mm in diameter.
Kim
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BTW, I freaked out my wife when I set up the camera on a tripod in the bathroom in the middle of the night. I think she is still skeptical about what I was doing... Kim -----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Kim Sent: Wednesday, July 21, 2010 8:01 AM To: 'Utah Astronomy' Subject: Re: [Utah-astronomy] Measuring pupil size Patrick, Since you threw down the gauntlet (whether intentionally or not), I've spent the last couple of hours determining my pupil size. Didn't think I could sleep anyway. I recall that the last time I tried this test years ago I used a mirror because I was using a film camera and didn't have a cable release that was long enough to simply direct the camera at my face for a self portrait. Tonight (this morning) I used my Nikon D70 digital camera, and of course it was much easier. I set up the camera to take a direct image of my face while holding a scale by my eye. I waited ten minutes after turning out the lights then shot the picture. I measured a pupil diameter of just under7mm.
From the age of about 12 I've tried to wear sunglasses whenever I am outdoors and this protection seems to have helped give me fairly good night vision. I double-checked my notes and the first time I did this pupil diameter test I actually had an 8mm pupil diameter. Wikipedia gives a range of between 5mm and 9mm for pupil size in young adults (http://en.wikipedia.org/wiki/Exit_pupil) so I don't think that 7.2mm or even 8mm is necessarily on the high side for my age at the time. You can see, however, that my age appears to be catching up with me.
Kim -----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Patrick Wiggins Sent: Wednesday, July 21, 2010 1:49 AM To: Utah Astronomy Subject: Re: [Utah-astronomy] Measuring pupil size Ah, good idea. Maybe we could have a "pupil measuring session" during a star party at SPOC where instead of using a mirror we could go in the SPOC garage and have someone take pictures of those wishing to be measured. BTW, isn't 7.2mm a tad on the large size? patrick On 21 Jul 2010, at 01:37, Kim wrote:
I have used the following method to measure my pupil size: Set up a camera with a remote or cable release on a tripod in front of a mirror in a room that can be made completely dark. Focus the camera on your reflected image and prepare it to take a picture in the dark with the flash. (Beware not to use any redeye reduction pre-flash setting.) Turn out the lights and wait for your eyes to become completely dark adapted. Stand adjacent to the camera holding a subdivided millimeter scale next to your eye and take your picture. From the resulting image you can use the scale that you held by your eye to measure your fully dilated pupil size.
Last time I did this I measured my pupil to be about 7.2 mm in diameter.
Kim
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As a lot of you are probably aware there will be a full solar eclipse on May 20th 2012. The full disc eclipse is going to pass right through Glen Canyon National Recreation Area, almost directly over Horsehoe Bend right south of Page, AZ. We are already working with a number of other parks to set up events for the few days surrounding the eclipse. If anyone has any input or ideas or would like to join in we are really hoping to get a good turnout. Map http://eclipse.gsfc.nasa.gov/SEgoogle/SEgoogle2001/SE2012May20Agoogle.html Cheers, David
This is an annular eclipse so the Moon won't cover the Sun properly to allow viewing of the Corona. It will still be neat to look at but won't be as good as the one they had in the South Pacific this year. The next total eclipse in our area is in 2017. It is cutting right across the US including towns like Idaho Falls and Jackson WY. It is Monday, 21 Aug 2017. Dave -----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of David Rankin Sent: Wednesday, July 21, 2010 9:22 AM To: Utah Astronomy Subject: [Utah-astronomy] 2012 Solar Eclipse As a lot of you are probably aware there will be a full solar eclipse on May 20th 2012. The full disc eclipse is going to pass right through Glen Canyon National Recreation Area, almost directly over Horsehoe Bend right south of Page, AZ. We are already working with a number of other parks to set up events for the few days surrounding the eclipse. If anyone has any input or ideas or would like to join in we are really hoping to get a good turnout. Map http://eclipse.gsfc.nasa.gov/SEgoogle/SEgoogle2001/SE2012May20Agoogle.ht ml Cheers, David _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php Visit the Wiki: http://www.utahastronomy.com
Yea, I did read the moon was going to be to far away to fully cover the disc of the sun, but it will be awesome to see. I suspect a lot of people are going to be traveling to the area to see it. On 7/21/2010 8:52 AM, Dunn, David wrote:
This is an annular eclipse so the Moon won't cover the Sun properly to allow viewing of the Corona. It will still be neat to look at but won't be as good as the one they had in the South Pacific this year.
