I use a 23mm lens in Knoblok frames to shoot smallbore prone.
However there seems to be varying views as to the focal point of the lens. At the moment mine is in focus just beyond the end of the rifle, which keeps the front sight sharp but the target is a grey blob. Your opinions would be appreciated.
Shooting glasses
Moderators: pilkguns, Marcus, m1963, David Levene, Spencer
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Martin H
Bob,
You must have a sharp foresight. That is where the big aiming errors come from. It is far more accurate to centre a blurry target inside a sharp foresight than it is to centre a sharp target inside a blurry foresight.
It does depend on your eyes as to what you can get away with. As you get older and more long sighted then the focus has to be "forced" back towards the front sight. However it is nice to see a reasonably nice black target but remember the foresight must be sharp.
If you have a friendly optometrist then try one step either way.
Martin
You must have a sharp foresight. That is where the big aiming errors come from. It is far more accurate to centre a blurry target inside a sharp foresight than it is to centre a sharp target inside a blurry foresight.
It does depend on your eyes as to what you can get away with. As you get older and more long sighted then the focus has to be "forced" back towards the front sight. However it is nice to see a reasonably nice black target but remember the foresight must be sharp.
If you have a friendly optometrist then try one step either way.
Martin
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Nicole Hamilton
- Posts: 477
- Joined: Sat Jan 14, 2006 1:17 pm
- Location: Redmond, Washington, USA
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I'm becoming suspicious that the standard advice that you should choose a prescription that gives best focus at the exact distance to the front sight may be a little simplistic for all of us older folks with diminished depth of field.
We all know it's not possible to get all three elements, both front and rear sight and the black, all in focus at the same time, so we all agree that the front sight has to be in best focus. And of course, I think we all agree that sight alignment (top edges of front and rear sight lined up with same space on either side of the front sight) is way more important than sight picture (getting the front sight perfectly aligned with the black.)
But I'm beginning to think these points are more relative, than absolute. On the one hand, if you could actually get all three elements in focus at one time, who wouldn't choose that? Similarly, if you could get the front sight in absolutely perfect focus, but only by getting the black so out of focus you couldn't even tell it was there, does anything think that would be a good idea? So it's not about choosing one thing to be in focus to the exclusion of anything else, it's about satisficing the need to get each element sufficiently in focus that you can get a repeatable result.
What got me to thinking about this was some personal and, admittedly, not very scientific observations switching between two different pairs of glasses. As I've gotten older, I've gotten more nearsighted, so I have an old pair that gives me noticably better focus on the front sights for all my guns but not as good at distance as my new ones. And of course, the farther the distance, the bigger the difference. What I've discovered is that for 10m air pistol, I definitely shoot better with the old glasses. In 50-foot standard pistol, it's a toss-up though I think I prefer my new prescription. In 25-yard free pistol, I do better with my new prescription; with the old prescription, I think the black is just too fuzzy.
As usual, YMMV and all that. And please don't misunderstand this to be even my own last word on the matter; I'm still experimenting. But I would appreciate hearing others' thoughts on the subject.
We all know it's not possible to get all three elements, both front and rear sight and the black, all in focus at the same time, so we all agree that the front sight has to be in best focus. And of course, I think we all agree that sight alignment (top edges of front and rear sight lined up with same space on either side of the front sight) is way more important than sight picture (getting the front sight perfectly aligned with the black.)
But I'm beginning to think these points are more relative, than absolute. On the one hand, if you could actually get all three elements in focus at one time, who wouldn't choose that? Similarly, if you could get the front sight in absolutely perfect focus, but only by getting the black so out of focus you couldn't even tell it was there, does anything think that would be a good idea? So it's not about choosing one thing to be in focus to the exclusion of anything else, it's about satisficing the need to get each element sufficiently in focus that you can get a repeatable result.
What got me to thinking about this was some personal and, admittedly, not very scientific observations switching between two different pairs of glasses. As I've gotten older, I've gotten more nearsighted, so I have an old pair that gives me noticably better focus on the front sights for all my guns but not as good at distance as my new ones. And of course, the farther the distance, the bigger the difference. What I've discovered is that for 10m air pistol, I definitely shoot better with the old glasses. In 50-foot standard pistol, it's a toss-up though I think I prefer my new prescription. In 25-yard free pistol, I do better with my new prescription; with the old prescription, I think the black is just too fuzzy.
As usual, YMMV and all that. And please don't misunderstand this to be even my own last word on the matter; I'm still experimenting. But I would appreciate hearing others' thoughts on the subject.
But you can get all three in focus - use an iris. But don't expect your scores to improve because they almost certainly won't. As you know there's a whole lot more to shooting than getting the sight picture right. That grey matter in between our ears really messes things up when it starts trying too hard.Nicole Hamilton wrote:But I'm beginning to think these points are more relative, than absolute. On the one hand, if you could actually get all three elements in focus at one time, who wouldn't choose that? Similarly, if you could get the front sight in absolutely perfect focus, but only by getting the black so out of focus you couldn't even tell it was there, does anything think that would be a good idea? So it's not about choosing one thing to be in focus to the exclusion of anything else, it's about satisficing the need to get each element sufficiently in focus that you can get a repeatable result.
