How to objectively compare scopes? (possible scope test upcoming)
- Thread starter JimT
- Start date
A great way to test resolution is to set up some printed mater at 200yards and try to read it like an eye chart To test brightness put a dark object in the brush at dusk and try the different scopes side by side at different power settings as it gets dark. I don't know of any reliable way to test the adjustments except to burn amunition on an ACCURATE gun. Let us know how it turns out. /ubbthreads/images/graemlins/confused1.gif
dan newberry
New member
You can test the adjustments with a scope collimator (like a boresighter). That'll give a pretty good idea of adjustment precision, or lack thereof.
Zero the rifle at 100 yards, and with a rubber mallet whack the scope rings, front and rear, a few times. Then take another shot and see if it has moved. (That's what Outdoor Life did recently. A Cabela's scope of all things won that test, beating Leupold, Nikon, and Bushnell!
Dan
Zero the rifle at 100 yards, and with a rubber mallet whack the scope rings, front and rear, a few times. Then take another shot and see if it has moved. (That's what Outdoor Life did recently. A Cabela's scope of all things won that test, beating Leupold, Nikon, and Bushnell!
Dan
Using the Air Force resolution targets to determine resolution is pretty objective, and also pretty much a standard method that many people and organizations have used for years, when comparing pure optical quality between instruments. Setting up a newspaper or the like is another way of doing the same thing, just not well standardized.
Other than that, testing mechanical precision by setting the scopes up in a fixture (much, much better than using a colliminator) and noting the types and severity of abberations present is about all there is to it.
- DAA
Other than that, testing mechanical precision by setting the scopes up in a fixture (much, much better than using a colliminator) and noting the types and severity of abberations present is about all there is to it.
- DAA
CatShooter
New member
It is not possible to test scopes without proper equipment - which include an optical bench, projection screens and collimated targets.
Resolution charts don't help because even most poor scopes will resolve better than most people can see - plus the problems like spherical abboration cannot be detected or evaluated with the human eye.
The Airforce resolution charts were designed to measure film resolution in aerial survelence cameras.
Do you know what your eye resolution is in arc seconds? Howe many arc seconds do you see? How many SHOULD you see?
Do you know what you need to see when looking through a 10x scope at a resolution chart?
When a scope is poor, all you can say about it by looking through it is that "I can't see as well with this one as I could with the other one"... that is about like the ol' American Bandstand rating system of "I give it an 85 cuz it has a good beat and I can understand the words"
In the end, all that is necessary is that you can see what YOU need to see.
CatShooter
Resolution charts don't help because even most poor scopes will resolve better than most people can see - plus the problems like spherical abboration cannot be detected or evaluated with the human eye.
The Airforce resolution charts were designed to measure film resolution in aerial survelence cameras.
Do you know what your eye resolution is in arc seconds? Howe many arc seconds do you see? How many SHOULD you see?
Do you know what you need to see when looking through a 10x scope at a resolution chart?
When a scope is poor, all you can say about it by looking through it is that "I can't see as well with this one as I could with the other one"... that is about like the ol' American Bandstand rating system of "I give it an 85 cuz it has a good beat and I can understand the words"
In the end, all that is necessary is that you can see what YOU need to see.
CatShooter
JimT
New member
I think you're kind of missing the point here.
If I can print off the resolution targets at a size that I can see at 100 yards, or even 50 yards, then I can compare resolutions. I don't need numbers, I just need to compare them to each other so I know which one I want to buy another of. At the same time, I want something objective so I know I'm not fooling myself and so I can come back here and report what I found.
Believe it or not, the Navy uses a "calibrated eyeball" to check resolution on FLIR systems. I work with people that do this.
If I can print off the resolution targets at a size that I can see at 100 yards, or even 50 yards, then I can compare resolutions. I don't need numbers, I just need to compare them to each other so I know which one I want to buy another of. At the same time, I want something objective so I know I'm not fooling myself and so I can come back here and report what I found.