The next total eclipse in our area is in 2017. It is cutting right across the US including towns like Idaho Falls and Jackson WY. It is Monday, 21 Aug 2017.
Dave
-----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of David Rankin Sent: Wednesday, July 21, 2010 9:22 AM To: Utah Astronomy Subject: [Utah-astronomy] 2012 Solar Eclipse
As a lot of you are probably aware there will be a full solar eclipse on
May 20th 2012. The full disc eclipse is going to pass right through Glen
Canyon National Recreation Area, almost directly over Horsehoe Bend right south of Page, AZ.
We are already working with a number of other parks to set up events for
the few days surrounding the eclipse. If anyone has any input or ideas or would like to join in we are really hoping to get a good turnout.
Map
http://eclipse.gsfc.nasa.gov/SEgoogle/SEgoogle2001/SE2012May20Agoogle.ht ml
Cheers,
David
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Hi David, I'll second what David Dunn said here about the importance of being on (not near) the centerline during total and annular solar eclipses. To paraphrase David Bernson (a lot of Davids here) at last evening's SLAS meeting, being only near the centerline and not on it is like kissing a close relative. The folks at Bryce are in the same situation as Glen Canyon in that they are in the band of annularity but well off the centerline so the best either park can hope for is out of round annularity. Another challenge Glenn Canyon is up against is being further along the eclipse path which means annularity will occur lower in the sky than for sites further to the west. I've exchanged emails with a town official from Kanarraville. He is going to have a surveyor visit the part of his town where the centerline will cross and measure the local horizons. Hopefully that will show all of annularity will be visible from there. If not it means we'll need to do a bit of hiking up the hill above town to get a better view. Happily the event is still nearly two years out so we've plenty of time to prepare. Clear skies, patrick On 21 Jul 2010, at 09:21, David Rankin wrote:
As a lot of you are probably aware there will be a full solar eclipse on May 20th 2012. The full disc eclipse is going to pass right through Glen Canyon National Recreation Area, almost directly over Horsehoe Bend right south of Page, AZ.
We are already working with a number of other parks to set up events for the few days surrounding the eclipse. If anyone has any input or ideas or would like to join in we are really hoping to get a good turnout.
Map
http://eclipse.gsfc.nasa.gov/SEgoogle/SEgoogle2001/SE2012May20Agoogle.html
Cheers,
David
I second what Patrick said about the centerline. If we're not there, the ring will be lopsided. -- Joe --- On Wed, 7/21/10, Patrick Wiggins <paw@wirelessbeehive.com> wrote: From: Patrick Wiggins <paw@wirelessbeehive.com> Subject: Re: [Utah-astronomy] 2012 Solar Eclipse To: "Utah Astronomy" <utah-astronomy@mailman.xmission.com> Date: Wednesday, July 21, 2010, 10:30 PM Hi David, I'll second what David Dunn said here about the importance of being on (not near) the centerline during total and annular solar eclipses. To paraphrase David Bernson (a lot of Davids here) at last evening's SLAS meeting, being only near the centerline and not on it is like kissing a close relative. The folks at Bryce are in the same situation as Glen Canyon in that they are in the band of annularity but well off the centerline so the best either park can hope for is out of round annularity. Another challenge Glenn Canyon is up against is being further along the eclipse path which means annularity will occur lower in the sky than for sites further to the west. I've exchanged emails with a town official from Kanarraville. He is going to have a surveyor visit the part of his town where the centerline will cross and measure the local horizons. Hopefully that will show all of annularity will be visible from there. If not it means we'll need to do a bit of hiking up the hill above town to get a better view. Happily the event is still nearly two years out so we've plenty of time to prepare. Clear skies, patrick On 21 Jul 2010, at 09:21, David Rankin wrote:
As a lot of you are probably aware there will be a full solar eclipse on May 20th 2012. The full disc eclipse is going to pass right through Glen Canyon National Recreation Area, almost directly over Horsehoe Bend right south of Page, AZ.
