Lens test chart PDF

Camera lens test chart pdf Part 6 - Lens Testing for resolution, chromatic aberration and distortion Probably the most frequent complaints or reasons to worry about the lens is that it is not sharp, but what does it mean? Well, if you're shooting a static object with a camera and a lens on a tripod, it probably doesn't mean much Lens Testing. Adjusting Era Lens Test Target Colour Chart Tv Vector Image. Te148 A Lens Focus Test Chart 36 Sectors 16 9 Reflectance 3nh Colorimeter Gloss Meter Color Light Box Spectrophotometer. Reflective Transmisive Era Lens Test Chart 16 9 72 Sectors Reflectance Ye0161. Zeiss 1849 755 Star Test Chart the lens and object planes for the 1:20 magnification. Then I check the size of the individual test chart images on the ground glass with a caliper and adjust the distance until I have the right value, then I center the image. Then I remove the lens, put the Zig-Align 4x5 main mirror in the camera back and hold th The alternative is to do it on the cheap: take the PDF file, print it in an appropriate size, download the code, and start testing. I think some people have posted raster images (e.g. JPEG files) of the chart on the Web; the outline description here should produce a better test chart, as it isn't limited to pixel-level resolution. DISCLAIME We are not claiming that our test charts are scientific or as rigorous as a properly designed and printed chart, but what it does is give you a practical idea of how your lens performs at different apertures and focal lengths. The Photography News test chart comes in two sizes for free download, A3 (42×29.7cm) and A2 (42×59.4cm). Size-apart.

Stand the focus chart on a level surface. Put your camera on a tripod and adjust it so it's level and pointing at the centre of the focus chart. The distance between the camera and the chart should ideally be around 50 times the focal length of the lens - for example, with a 50mm lens you want to be 2.5 metres away from the chart 3. Shot down a few myths about how the focus test works. 4. The test chart itself is unchanged from version 2.0. V2.0 (12 June 2004) This is a major release, hence the change to version2.x. The test chart has been completely redesigned. It is now much easier to use and it produces more detailed information

How to Test the Backfocus of Film & Video Cameras | The

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  1. Home > Learn > Lenses > USAF Lens Testing. Lens Testing with the USAF 1951 Chart. One way to test your own lenses is with the USAF 1951 lens testing chart. The best way to do this is to download a high resolution file of the chart from the link at the bottom of the page, and print the file out at about 3x3 inches in size on photo paper at your printers highest resolution (with many printers.
  2. Some, like the ISO 12233 chart and USAF 1951 Resolution Test Chart, will come up on most web searches. Personally, I located the highest-resolution chart I could download and then I had it printed on photo paper at a big box store at 20 x 30 and dry-mounted on foam core
  3. Free ISO 12233 Lens Test Chart. Oct 20, 2004. Download this really nice chart at measurebate your lenses to your hearts content. Its a great quality PDF. Since it is vector based and not rasterized, it will scale nicely to any output size. Have fun
  4. VALUES IN 100X LINES PER PICTURE HEIGHT This test chart is for use with ISO 12233 Photography - Electron ic still picture cameras - Resolution measurements Chart Serial No. _____ Printed by ____
  5. e your Angle of Astigmatism at the moment before you start this practice session. Instructions: 1. Attach the Far Chart to the wall with the center dot at eye level, stand 3 to 4 feet away and hold the Near Chart in your hand 12 to 16 inches.

The USAF 1951 lens test chart (on the right; Robert Monaghan's detailed printable PDF version) and its variants have been a standard for half a century.But it is unsuited for computer analysis because of its fragmented arrangement, and it is poorly suited for visually estimating MTF (Modulation Transfer Function, which is synonymous with spatial frequency response; see Understanding image. Analyzing Lens Testing Chart Images. The images you shoot can be analyzed for sharpness and chromatic aberration quite easily. The numbers on the lens testing chart represent the line pairs per mm (lp/mm) values of the test patterns they are next to. These patterns should be pretty accurate down to the set marked 5.0 DXOMARK's comprehensive camera lens test result database allows you to browse and select lenses for comparison based on their characteristics, brand, price, lens type, lens size, focal range and aperture. You can also select a camera to see the results for all the lenses tested on it users, who wonder whether the old lenses are superior to current Leica M lenses in terms of contrast range, contour sharpness and resolving power. With his knowhow and the experience of numerous test series, he juxtaposes comparable lenses and their performances. In addition to factual explanations, he also presents charts an Fig. 1 ISO 12233 Test Chart as I use it. The inset parts are at 1/4x size. The numbers mean x100 LW/PH for the large part and x400 LX/PH for the small parts, both applicable if the chart spans the entire picture height. Some labs use a variant of the original chart with scales going to 40 rather than 20. But this i

Lens Als. Focus Chart Im. Zeiss Siemens Star Test Chart 1849755 Adorama. Printable Siemens Star Targets. Siemens Star Chart. Lens Als. Abelcine Resolution Ysis Charts White Paper Tutorials S Knowledge. Siemens Star Png Transpa Images 136595 Pngio. Resolutions At All 9 Siemens Star Chart Locations According To Figure Scientific Diagram The focus chart is located right across from the camera. The distance between the camera and the wall depends on the focal length of the lens you are testing. If you are using a 50mm f/1.4 lens, then the distance between the camera and the test chart should be approximately 5 to 7 feet (1.5-2 meters)