Believe it or not, the Navy uses a "calibrated eyeball" to check resolution on FLIR systems. I work with people that do this.
What I use is a box built to hold 6 scopes at a time. Rounds are cut 1", 30mm, and 34mm. These rounds(or slots) are where the tubes rest holding the scopes about half way. Then another matching set of rounds/slots are cut in a board that fits over the top of the scope tubes which hold all of them in place as if in rings. They won't be as tight as with rings but allows you to work with each one. Rubber bands can be used to hold the top and bottom of this box together. This way you can look at the same target with all scopes side by side. Allows you to eliminate or put in order least best to best or vice-versa.
I use a set of printed lines that form squares. The purpose of this is to change distance until the lines turn to black squares. Resolution can be measured in distance here. Also have a printed chart that is similar to the one used to check your eyes. It is printed in different fonts from large to small. This is set up at 100 yds. and each scope is checked to see how small of print can be observer.
Click adjustments will not be an easy test for these scopes as I am sure they have friction adjusstment instead of clicks. Adjustments are checked by use of a square test. Take a 12" by 12" piece of paper and place the smallest dot you can see with all scopes in the middle. Then go to the bottom right corner of the target 2" up and 2" over placing a tiny dot. From this dot measure 10" to the left of right dot and put another dot. Measure 10" up from that dot and place another. Then measure 10" right and put another dot.
After you have a perfect square of dots, us a compass to make a 1" circle around the left, left top, and right top of dots on the target. You can also use a quarter if you can center the dot with it and draw the circle about the dot. The purpose of the 1" circle is margin of error. At the dot left in the right bottom corner, make this one large enough for you to see with all scopes for an aiming point like the center one you sight rifle/load for testing in.
After target is made, place at 100 yds for testing. You need your rifle on a solid rest for this that does not move. Aim at dot in the lower right corner of target. Move windage point of impact 10"'s to the left. Aim at dot in right bottom corner and fire one shot. Move elevation up 10"'s, aim at same dot right bottom corner and fire another shot. Then, move windage point of impact 10"'s to the right and fire a shot. Finally, move elevation point of impact down 10"'s and fire the last shot. Repeat this until you have shot a 5-shot group into each circle of the square.
This is to check tracking of scope adjustments. Ideal, you should have a 1" or better 5-shot group inside each 1" circle. If scope does not track properly around the square you will have no problem seeing it. This will be extremely hard to do with friction type scope adjustments.
Low light testing, I revert back to the line and eye chart. Start checking each scope by using charts and noting times checked. Repeat these check in whatever time frame you wish until dark. You should then have readings timed for each scope in chart form with data for each one. Another point here is too have a set of woods about 100 yds away. As darkness falls see how deep into the woods you can see with each scope as it gets darker.
These should give you some idea of how well each scope funtions.
I use a set of printed lines that form squares. The purpose of this is to change distance until the lines turn to black squares. Resolution can be measured in distance here. Also have a printed chart that is similar to the one used to check your eyes. It is printed in different fonts from large to small. This is set up at 100 yds. and each scope is checked to see how small of print can be observer.
Click adjustments will not be an easy test for these scopes as I am sure they have friction adjusstment instead of clicks. Adjustments are checked by use of a square test. Take a 12" by 12" piece of paper and place the smallest dot you can see with all scopes in the middle. Then go to the bottom right corner of the target 2" up and 2" over placing a tiny dot. From this dot measure 10" to the left of right dot and put another dot. Measure 10" up from that dot and place another. Then measure 10" right and put another dot.
After you have a perfect square of dots, us a compass to make a 1" circle around the left, left top, and right top of dots on the target. You can also use a quarter if you can center the dot with it and draw the circle about the dot. The purpose of the 1" circle is margin of error. At the dot left in the right bottom corner, make this one large enough for you to see with all scopes for an aiming point like the center one you sight rifle/load for testing in.