We are already working with a number of other parks to set up events for the few days surrounding the eclipse. If anyone has any input or ideas or would like to join in we are really hoping to get a good turnout.
Map
http://eclipse.gsfc.nasa.gov/SEgoogle/SEgoogle2001/SE2012May20Agoogle.html
Cheers,
David
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Patrick, I'm a little confused. If you look at the map, the center line is passing hardly south of Page, AZ well within Glen Canyon NRA with plenty of time to see it....? http://www.slas.us/gallery2/main.php?g2_itemId=3587&g2_imageViewsIndex=1 That is a screen shot from the map. You can see Page, the center line of the eclipse, and Horse Shoe Bend right next to it? Anyway, we are in the process of planning events here. David On 7/21/2010 9:30 PM, Patrick Wiggins wrote:
Hi David,
I'll second what David Dunn said here about the importance of being on (not near) the centerline during total and annular solar eclipses. To paraphrase David Bernson (a lot of Davids here) at last evening's SLAS meeting, being only near the centerline and not on it is like kissing a close relative.
The folks at Bryce are in the same situation as Glen Canyon in that they are in the band of annularity but well off the centerline so the best either park can hope for is out of round annularity.
Another challenge Glenn Canyon is up against is being further along the eclipse path which means annularity will occur lower in the sky than for sites further to the west.
I've exchanged emails with a town official from Kanarraville. He is going to have a surveyor visit the part of his town where the centerline will cross and measure the local horizons. Hopefully that will show all of annularity will be visible from there. If not it means we'll need to do a bit of hiking up the hill above town to get a better view.
Happily the event is still nearly two years out so we've plenty of time to prepare.
Clear skies,
patrick
On 21 Jul 2010, at 09:21, David Rankin wrote:
As a lot of you are probably aware there will be a full solar eclipse on May 20th 2012. The full disc eclipse is going to pass right through Glen Canyon National Recreation Area, almost directly over Horsehoe Bend right south of Page, AZ.
We are already working with a number of other parks to set up events for the few days surrounding the eclipse. If anyone has any input or ideas or would like to join in we are really hoping to get a good turnout.
Map
http://eclipse.gsfc.nasa.gov/SEgoogle/SEgoogle2001/SE2012May20Agoogle.html
Cheers,
David
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Ah, that's good news. I misunderstood your site was north of Page. South of Page where your map shows the centerline crossing highway 89 will be fine as long as the horizon is no higher than 9 degrees. Clear skies! patrick On 21 Jul 2010, at 22:47, David Rankin wrote:
Patrick,
I'm a little confused. If you look at the map, the center line is passing hardly south of Page, AZ well within Glen Canyon NRA with plenty of time to see it....?
http://www.slas.us/gallery2/main.php?g2_itemId=3587&g2_imageViewsIndex=1
That is a screen shot from the map. You can see Page, the center line of the eclipse, and Horse Shoe Bend right next to it?
Anyway, we are in the process of planning events here.
David
So, say the weather actually cooperates and this happens. I can see we are in the last 10 minute interval before sunset and they are showing the eclipse ending in Texas. We will only have 9 degrees to work with? Thanks David On 7/21/2010 10:00 PM, Patrick Wiggins wrote:
Ah, that's good news. I misunderstood your site was north of Page.
South of Page where your map shows the centerline crossing highway 89 will be fine as long as the horizon is no higher than 9 degrees.
Clear skies!
patrick
On 21 Jul 2010, at 22:47, David Rankin wrote:
Patrick,
I'm a little confused. If you look at the map, the center line is passing hardly south of Page, AZ well within Glen Canyon NRA with plenty of time to see it....?
http://www.slas.us/gallery2/main.php?g2_itemId=3587&g2_imageViewsIndex=1
That is a screen shot from the map. You can see Page, the center line of the eclipse, and Horse Shoe Bend right next to it?
Anyway, we are in the process of planning events here.
