Atomic Chicken
Registered with the D.O.E.
Greetings!
Today, I began a project that will eventually result in a new binocular oriented website I am getting ready to create. My main goal with this project is to do completely objective scientific comparisons of various binocular models, presenting information to help potential buyers select binoculars based on what is most important to them. Of course, the view and how the buyer feels about the view is really the ultimate determining factor, but in some cases binoculars are so close that it helps to compare specifications and objective scientific measurements the binocular companies seem hesitant to publish.
The first aspect of this project is to define a standardized measurement system for resolution measurements, and to do a sample run using several models of binoculars I own. I will be doing MUCH more of this type of measurement in the future, both at optics shops and with my own optics as my binocular collection grows. I think I have arrived at a method that should eliminate almost all extraneous factors, and provide solid and reliable data.
In order to present meaningful, scientifically derived, and (most importantly) OBJECTIVE information, I have approached the resolution testing using the following method:
#1 - All binoculars are mounted to a tripod mounted universal binocular clamp, devised and machined by me in order to secure the binoculars under test securely and eliminate all vibration and shaking. This also assures that the binocular can be correctly pointed, with the test chart properly centered in the view.
#2 - The test chart used, also devised by myself, contains a series of 54 zones, each approx. 1" square. Each zone contains either horizontal or vertical parallel lines that are of a fixed width and a fixed spacing, both the same dimension within that zone. The chart contains zones for 0.005"-0.020" in 0.001" increments, 0.022"-0.030" in 0.002" increments, 0.035"-0.050" in 0.005" increments, and finally a 0.060" and 0.070" zone. The chart is divided into two halves, with the upper half consisting of vertical parallel line zones for determining the binoculars horizontal discrimination, and the lower half of the chart is composed of the same measurement zones repeated with horizontal parallel line zones for determining the binoculars vertical resolution discrimination. The chart is printed on a 1200DPI laser printer on 98 brightness 24lb thick paper, and checked carefully for printing defects before use. This test chart was devised because it will give solid information on the actual resolution capabilities of the binocular in both axis, and the resulting measurements can easily be converted mathematically into an arc measurement if needed (example: 6 arc seconds or 5.4 arc seconds).
Edit: I've posted the chart as a .pdf file in the following thread message for download.
#3 - The test chart is hung on a wall at the end of a hallway, and the binocular objective lens is set to the exact same height as the center of the test chart. The binocular objective lens is set exactly 30 feet from the target, measured to +/- 0.5" tolerance.
#4 - All lighting in the area is extinguished. The test chart is illuminated by a single 75 watt bare light bulb which is located exactly 6 feet from the chart, and 2 feet to one side. The bulb is shielded completely in the direction of the binoculars by a large book, which has a matte black cover. This keeps light from reaching the binoculars from the bulb directly, which could cause internal reflections or other visual artifacts. The matte black book cover keeps the book blocking the light source from reflecting extra light back onto the test chart, avoiding extra light that might skew the results. The other end of the hall, where the binoculars are located, is kept completely dark during the testing. The testing is performed after midnight, to assure no sunlight enters the house.
#5 - After focusing, assuring that the diopter adjustment is properly set, and getting the clearest image of the test chart possible, the chart zones are examined one by one from left to right, and top to bottom, until a zone is reached where the "grayness" of the fused lines is replaced by actual visible lines. Even if the lines are fuzzy or hazy, the point is that the zone where the binocular begins to separate the lines into visible separate entities is the zone that determines the resolution discrimination for the test. The next zone to the left should remain as a uniform gray patch, with no visible line separation. The process is repeated for both vertical and horizontal resolution, and the results are logged.
#6 - Meaning of resulting measurements. Each binocular is given an h (horizontal resolution, from parallel vertical lines) rating, and a v (vertical resolution, from parallel horizontal lines) rating. The smaller the number, the better. An example would be:
Brand X 8x42
0.013h 0.014v
This would mean that the binocular was able to resolve vertical parallel lines that are 0.013" thick spaced 0.013" apart, meaning that the binocular is capable of horizontal discrimination of 0.013". It can also resolve parallel horizontal lines 0.014" thick spaced 0.014" apart, meaning that the binocular is capable of vertical resolution of 0.014". This result would mean that the binocular is capable of slightly better horizontal resolution than vertical. Since lenses are circular, you would expect the two numbers to be identical - but I've actually been surprised so far at how much difference between the two measurements some binoculars exhibit.