After target is made, place at 100 yds for testing. You need your rifle on a solid rest for this that does not move. Aim at dot in the lower right corner of target. Move windage point of impact 10"'s to the left. Aim at dot in right bottom corner and fire one shot. Move elevation up 10"'s, aim at same dot right bottom corner and fire another shot. Then, move windage point of impact 10"'s to the right and fire a shot. Finally, move elevation point of impact down 10"'s and fire the last shot. Repeat this until you have shot a 5-shot group into each circle of the square.
This is to check tracking of scope adjustments. Ideal, you should have a 1" or better 5-shot group inside each 1" circle. If scope does not track properly around the square you will have no problem seeing it. This will be extremely hard to do with friction type scope adjustments.
Low light testing, I revert back to the line and eye chart. Start checking each scope by using charts and noting times checked. Repeat these check in whatever time frame you wish until dark. You should then have readings timed for each scope in chart form with data for each one. Another point here is too have a set of woods about 100 yds away. As darkness falls see how deep into the woods you can see with each scope as it gets darker.
These should give you some idea of how well each scope funtions.
mikegranger
Well-known member
Very good Steve. Thanks for the example. /ubbthreads/images/graemlins/grinning-smiley-003.gif
Yup, that will give you a really good idea of how one scope compares to another (or others).
Another thing that I've seen done, but have not messed with myself, is using a set of Charlie Hood's scope checker rings. About the time I decided to order a set from him, he stopped regular production. That was a couple years ago. Not sure if he even makes them at all anymore. I've seen some stuff revealed by those rings that make you just shake your head (like brand new Leupold Comp. series BR scopes that don't hold zero from shot to shot!).
One thing I know most of you already know, that I'll mention just because it hasn't been brought up, is how much difference there often is between two supposedly identical scopes. Just because one particular specimen of "model A" checks out better than one particular specimen of "model B", doesn't mean all A's are going to be better than all B's. Especially not if they are fairly close. For whatever reason, I've ended up having more Leupold 4.5-14x40's than anything else. Lining up four or five of them together and running through the kind of checks Steve outlined, there is a surprising amount of difference between the individual specimens. And before I got rid of them both, I had two Weaver V16's that I bought at the same time, that were night and day different. One was "okay" at 16x, the other would get so dark and fuzzy at 16x it wasn't even usable.
- DAA
Another thing that I've seen done, but have not messed with myself, is using a set of Charlie Hood's scope checker rings. About the time I decided to order a set from him, he stopped regular production. That was a couple years ago. Not sure if he even makes them at all anymore. I've seen some stuff revealed by those rings that make you just shake your head (like brand new Leupold Comp. series BR scopes that don't hold zero from shot to shot!).
One thing I know most of you already know, that I'll mention just because it hasn't been brought up, is how much difference there often is between two supposedly identical scopes. Just because one particular specimen of "model A" checks out better than one particular specimen of "model B", doesn't mean all A's are going to be better than all B's. Especially not if they are fairly close. For whatever reason, I've ended up having more Leupold 4.5-14x40's than anything else. Lining up four or five of them together and running through the kind of checks Steve outlined, there is a surprising amount of difference between the individual specimens. And before I got rid of them both, I had two Weaver V16's that I bought at the same time, that were night and day different. One was "okay" at 16x, the other would get so dark and fuzzy at 16x it wasn't even usable.
- DAA
Would have to agree with DAA on optics not being the same kinda like loads in rifles. However, in working with hundreds of scopes over the years, Leupold top end optics have provided the most trouble free use in my book. Some of the Euro's are really good but they all have little quirks that make them useless to me. Funny click adjustment, not enough adjustments, etc.......... pain in the butt for long range shooting. For those that sight-in and never move them they would be great! Schmidt & Bender is just awesome in the glass department and the new socpes they are suppose to be coming out with this year are suppose to finally have 1/4 min clicks!