David
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The 9 degree figure refers to how high the Sun will be in the sky at the end of annularity. Here are data for the Sun's height from your location: Start of partial eclipse 23.3° Start of annular eclipse 10.1° End of annular eclipse 9.3° Now let's just hope the weather cooperates. :) patrick On 21 Jul 2010, at 23:04, David Rankin wrote:
So, say the weather actually cooperates and this happens. I can see we are in the last 10 minute interval before sunset and they are showing the eclipse ending in Texas. We will only have 9 degrees to work with?
Thanks
David
I don't have the bone in my head that demands a perfectly concentric condition for an annular eclipse. I'll stick to the centerline for a total eclipse, but for an annular, not being exactly on centerline doesn't detract from either the visual, or photographic spectacle. In fact, as an artist (yes I was a real, bona-fide artist in a former life), I would avoid a perfectly concentric condition if imaging. My 2 cents. On 7/21/10, Patrick Wiggins <paw@wirelessbeehive.com> wrote:
The 9 degree figure refers to how high the Sun will be in the sky at the end of annularity.
Here are data for the Sun's height from your location:
Start of partial eclipse 23.3° Start of annular eclipse 10.1° End of annular eclipse 9.3°
Now let's just hope the weather cooperates. :)
patrick
On 21 Jul 2010, at 23:04, David Rankin wrote:
So, say the weather actually cooperates and this happens. I can see we are in the last 10 minute interval before sunset and they are showing the eclipse ending in Texas. We will only have 9 degrees to work with?
Thanks
David
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Either that or stay home and kiss your sister. Annular eclipses are fun but nothing like a total.
I don't have the bone in my head that demands a perfectly concentric
condition for an annular eclipse. I'll stick to the centerline for a total eclipse, but for an annular, not being exactly on centerline doesn't detract from either the visual, or photographic spectacle.
In fact, as an artist (yes I was a real, bona-fide artist in a former life), I would avoid a perfectly concentric condition if imaging.
My 2 cents.
On 7/21/10, Patrick Wiggins <paw@wirelessbeehive.com> wrote:
The 9 degree figure refers to how high the Sun will be in the sky at the end of annularity.
Here are data for the Sun's height from your location:
Start of partial eclipse 23.3° Start of annular eclipse 10.1° End of annular eclipse 9.3°
Now let's just hope the weather cooperates. :)
patrick
On 21 Jul 2010, at 23:04, David Rankin wrote:
So, say the weather actually cooperates and this happens. I can see we are in the last 10 minute interval before sunset and they are showing the eclipse ending in Texas. We will only have 9 degrees to work with?
Thanks
David
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Hey, we look at the sun, we look at the moon. Why not look at both at the same time? This "kissing a close relative" analogy doesn't hold water in certain southern Utah communities... ;o) On 7/24/10, erikhansen@thebluezone.net <erikhansen@thebluezone.net> wrote:
Either that or stay home and kiss your sister. Annular eclipses are fun but nothing like a total.
I don't have the bone in my head that demands a perfectly concentric
condition for an annular eclipse. I'll stick to the centerline for a total eclipse, but for an annular, not being exactly on centerline doesn't detract from either the visual, or photographic spectacle.
In fact, as an artist (yes I was a real, bona-fide artist in a former life), I would avoid a perfectly concentric condition if imaging.
My 2 cents.
On 7/21/10, Patrick Wiggins <paw@wirelessbeehive.com> wrote:
The 9 degree figure refers to how high the Sun will be in the sky at the end of annularity.
Here are data for the Sun's height from your location:
Start of partial eclipse 23.3° Start of annular eclipse 10.1° End of annular eclipse 9.3°
Now let's just hope the weather cooperates. :)
patrick
On 21 Jul 2010, at 23:04, David Rankin wrote:
So, say the weather actually cooperates and this happens. I can see we are in the last 10 minute interval before sunset and they are showing the eclipse ending in Texas. We will only have 9 degrees to work with?
Thanks
David
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I always aim to please. I almost hope that the neighbors were watching, this time. Small towns can get so dull. Kim -----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Chuck Hards Sent: Wednesday, July 21, 2010 9:09 AM To: Utah Astronomy Subject: Re: [Utah-astronomy] Measuring pupil size That's the funniest thing I've read all-day, thanks Kim! LOL! On 7/21/10, Kim <kimharch@cut.net> wrote:
BTW, I freaked out my wife when I set up the camera on a tripod in the bathroom in the middle of the night. I think she is still skeptical about what I was doing...
