High Resolution Test Patterns for testing imaging systems The first two (ISO 12233 chart, wedges) can be evaluated by eye. The other patterns are mostly for computer measurement & analysis. The wedges, squares, zones and stars were generated by Imatest and that program can also analyze many of these charts. The “Dead Leaves” chart was the first to test a camera’s ability to reproduce texture; Imatest has improved upon this with our “Spilled Coins” chart, which is perfectly scale invariant, producing reliable and consistent test results. Dynamic Range Charts. Test a number of image quality factors at once.

I personally never had any auto-focusing problem with any lens or camera I ever owned. It seems that these days, members of every blog and forum sites are talking about checking and adjusting the auto-focus on their lenses or DSLR. I think there is a perception that many lenses or DSLR cameras are having front or rear focus problems. In reality, I am inclined to think that inexperienced photographers, “Pixels Peepers”, and inquisitive hobbyists, influenced by the available internet information, are finding problems where there are none.

If a particular lens consistently gives out-of-focus results, when all other lenses used with the same DSLR are okay, you might have a focusing problem with that particular lens. If most of the pictures taken with the same DSLR, but with various lenses, are out-of-focus, you might have a DSLR camera-focusing problem. That alone would not mean that the lens or camera has a focusing problem, it could be the photographer’s error.

However, similar results time after time could be the first hint that you might have a focusing problem. Perhaps a logical next step would be to test the lens in question under a controlled environment. A controlled environment could be where there is no wind, with the camera set on a tripod, and with good lighting. An auto-focus testing chart could be used, preferably one approved by the manufacturer if they have one available. I do not believe that manufacturers have an AF checking chart available to the public. That is the primary reason I took it upon myself to design one. After reading every blog and information about the subject on the internet, after reading comments from the readers of my blog site and threads on various forums, I deducted that one chart could not do it all.

Three charts were designed because the minimum focusing distance varies from lens to lens. The smaller chart (Chart–1) works well for close-up lenses and lenses that have macro capabilities. The medium sized chart, (Chart-2) works well for normal lenses, say 30mm to 100mm, which have a minimum focus distance needing a target a little bigger than Chart-1. The third chart (Chart-3) is for lenses that cannot focus very close. One could keep enlarging the last chart, but I believe that the three charts attached herein will be functional for the majority of lenses. There are various opinions whether a chart should be viewed at 45° from the lens centerline axis, or at 30°, or any angle or even flat.

The reality is that it should work at any angle between 1° and 99°, but 45° is the easiest to read. Chart-1 and Chart-2 were design for viewing at 45° from the lens’ centerline axis. The measurements on the viewing surface were corrected for accurate reading when viewed at a 45° angle. The Charts could have been designed for viewing at 30°, giving more viewable depth of field for both front and back. However, I opted for the 45° because the charts could fit on a 8 ½” x 11” standard sheet of paper (Letter size).

The two smaller charts were designed so that they can be cut and taped together in a way that they can stand at a 45° angle when placed on a table, desk, or flat surface. The camera / lens is then leveled and preferably positioned on a tripod so that the lens’ centerline is aligned with the center of the chart. Place the lens as close as you can to the center of the chart target while it can still focus on the intersection of the black / white section, then back it off just a little. Position the large chart flat (horizontally) and the camera / lens angled at 45° from the chart.

Next, move the camera / lens angle slowly downward until it auto focuses. At that point, you know that you are focused on the intersection of the black / white portion of the chart. That is the center of the chart. The measurements (Metric on the left and English on the right) are at zero on both sides of the chart horizontal centerline.

Take the picture and look at the results. The center target line (00) should be perfectly clear while the top and bottom target lines and text should get increasingly and proportionally out of focus. The top target lines represent the back focus area while the bottom target lines represent the front focus area. Repeat this test several times to make sure you have done the test correctly. If the center target line is in focus, but the front and back target lines are not proportionally getting out of focus, there shouldn’t be any serious problems with the lens. Remember that this test is done with the lens opened at the maximum aperture and that the depth of field will increase with smaller aperture. Most of the lenses have a “sweet spot which is usually 1 to 2 stop smaller than the maximum aperture.

Therefore, you should only be concerned if the center target line is not in perfect focus while either the back or front lines are. Sensors are either vertical, horizontal or cross type. Most DSLRs now use cross type sensors, check your camera manual. Vertical sensors detect the sharpest horizontal contrast within its area of coverage and lock the focus on that point. Alternatively, the horizontal sensors detect the sharpest vertical contrast within its area of coverage and lock the focus on that point. You guessed it; the cross type sensors detect the highest vertical or horizontal contrast and lock the focus on that point. Since we use the center focus point of our camera, which is usually a cross type sensor, our chart was deliberately designed without any vertical lines in the center so that the focus can only lock at the intersection of the black and white portion of our target.

Note that in your viewfinder, you should see an illuminated point showing the focus point. The cross sensor is not necessarily dead center and in perfect alignment with the illuminated focus point. It merely shows you the area of the sensor, but is not an exact focus point and the sensor will only lock on the point of maximum contrast. Use ▲ ▼ to turn the AF Adjustment On or Off. When choosing On, press ► and select if you want to adjust the lens attached or all the lenses ▲ ▼.

Choosing Apply One would correct the current lens attached and would keep the results in memory. Choosing Apply All would apply the corrections to all lenses mounted on the camera. The camera can retain settings for up to 20 different lenses. Using the rear rotary dial, you can adjust the values from minus (-1) to minus (-10) and plus (+1) to plus (+10). You can reset the camera to the factory defaults anytime by navigating down ▼ to Reset and confirm Reset.