As we get older I'm pretty sure our eye muscles just can't change focal length as quick. That's why we perceive a greater field of focus when we're younger. I'm believe that if you can maintain proper focus on the foresight the other elements will be sharp enough for maximum scores, all we then have to do is stop thinking and shaking the gun ;-)
Rob.
Does depth of field diminish with age? Thought it was more related to light level and f-stop.Nicole Hamilton wrote:...older folks with diminished depth of field...
Always accepted that 'younger' eyes do not have greater depth of field, only that they have greater ability to switch focal length.
If correct, this would mean that 'old' eyes and 'young' eyes would have the same bluriness of rear sight and target when focussed on the front sight (???)
Perhaps one of the eye professionals can clear this up (no pun intended)
Regards,
Spencer
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wrc177
But, Rob, the problem with wonky eyesight is that ALL elements don't just fall into place if the front sight is sharp enough. That gray blob out there is a true blob - usually not round, and probably changing in shape from moment to moment. Given a choice, I would most certainly want both the front sight, and what I'm looking at to be clear.
In my case, I can see that my limiting factor is eyesight every time I put the scope on the smallbore rifle and shoot prone - even at 50 ft. My scores go up dramatically, and I'm sure that it is because I can see exactly. A good shooer who can see a nice sharp sight picture would not have such a dramatic difference between irons and scope scores.
YMMV. It's one thing to hold rather sort-of in the center (blob sighting), it's another to hold perfect 10x center.
In my case, I can see that my limiting factor is eyesight every time I put the scope on the smallbore rifle and shoot prone - even at 50 ft. My scores go up dramatically, and I'm sure that it is because I can see exactly. A good shooer who can see a nice sharp sight picture would not have such a dramatic difference between irons and scope scores.
YMMV. It's one thing to hold rather sort-of in the center (blob sighting), it's another to hold perfect 10x center.
USAS rifle rule 4.4 allows up to a 1.5x optic adjustment in either the front or rear sight 9or on the glasses) for senior shooters (age 45+), but perhaps we need to begin asking that a 1.5x scope be allowed. We wouldn't qualify for finals or records, but I can't help believe it would keep more folks active.
I too shoot much better with a scope at 50 feet than with apertures at 10M due to vision problems (floaters), and am about to stop all ISSF shooting becasue of that.
I too shoot much better with a scope at 50 feet than with apertures at 10M due to vision problems (floaters), and am about to stop all ISSF shooting becasue of that.
But you are simply never gonna get that no matter what age you are. The human eye cannot hold focus at say 1m and 50m at the same time it's just not possible. Now your wobbly sight image sounds like an astigmatism - but I'm no expert. The only thing you can do to increase the depth of field is to reduce the aperture (hence an iris). I fail to see how a magnifying lens will make any difference to focal length problems. I really don't have any answers but as we all get older we have to adjust and change and if that means shooting with a scope then so be it. There are plenty of events where they are allowed, although for obvious reasons many where they aren't.wrc177 wrote:But, Rob, the problem with wonky eyesight is that ALL elements don't just fall into place if the front sight is sharp enough. That gray blob out there is a true blob - usually not round, and probably changing in shape from moment to moment. Given a choice, I would most certainly want both the front sight, and what I'm looking at to be clear.
Rob.
Shooting glasses
To me the age problem is paramount. I gave up shooting 25 years ago and three years back I decided to take up the sport. I am now 64 years old and I found I had to get some shooting glasses.
I find that I have a very short time to get the correct sight picture compared to years back. It seems that it only takes a few seconds to get false sighting and if I fire on that picture I will get an eight. If I really go for it and shoot the first good sight I see it invariably is a ten or central.
Thanks for all the replys to my original query.
I find that I have a very short time to get the correct sight picture compared to years back. It seems that it only takes a few seconds to get false sighting and if I fire on that picture I will get an eight. If I really go for it and shoot the first good sight I see it invariably is a ten or central.
Thanks for all the replys to my original query.
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Martin H
[quote]And of course, the farther the distance, the bigger the difference.
Nicole,
I agree, the further the distance, the more I seem to need a better focus on the target. At 10m AR I can get away with no lense, at 25yd SB I need -0.25 correction and 50m I seem to need -.50 correction.
At the age of 42 I am just starting have the occasional problem with keeping the front sight in focus. Sometimes it is difficult, esp in the mornings when my eyes are fresh and rested. Then I have used a lens one step weaker. Of course, after working all day with a PC I find I need that stronger lens and the front sight stays sharp.
All very frustrating until I realised what was happening.
Cheers
Martin
Nicole,
I agree, the further the distance, the more I seem to need a better focus on the target. At 10m AR I can get away with no lense, at 25yd SB I need -0.25 correction and 50m I seem to need -.50 correction.
At the age of 42 I am just starting have the occasional problem with keeping the front sight in focus. Sometimes it is difficult, esp in the mornings when my eyes are fresh and rested. Then I have used a lens one step weaker. Of course, after working all day with a PC I find I need that stronger lens and the front sight stays sharp.
All very frustrating until I realised what was happening.
Cheers
Martin
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Martin H