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Well, I have the fore mentioned exit pupil gauge, I passed it around during an event at the sun tunnels. The best that was measured was 8 mm as I recall. I am not sure where the idea came from that you need to use it with the lights on, it works very well at night. I can bring it to a SPOC Star party, I think I am scheduled to operate the Grim on July 31.
Erik BTW, I freaked out my wife when I set up the camera on a tripod in the
bathroom in the middle of the night. I think she is still skeptical about what I was doing...
Kim
-----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Kim Sent: Wednesday, July 21, 2010 8:01 AM To: 'Utah Astronomy' Subject: Re: [Utah-astronomy] Measuring pupil size
Patrick, Since you threw down the gauntlet (whether intentionally or not), I've spent the last couple of hours determining my pupil size. Didn't think I could sleep anyway.
I recall that the last time I tried this test years ago I used a mirror because I was using a film camera and didn't have a cable release that was long enough to simply direct the camera at my face for a self portrait. Tonight (this morning) I used my Nikon D70 digital camera, and of course it was much easier. I set up the camera to take a direct image of my face while holding a scale by my eye. I waited ten minutes after turning out the lights then shot the picture. I measured a pupil diameter of just under7mm.
From the age of about 12 I've tried to wear sunglasses whenever I am outdoors and this protection seems to have helped give me fairly good night vision. I double-checked my notes and the first time I did this pupil diameter test I actually had an 8mm pupil diameter. Wikipedia gives a range of between 5mm and 9mm for pupil size in young adults (http://en.wikipedia.org/wiki/Exit_pupil) so I don't think that 7.2mm or even 8mm is necessarily on the high side for my age at the time. You can see, however, that my age appears to be catching up with me.
Kim
-----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Patrick Wiggins Sent: Wednesday, July 21, 2010 1:49 AM To: Utah Astronomy Subject: Re: [Utah-astronomy] Measuring pupil size
Ah, good idea. Maybe we could have a "pupil measuring session" during a star party at SPOC where instead of using a mirror we could go in the SPOC garage and have someone take pictures of those wishing to be measured.
BTW, isn't 7.2mm a tad on the large size?
patrick
On 21 Jul 2010, at 01:37, Kim wrote:
I have used the following method to measure my pupil size: Set up a camera with a remote or cable release on a tripod in front of a mirror in a room that can be made completely dark. Focus the camera on your reflected image and prepare it to take a picture in the dark with the flash. (Beware not to use any redeye reduction pre-flash setting.) Turn out the lights and wait for your eyes to become completely dark adapted. Stand adjacent to the camera holding a subdivided millimeter scale next to your eye and take your picture. From the resulting image you can use the scale that you held by your eye to measure your fully dilated pupil size.
Last time I did this I measured my pupil to be about 7.2 mm in diameter.
Kim
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Patrick et all, Here is from Sky&Telescope last page of the article in the link: http://www.skyandtelescope.com/howto/basics/3304201.html It's easy to find your pupil diameter and observe how it changes in varying light. For a quick test, hold a pencil vertically just in front of your eye, resting it against your cheek and eyebrow. Close the other eye. A standard pencil is about 7 mm in diameter. Against bright light you'll see a fuzzy fringe surrounding an opaque core. Block most of the light from view by cupping your hands, and watch the core narrow. If the core thins away completely in dim light, so that you can see a little light right through its center, your pupil has enlarged beyond 7 mm. A better method is to use a pair of small slits in an opaque sheet with their inner edges separated by a measured distance. Look through the pair of slits while holding the paper against your eyebrow and cheek. (The holes should be about 14 mm in front of your eye, but this is not critical unless you are strongly nearsighted or farsighted and aren't wearing contact lenses.) You'll see two dim disks of light. If their edges barely touch, your pupil diameter equals the separation of the holes. The pupil does most of its dilating in the first second or two after you enter the dark, but it takes a few minutes to reach its absolute maximum size. Pupil dilation should not be confused with true dark adaptation, a chemical process that happens more slowly in the retina. Of course if you get an eye exam, just ask the doctor or assistant to measure them . . . I did last spring so I got the info. On Wed, Jul 21, 2010 at 1:37 AM, Kim <kimharch@cut.net> wrote:
I have used the following method to measure my pupil size: Set up a camera with a remote or cable release on a tripod in front of a mirror in a room that can be made completely dark. Focus the camera on your reflected image and prepare it to take a picture in the dark with the flash. (Beware not to use any redeye reduction pre-flash setting.) Turn out the lights and wait for your eyes to become completely dark adapted. Stand adjacent to the camera holding a subdivided millimeter scale next to your eye and take your picture. From the resulting image you can use the scale that you held by your eye to measure your fully dilated pupil size.
