TargetTalk

Nicole Hamilton wrote:My suspicion, and I think this article supports it, is that our effective depth of field, i.e., our overall ability to process an image containing both in-focus and out-of-focus elements probably diminishes with age. I don't think the whole story is just about optics. I think it's more complex.

I'm sure you're right that it is more complex than just optics. It is also fair to say that different peoples eyes and other body systems change in a different way with age. I certainly notice my eyes take longer to focus than they used to and I'm only a young 40 ;-)

Rob.

RobStubbs wrote:I'm only a young 40 ;-)

You're right. 40 is young. I'm 55. Just wait.

Heck I'm only 51 and I an thinking of inventing the first trifocals.
I have trouble seeing which way the air pistol pellets are facing and I wear bifocals!!
Do you think there would be a market for such an animal?
When I am wearing my shooting glasses I don't have the benefit of the close up lens and so count pellets by feel and try to do the same when putting them in my air pistol. Sometimes they go in backwards - interestingly it doesn't make a noticeable difference to the end result for the shot.

ColinC wrote:Heck I'm only 51 and I an thinking of inventing the first trifocals.
I have trouble seeing which way the air pistol pellets are facing and I wear bifocals!!
Do you think there would be a market for such an animal?
When I am wearing my shooting glasses I don't have the benefit of the close up lens and so count pellets by feel and try to do the same when putting them in my air pistol. Sometimes they go in backwards - interestingly it doesn't make a noticeable difference to the end result for the shot.

I don't quite follow that. Shooting glasses make you near sighted so as to focus on the foresight. That should therefore make it much easier for you to see the pellets not more difficult.

Rob.

RobStubbs wrote:I don't quite follow that. Shooting glasses make you near sighted so as to focus on the foresight. That should therefore make it much easier for you to see the pellets not more difficult.

Not when you're used to wearing bi-focals or vari-focals Rob. You've still got that little pleasure to come.

re Rob's - I don't quite follow that. Shooting glasses make you near sighted so as to focus on the foresight. That should therefore make it much easier for you to see the pellets not more difficult.

I'm with Colin (gasp!), in the shooting position the sights are about 1 m away, when loading about 200-300 mm - with older eyes that is qiute a difference!

On the tri-focals: my optometrist uses spectacles with left eye long distance / right eye for short distances. It works for her: I am tempted...

Spencer

Spencer wrote: I'm with Colin (gasp!), in the shooting position the sights are about 1 m away, when loading about 200-300 mm - with older eyes that is qiute a difference!

Gee - I hope my eyes never get that bad ;)

On the tri-focals: my optometrist uses spectacles with left eye long distance / right eye for short distances. It works for her: I am tempted...

Spencer

You could always change your glasses to load - or have a flip up 'loading' lens - like those clip on flip up sunglasses <rules permitting of course>.

Rob.

Spencer wrote:re Rob's - I don't quite follow that. Shooting glasses make you near sighted so as to focus on the foresight. That should therefore make it much easier for you to see the pellets not more difficult.

The problem is Spencer that with vari-focals you have 2 different prescriptions, one to let you see things far away and one to let you see things close to you. The shooting prescription is associated with the former, so you can then loose the ability to see things close to you (closer than the sights.

This is all obviously dependant on the relative prescription strengths.

Spencer wrote: On the tri-focals: my optometrist uses spectacles with left eye long distance / right eye for short distances. It works for her: I am tempted...

Back when I was shooting IPSC and IDPA, I faced a similar problem - glasses that would allow me move around and identify targets to shoot at; and glasses that would allow me to focus on the front sight when shooting. I opted for glasses with the left lens for distance, the right lens for the sight, and 'reading lenses' at the bottom for scoring targets. Worked quite well at the time. Decot makes specialty lenses that do similar things, e.g. a vari-focus lens with a large 'bifocal' area at the top that allows you to focus on the front sight by lowering your head slightly.

Fred Mannis wrote:
Back when I was shooting IPSC and IDPA, I faced a similar problem - glasses that would allow me move around and identify targets to shoot at; and glasses that would allow me to focus on the front sight when shooting. I opted for glasses with the left lens for distance, the right lens for the sight, and 'reading lenses' at the bottom for scoring targets. Worked quite well at the time. Decot makes specialty lenses that do similar things, e.g. a vari-focus lens with a large 'bifocal' area at the top that allows you to focus on the front sight by lowering your head slightly.

Fred,
how long did it take to adjust to the one short/ one long lens (and back again)?

Spencer

Spencer wrote: Fred,
how long did it take to adjust to the one short/ one long lens (and back again)?

I turned it over to my subconscious :-).

Seriously, I never thought about it. Looking downrange I could clearly see the targets, brought the gun up, directed my attention to the in focus front sight, fired, looked over the top of the pistol and could clearly see targets again. Of course, what you lose in this is depth perception, so I had to exercise care if the course of fire required movement, but I never tripped or fell, even when (as in IDPA) having to fire while moving.

Hope you can get it to work for you.

Fred

Thanks, Nicole for your summary of the ageing eye. A dispassionate scientific approach was overdue IMHO.