DisclaimerAlthough the Charts have given me good results, you should fully understand how they help analyzing the Auto Focus accuracy. Read the above paragraphs several times until you completely grasp the procedures. You can adjust the focus of all Pentax lenses, as they are non-permanent changes.

You can reset the Auto Focus to factory defaults at any time. As for the other Pentax camera models that do not have the “AF Fine Adjustment”, you should only have a Pentax trained technician adjust the Auto Focus of your lenses or DSLR cameras.

During an eye test, eye doctors use eye charts to measure how well you see in the distance, compared with other human beings. If you haven't established one yet,.The classic example of an eye chart is the Snellen eye chart, developed byDutch eye doctor Hermann Snellen in the 1860s. There are many variations of the Snellen eye chart, but in general they show 11 rows of capital letters.

The top row contains one letter (usually the 'big E,' but other letters can be used). The other rows contain letters that are progressively smaller.Download a.During an, your will ask you to find the smallest line of text letters that you can make out, and ask you to read it. If you can read the bottom row of letters, your is very good. What does '20/20' mean in an eye test?In the United States, the standard placement of the eye chart is on a wall that's 20 feet away from your eyes. Since many eye doctors' offices don't have rooms that are 20 feet long, in a smaller room the eye chart may hang behind the patient chair, using mirrors to make it appear in front of you at a simulated distance of 20 feet. How a Snellen eye chart and a 'tumbling E' chart might look at your eye doctor's office.

The tumbling E chart tests the visual acuity of young children and others who can't read letters aloud.20/20 vision is considered 'normal' vision, meaning you can read at 20 feet a letter that most human beings should be able to read at 20 feet.Eye charts can be configured in various ways, but generally, if during an eye test you can read the big E at the top but none of the letters lower than that, your vision is considered 20/200. That means you can read at 20 feet a letter that people with 'normal' vision can read at 200 feet. So at 20/200, your visual acuity is very poor.In the United States you are considered ' if your best-corrected visual acuity (meaning, your best distance vision with eyeglasses or contact lenses) is 20/200 or worse.To get a driver's license in most of the United States, your best-corrected visual acuity must be at least 20/40.Usually the 20/20 line of letters is fourth from the bottom, with 20/15, 20/10 and 20/5 below that. Not many people have 20/10 or better visual acuity, but many animals do, especially birds of prey, which have been estimated to have an acuity of 20/5 or even better. 'Tumbling E' eye chartIn some cases a standard Snellen eye chart cannot be used. One example is when the person having the eye test is a young child who doesn't know the alphabet or is too shy to read letters aloud. Other examples include when the person is illiterate or has a handicap that makes it impossible for him to cognitively recognize letters or read them aloud.In these situations, a modification of the Snellen eye chart called a 'tumbling E' chart may be used.

C Media CMI8738 Drivers Download. C-Media Drivers Audio Drivers Sound Card Drivers. Download the latest C Media CMI8738 driver for your computer's operating system. All downloads available on this website have been scanned by the latest anti-virus software and are guaranteed to be virus and malware-free. 'CMI8738/C3DX PCI Audio Device for. This package contains the files needed for installing the aSound CMI8738 4CH/6CH Audio driver. If it has been installed, updating (overwrite-installing) may fix problems, add new functions, or expand existing ones. Even though other OSes might be compatible as well, we do not recommend applying this release on platforms other than the ones. Cmi8738-6ch pci sound driver.

The tumbling E chart has the same scale as a standard Snellen eye chart, but all characters on the chart are a capital letter 'E,' in different spatial orientations (rotated in increments of 90 degrees).The eye doctor asks the person being tested to use either hand (with their fingers extended) to show which direction the 'fingers' of the E are pointing: right, left, up or down.Studies have shown that visual acuity measurements using a tumbling E chart are virtually the same as those obtained from testing with a standard Snellen eye chart.Download a. A Jaeger eye chart contains several blocks of successively smaller text, generally ranging in size from J10 (large print) to J1 (very small print).The original Jaeger eye chart was developed in 1867 and contained seven paragraphs, each printed in a successively smaller font size.

The smallest paragraph you could read when holding the chart approximately 14 inches away determined your near visual acuity.Since then, there have been several modifications of the Jaeger chart (or 'Jaeger card') by different manufacturers. Unfortunately, modern Jaeger charts are not standardized, and the actual letter sizes on different Jaeger cards might vary slightly.The type scale on a modern Jaeger eye chart usually ranges from J10 (approximately 14-point type for Times New Roman font) to J1 (approximately 3-point type, Times New Roman). Some Jaeger charts have an additional paragraph labeled 'J1+' that may be even smaller than the J1 block of text.The J1 paragraph on a Jaeger card typically is considered the near vision equivalent of 20/20 visual acuity on a distance eye chart. On some Jaeger cards, the J1+ paragraph is the 20/20 equivalent. Common newsprint generally ranges in size between J7 (10-pt type) and J10 (14-pt type), which are the equivalent of 20/70 and 20/100 on a distance eye chart.A Jaeger eye chart may be used in two different ways, depending on what your eye doctor is trying to measure:.The chart is held at a specified reading distance (such as 14 inches) and you are asked to read the passage with the smallest type you can see.The chart is moved forward and back until you are able to read a certain type size.Download a.

Eye chart limitationsEye charts measure visual acuity only. They do help your eye doctor figure out whether you need prescription or for your distance vision. And they help the Department of Motor Vehicles to determine if you are required to use eyewear for driving, or if you shouldn't drive at all because you are legally blind.