Last time I did this I measured my pupil to be about 7.2 mm in diameter.
Kim
-----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Patrick Wiggins Sent: Wednesday, July 21, 2010 12:26 AM To: utah astronomy utah astronomy listserve Subject: [Utah-astronomy] Measuring pupil size
During last evening's SLAS meeting Prez. Dave covered basic telescope math including several mentions of various optical systems' exit pupils (basically diameter/power).
During Advanced Training that followed I asked around about how to go about measuring the size of the eye's pupil.
Dave and I both remembered the pupil measurement device Edmund used to sell but Dave noted it didn't do much good since it had to be used with the lights on.
Anyone here have any ideas on how to measure pupil diameter under low-light conditions?
Thanks,
patrick
p.s. As was noted in the meeting, Dave's talk was a historic first in that it was the first time he had ever given a presentation with a computer and *NO* slide projector. Could this possibly mean SLAS's aged and long suffering slide projector is now going to join the Mickey Mouse telescope in well deserved retirement?!? _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php Visit the Wiki: http://www.utahastronomy.com
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-- Jay Eads
I am not sure the diameter of your pupils after getting a dilator from the optomelogist relates to what it does naturally. My memory of my eye exam is that it was painful to be in bright light for several hours.
Narcotics will also skew dilation, and of course low 02 will constrict. I remember F Desousa did not like observing at altitude because of this. Stephen O'mera also liked to wear 02 when observing at altitude.
From my last post, I am not sure why it hasn't appeared several hour after posting, the gauge I have is from sky&telescope. I is really much simpler than any method I have seen posted here.
Also, while I think it is a good idea to determine exit pupil of your eyepieces, I would not let it keep you from buying an eyepiece that yields a bigger field of view. For, instance I had and eyepiece that yielded a 10mm exit pupil, but it gave a 4 degree field of view. Views of the entire Veil Nebula and N. American are spectacular despite the exit pupil that is incompatible with the human eye. Erik Patrick et all,
Here is from Sky&Telescope last page of the article in the link:
http://www.skyandtelescope.com/howto/basics/3304201.html
It's easy to find your pupil diameter and observe how it changes in varying light. For a quick test, hold a pencil vertically just in front of your eye, resting it against your cheek and eyebrow. Close the other eye. A standard pencil is about 7 mm in diameter. Against bright light you'll see a fuzzy fringe surrounding an opaque core. Block most of the light from view by cupping your hands, and watch the core narrow. If the core thins away completely in dim light, so that you can see a little light right through its center, your pupil has enlarged beyond 7 mm.
A better method is to use a pair of small slits in an opaque sheet with their inner edges separated by a measured distance. Look through the pair of slits while holding the paper against your eyebrow and cheek. (The holes should be about 14 mm in front of your eye, but this is not critical unless you are strongly nearsighted or farsighted and aren't wearing contact lenses.) You'll see two dim disks of light. If their edges barely touch, your pupil diameter equals the separation of the holes.
The pupil does most of its dilating in the first second or two after you enter the dark, but it takes a few minutes to reach its absolute maximum size. Pupil dilation should not be confused with true dark adaptation, a chemical process that happens more slowly in the retina.
Of course if you get an eye exam, just ask the doctor or assistant to measure them . . . I did last spring so I got the info.