Resolution test results for my binoculars (Lower numbers are better):
===================================================
Rugged Exposure 10x25 Waterproof
0.020h 0.016v
Barska 16x32 Compact
0.013h 0.012v
Rugged Exposure 10x42 Waterproof Roof Prism
0.012h 0.012v
Bausch&Lomb 7x42 Discoverer
0.013h 0.013v
Zeiss Victory 8x20 Compact
0.012h 0.012v
Nikon HG 8x32
0.012h 0.011v
Pentax SP 10x50
0.010h 0.010v
Note that the cheapest binocular (the Rugged Exposure 10x25 Waterproof at $20.00) had the worst deviation between horizontal and vertical resolution results. Also, interestingly enough, the Nikon HG 8x32 seems slightly better at resolving vertical detail than horizontal (or worse at resolving horizontal detail than vertical, depending on how you look at it! )- a trait not shared by any other high end binocular I tested.
Keep in mind that resolution says NOTHING about the overall image quality of the binocular, only it's ability to resolve detail. For example, the Barska 16x32 is my dimmest pair of binoculars, these are like looking down dark tunnels at a flashlight at the other end. After testing those binoculars, the next pair seemed like someone had suddenly turned on the lights! Also, the other cheap pair, the Rugged Exposure 10x25 had such incredibly poor optical quality they were like looking down two tubes of fog, oil, and dimness all mixed together. These are EXTREMELY unpleasant to use, they are definite headache specials. I purchased them recently to disassemble for a tutorial I will be placing on my website, so this is probably the last time I will be looking through them - thank god! The Rugged Exposure 10x42, on the otherhand, is a sheer joy to look through and continue to completely blow me away with their magnificent view. How someone can make a pair of binoculars like that and only charge $60 for them completely mystifies me. The Nikon HG 8x32 easily had the best view of all binoculars tested, with the Bausch&Lomb 7x42 Discoverer coming in VERY close 2nd. Neither of these binoculars had the best resolution, however, which was achieved by the Pentax SP 10x50. Once again, resolution and overall image quality are not necessarily related.
In any case, I hope you have all enjoyed reading this extra-long post, I will keep the results coming as I test more binoculars in the future. I am hoping to have my website up in 2 or 3 weeks, there is a lot of work to do before I will be ready for the test run.
Edit: One more thing to note is that magnification has no relationship to resolution. Bigger is not always better... sometimes a good 7x or 8x will resolve more detail than a mediocre 10x. The Barska 16x32 and Rugged Exposure 10x25 results above, when compared to the other binoculars, clearly demonstrate this interesting effect.
Best wishes,
Bawko
Today, I began a project that will eventually result in a new binocular oriented website I am getting ready to create. My main goal with this project is to do completely objective scientific comparisons of various binocular models, presenting information to help potential buyers select binoculars based on what is most important to them. Of course, the view and how the buyer feels about the view is really the ultimate determining factor, but in some cases binoculars are so close that it helps to compare specifications and objective scientific measurements the binocular companies seem hesitant to publish.
The first aspect of this project is to define a standardized measurement system for resolution measurements, and to do a sample run using several models of binoculars I own. I will be doing MUCH more of this type of measurement in the future, both at optics shops and with my own optics as my binocular collection grows. I think I have arrived at a method that should eliminate almost all extraneous factors, and provide solid and reliable data.
In order to present meaningful, scientifically derived, and (most importantly) OBJECTIVE information, I have approached the resolution testing using the following method:
#1 - All binoculars are mounted to a tripod mounted universal binocular clamp, devised and machined by me in order to secure the binoculars under test securely and eliminate all vibration and shaking. This also assures that the binocular can be correctly pointed, with the test chart properly centered in the view.
#2 - The test chart used, also devised by myself, contains a series of 54 zones, each approx. 1" square. Each zone contains either horizontal or vertical parallel lines that are of a fixed width and a fixed spacing, both the same dimension within that zone. The chart contains zones for 0.005"-0.020" in 0.001" increments, 0.022"-0.030" in 0.002" increments, 0.035"-0.050" in 0.005" increments, and finally a 0.060" and 0.070" zone. The chart is divided into two halves, with the upper half consisting of vertical parallel line zones for determining the binoculars horizontal discrimination, and the lower half of the chart is composed of the same measurement zones repeated with horizontal parallel line zones for determining the binoculars vertical resolution discrimination. The chart is printed on a 1200DPI laser printer on 98 brightness 24lb thick paper, and checked carefully for printing defects before use. This test chart was devised because it will give solid information on the actual resolution capabilities of the binocular in both axis, and the resulting measurements can easily be converted mathematically into an arc measurement if needed (example: 6 arc seconds or 5.4 arc seconds).
Edit: I've posted the chart as a .pdf file in the following thread message for download.
#3 - The test chart is hung on a wall at the end of a hallway, and the binocular objective lens is set to the exact same height as the center of the test chart. The binocular objective lens is set exactly 30 feet from the target, measured to +/- 0.5" tolerance.