One of the most dramatic effects on the eye of age is the decrease in dynamic range the fovea can cope with. The worst effect is the loss of the eye's ability to CHANGE focus (not depth of focus). The use of an iris allows one to play with brightness and depth of focus. It might work or it might disappoint: it's not really possible to predict for an individual.

If anyone with a moderate or severe refractive error wants to amuse themselves with pinhole optics, make a large sewing-needle hole through opaque paper, hold it as close as possible to your eye, and be amazed how in-focus the world is AT ALL DISTANCES, without your expensive spectacles. Bad luck if you are severely astigmatic! The standard explanation of this is because only the light rays which are very close to the optical axis are allowed through, and over this area, the curvature af a lens isn't much different from flat. This is why large-aperture photographic lenses are so expensive - small-aperture lenses don't have to be anything like as optically good.

If you use a blinder, make sure your blinded eye receives enough light to keep your pupils as small as possible. However, too much light will confuse the brain and reduce the perceived contrast of the image seen by the unblinded eye.

Smoking is extremely bad for the health of the retina.

Old eyeball wrote:One of the most dramatic effects on the eye of age is the decrease in dynamic range the fovea can cope with. The worst effect is the loss of the eye's ability to CHANGE focus (not depth of focus).

That's my experience, though I didn't understand why it happens. I find it takes me a measurable amount of time (~ 1-2 sec) to focus on the front sight. I now tend to keep my eyes closed until the gun is above the target and I can see the front sight clearly against the light background.

The lengthening time it takes you to change from distant to near focus, and vice versa, is because the flexibility of the lens in your eye decreases with age. Eventually, you will have virtually no accommodation ability and need three pairs of spectacles! My accommodation is getting close to zero in my mid-50s! Bugger!

Welcome to the incipient geriatric population!

Just remembered - there's another effect which may be important.

When you make an effort to accommodate (focus on a nearer object), the pupil constricts. This therefore increases depth of field. If you arrange your eyeglass prescription so that it takes a bit of effort to bring your focus close enough, you will ensure that the accommodation effort drives the pupil to constrict. It may therefore be a mistake to chose correction so that the foresight is in focus when your eye thinks it is focussing at infinity (ie relaxed, not accommodating). Also, I find that the effort of keepin the foresight in focus really hooks my attention onto the foresight (I was going to say focusses my attention, but it's getting confusing enough without bad puns). The disadvantage is possible fatigue.

When you get old, you just can't win!

Old eyeball wrote:When you make an effort to accommodate (focus on a nearer object), the pupil constricts. This therefore increases depth of field. If you arrange your eyeglass prescription so that it takes a bit of effort to bring your focus close enough, you will ensure that the accommodation effort drives the pupil to constrict. It may therefore be a mistake to chose correction so that the foresight is in focus when your eye thinks it is focussing at infinity (ie relaxed, not accommodating). Also, I find that the effort of keepin the foresight in focus really hooks my attention onto the foresight (I was going to say focusses my attention, but it's getting confusing enough without bad puns). The disadvantage is possible fatigue.

When you get old, you just can't win!

I would imagine the constriction of the eyeball is minimal and not enough to significantly alter the depth of focus. The downside in eye fatigue would in my opinion far outweigh any possible benefit. Old eyes suffer worse so I would suggest anything you can do to reduce eyestrain / fatigue would be of use.

Rob.

Actually, the pupillary constriction accompanying accommodation can be dramatic. In an experimental situation, not really applicable to shooting because of the fatigue you correctly note, one can achieve an astonishing depth of focus, when trying to focus on a near object. I can still do this at age 53. However, that's experiment, not real world shooting.

What I want to emphasize is, whether it's your pupil, or an orthoptic, you can control the desired depth of focus. Whether it helps your performance is, of course, up to you.

This really is the solution to most shooting problems. The targrt doesen't move. the gun moves ,and the allignment of the sights moves. The target only catches the bullet so we can score the target. The target should be percieved as a grey, fuzzy ball out at a distance Shoot tens Bill Horton

This really is the solution to most shooting problems. The targrt doesen't move. the gun moves ,and the allignment of the sights moves. The target only catches the bullet so we can score the target. The target should be percieved as a grey, fuzzy ball out at a distance Shoot tens Bill Horton

This is a very interesting discussion. I think for most people getting a dedicated pair of shooting glasses with the right prescription and using an aperture to maximize the apparent sharpness of the sights will go a long way towards improving sight picture.

In my case, I use +0.75 diopter over my distance prescription and have been doing ok. I've also given up on my contact lenses, they get blurry when I blink (makes for a lot of fun during rapid fire!).

I can sympathize with the air pistol shooters however. Since I'm near sighted, I can look under my glasses to load pellets, but with my contacts I can't tell if the pellets are backwards or forwards. The nice thing about a pair of fancy shooting glasses is that you can hang a lens holder on the non-shooting eye displaced from the occluder with a close up lens to see the pellets.

They should just let shooters over the age of 50 use .22 caliber pellets....

Steve.