On Wed, Jul 21, 2010 at 1:37 AM, Kim <kimharch@cut.net> wrote:
I have used the following method to measure my pupil size: Set up a camera with a remote or cable release on a tripod in front of a mirror in a room that can be made completely dark. Focus the camera on your reflected image and prepare it to take a picture in the dark with the flash. (Beware not to use any redeye reduction pre-flash setting.) Turn out the lights and wait for your eyes to become completely dark adapted. Stand adjacent to the camera holding a subdivided millimeter scale next to your eye and take your picture. From the resulting image you can use the scale that you held by your eye to measure your fully dilated pupil size.
Last time I did this I measured my pupil to be about 7.2 mm in diameter.
Kim
-----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Patrick Wiggins Sent: Wednesday, July 21, 2010 12:26 AM To: utah astronomy utah astronomy listserve Subject: [Utah-astronomy] Measuring pupil size
During last evening's SLAS meeting Prez. Dave covered basic telescope math including several mentions of various optical systems' exit pupils (basically diameter/power).
During Advanced Training that followed I asked around about how to go about measuring the size of the eye's pupil.
Dave and I both remembered the pupil measurement device Edmund used to sell but Dave noted it didn't do much good since it had to be used with the lights on.
Anyone here have any ideas on how to measure pupil diameter under low-light conditions?
Thanks,
patrick
p.s. As was noted in the meeting, Dave's talk was a historic first in that it was the first time he had ever given a presentation with a computer and *NO* slide projector. Could this possibly mean SLAS's aged and long suffering slide projector is now going to join the Mickey Mouse telescope in well deserved retirement?!? _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php Visit the Wiki: http://www.utahastronomy.com
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Exactly, Erik echos my feelings on the subject. So, if your pupil is too small to accomodate a particular eyepiece/objective combination, you waste a bit of aperture. If you are after a wider FOV, it's one of the tradoffs you make, no big deal. I'm not going to pack a special reduced-aperture telescope along just for very low power, nor am I going to not use a particular eyepiece on a larger scope because I won't be able to use the entire objective. It's only at the very low power end that this comes up, one end of the "bell curve" of the full range of employed magnification. A non-issue, mostly just one of those abstract bits of info that's fun or interesting to mull over. On 7/21/10, erikhansen@thebluezone.net <erikhansen@thebluezone.net> wrote:
Also, while I think it is a good idea to determine exit pupil of your eyepieces, I would not let it keep you from buying an eyepiece that yields a bigger field of view. For, instance I had and eyepiece that yielded a 10mm exit pupil, but it gave a 4 degree field of view. Views of the entire Veil Nebula and N. American are spectacular despite the exit pupil that is incompatible with the human eye.
Actually, after explaining why, my ophthalmologist measured my pupils before they had the drops put into them. They were measured in natural light and in darkness so the reading I received was an accurate reading of what my pupil diameter is for each eye, and one is slightly larger than the other. Your ophthalmologist should be able to do this if you ask them and it usually sparks a conversation about vision and viewing which is informational. On Wed, Jul 21, 2010 at 7:42 PM, Chuck Hards <chuck.hards@gmail.com> wrote:
Exactly, Erik echos my feelings on the subject. So, if your pupil is too small to accomodate a particular eyepiece/objective combination, you waste a bit of aperture. If you are after a wider FOV, it's one of the tradoffs you make, no big deal. I'm not going to pack a special reduced-aperture telescope along just for very low power, nor am I going to not use a particular eyepiece on a larger scope because I won't be able to use the entire objective.
It's only at the very low power end that this comes up, one end of the "bell curve" of the full range of employed magnification.
A non-issue, mostly just one of those abstract bits of info that's fun or interesting to mull over.
On 7/21/10, erikhansen@thebluezone.net <erikhansen@thebluezone.net> wrote:
Also, while I think it is a good idea to determine exit pupil of your eyepieces, I would not let it keep you from buying an eyepiece that yields a bigger field of view. For, instance I had and eyepiece that yielded a 10mm exit pupil, but it gave a 4 degree field of view. Views of the entire Veil Nebula and N. American are spectacular despite the exit pupil that is incompatible with the human eye.
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-- Jay Eads
participants (9)
-
Chuck Hards -
daniel turner -
David Rankin -
Dunn, David -
erikhansen＠thebluezone.net -
Jay Eads -
Joe Bauman -
Kim -
Patrick Wiggins