#4 - All lighting in the area is extinguished. The test chart is illuminated by a single 75 watt bare light bulb which is located exactly 6 feet from the chart, and 2 feet to one side. The bulb is shielded completely in the direction of the binoculars by a large book, which has a matte black cover. This keeps light from reaching the binoculars from the bulb directly, which could cause internal reflections or other visual artifacts. The matte black book cover keeps the book blocking the light source from reflecting extra light back onto the test chart, avoiding extra light that might skew the results. The other end of the hall, where the binoculars are located, is kept completely dark during the testing. The testing is performed after midnight, to assure no sunlight enters the house.
#5 - After focusing, assuring that the diopter adjustment is properly set, and getting the clearest image of the test chart possible, the chart zones are examined one by one from left to right, and top to bottom, until a zone is reached where the "grayness" of the fused lines is replaced by actual visible lines. Even if the lines are fuzzy or hazy, the point is that the zone where the binocular begins to separate the lines into visible separate entities is the zone that determines the resolution discrimination for the test. The next zone to the left should remain as a uniform gray patch, with no visible line separation. The process is repeated for both vertical and horizontal resolution, and the results are logged.
#6 - Meaning of resulting measurements. Each binocular is given an h (horizontal resolution, from parallel vertical lines) rating, and a v (vertical resolution, from parallel horizontal lines) rating. The smaller the number, the better. An example would be:
Brand X 8x42
0.013h 0.014v
This would mean that the binocular was able to resolve vertical parallel lines that are 0.013" thick spaced 0.013" apart, meaning that the binocular is capable of horizontal discrimination of 0.013". It can also resolve parallel horizontal lines 0.014" thick spaced 0.014" apart, meaning that the binocular is capable of vertical resolution of 0.014". This result would mean that the binocular is capable of slightly better horizontal resolution than vertical. Since lenses are circular, you would expect the two numbers to be identical - but I've actually been surprised so far at how much difference between the two measurements some binoculars exhibit.
Resolution test results for my binoculars (Lower numbers are better):
===================================================
Rugged Exposure 10x25 Waterproof
0.020h 0.016v
Barska 16x32 Compact
0.013h 0.012v
Rugged Exposure 10x42 Waterproof Roof Prism
0.012h 0.012v
Bausch&Lomb 7x42 Discoverer
0.013h 0.013v
Zeiss Victory 8x20 Compact
0.012h 0.012v
Nikon HG 8x32
0.012h 0.011v
Pentax SP 10x50
0.010h 0.010v
Note that the cheapest binocular (the Rugged Exposure 10x25 Waterproof at $20.00) had the worst deviation between horizontal and vertical resolution results. Also, interestingly enough, the Nikon HG 8x32 seems slightly better at resolving vertical detail than horizontal (or worse at resolving horizontal detail than vertical, depending on how you look at it! )- a trait not shared by any other high end binocular I tested.
Keep in mind that resolution says NOTHING about the overall image quality of the binocular, only it's ability to resolve detail. For example, the Barska 16x32 is my dimmest pair of binoculars, these are like looking down dark tunnels at a flashlight at the other end. After testing those binoculars, the next pair seemed like someone had suddenly turned on the lights! Also, the other cheap pair, the Rugged Exposure 10x25 had such incredibly poor optical quality they were like looking down two tubes of fog, oil, and dimness all mixed together. These are EXTREMELY unpleasant to use, they are definite headache specials. I purchased them recently to disassemble for a tutorial I will be placing on my website, so this is probably the last time I will be looking through them - thank god! The Rugged Exposure 10x42, on the otherhand, is a sheer joy to look through and continue to completely blow me away with their magnificent view. How someone can make a pair of binoculars like that and only charge $60 for them completely mystifies me. The Nikon HG 8x32 easily had the best view of all binoculars tested, with the Bausch&Lomb 7x42 Discoverer coming in VERY close 2nd. Neither of these binoculars had the best resolution, however, which was achieved by the Pentax SP 10x50. Once again, resolution and overall image quality are not necessarily related.
In any case, I hope you have all enjoyed reading this extra-long post, I will keep the results coming as I test more binoculars in the future. I am hoping to have my website up in 2 or 3 weeks, there is a lot of work to do before I will be ready for the test run.
Edit: One more thing to note is that magnification has no relationship to resolution. Bigger is not always better... sometimes a good 7x or 8x will resolve more detail than a mediocre 10x. The Barska 16x32 and Rugged Exposure 10x25 results above, when compared to the other binoculars, clearly demonstrate this interesting effect.
Best wishes,
Bawko
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