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I tested lens on this chart with all focall lenghts and in 5 diferent lenghts, 0.45m, 0.7m, 1.00m, 2.5m, not infinity and summary of test is when i increase distance from target there is more and more backfocusing, at 2.5 m is eaven hard to find focus spot a test chart at a test distance of 4 ft, an actual distance of 4 ft 1' is measured. Due to the table on page 14, a silver shim 0.013 mm must therefore be added to the total thickness of the shims The first thing you need is a lens calibration chart or focus pyramid. It works best with a few minutes in a quiet environment. You can get the lens calibration chart at a reasonable price. There are more expensive options, but this works well for focusing lenses. We use the DSLR KIT Lens Focus Calibration Tool, and it works perfectly

ARRI FOCUS CHART Purchase a focus test chart. If you have some money burning a hole in your pocket, you could always buy a focus chart. A quick Google search reveals that these charts vary in price significantly. A cheap focus chart card may only cost you about $14, but some of the higher-end options cost over $1,000 The star chart in the center of the test target makes it very easy to focus in live view, but first examine the pattern of the chart just out of focus at maximum magnification. On a well aligned lens the star should blur into a fuzzy oval like three of the images below do

Lens Test Chart Pdf - Best Picture Of Chart Anyimage

chart. If you use eyeglasses or contact lenses for driving or other distance vision tasks, wear them during the test. 1. Place the chart on a wall or easel 10 feet away. 2. Cover one eye with your hand, a large spoon or some other item that completely blocks the vision of the covered eye TEST YOUR EYES HERE click on the print button as seen below. This will bring up a print dialog. In this dialog, set the Page Scaling to None. Without glasses read the chart to the right from a distance of approximately 15 (40cm). Read down the chart until you reach a line that you cannot read clearly and the number on the right is the lens. The PLI Lens Test Chart is available from Morgan & Morgan publishing. If the PLI Lens Test Chart is not available to you, the same results can be tested by duplicating the test pattern below. Placing copies of this test pattern in the center of the field of view as well as the edges of the field of view will allow you to test for basic. Quick Mtf Testing Procedure For Era Lens. Lasersoft Usaf 1951 Test Chart Scanner Resolution Mounted Slide For Determining The Of Your Flatbed Or Transparency Scandig Gmbh. Usaf 1951 Determination Resolulution. T 20 Usaf 1951 Chart Standard Layout Specifications Part No Grouped By Substrate Material N Cg P exactly in the test of the lens. Field angle positions, conjugate ratios, spectral regions, and image plane architecture can all be modeled in the test of an optical system. For example, the characterization of a double Gauss lens at finite conjugates can be easily performed and compared to design expectations or application requirements

Chapter 7 Lenses Pathology 464 Light Microscopy 2 Figure 7.2 Charles Spencer figure 7.1. The 3 X lens has an angular aperture of 14˚ compared to 110˚ for the 95 X lens. Some people thought that magnification was the sole contributor to resolution. Charles Spencer (figure 7.2) - a lens Ophthalmic Lens Materials Lecture -2-1- Ophthalmic Crown is made of 70% Silica (sand), 14-16% Sodium Oxide, 11-13% Calcium Oxide and 1-5% of Potassium, borax, antimony and arsenic Ophthalmic Crown is used for the majority of single-vision glass lenses available toda 2. Test your visual acuity with correction (contact lenses or glasses). 3. Test one eye at a time. Start with the right eye, covering the left one without pressing on it. Then, examine the left eye by doing the opposite. If you are using correction glasses, you can cover the eye with a sheet of paper. 4. Read the letters from the largest to the.

ISO 12233 Test Chart - Cornell Universit

Free lens testing chart download - Photography New

Fiddleheads with Resolution. FiddleHeads features a unique double spiral designed with help and testing from Steve Lucas at VER in LA. FiddleHeads produces what has been described as a visual pop at the precise point of optimum focus. Includes framing lines for 2.35, 1.85 and 90% of 1,85. with corner resolution wedges up to 1600 TV LPPH Lens geometric measurement. Lens distortion can have a different appearance in the image like barrel and pincushion distortion. We report the Lens Geometric Distortion value (LGD) and measure it with the TE251 test chart. The iQ-Analyzer software detects each cross with subpixel accuracy, calculate the ideal grid and calculate the distance between current location and the location on the ideal. Calibration chart images must be captured by printing a calibration chart PDF file and shooting the printed chart with the camera body and lens combination that you wish to generate a lens profile for. For optimal results with captured calibration chart images, please read the companion document titled Calibration Chart Shooting Guide for.

AbelCine Resolution Analysis Chart FAQ | Tutorials

Lens Reviews Our lens reviews are based on detailed testing in an optical lab and real world shooting. We also provide hundreds of user reviews from photographers like yo Below is a MTF chart for the AF-S DX NIKKOR 35mm f/1.8G lens. When measuring a lens' performance for a MTF chart, Nikon tests are carried out with the lens at its maximum (widest) aperture. The contrast of the Sagital and Meridonial line pairs at various points from the lens' center are read and plotted on the chart Focus Test Chart Printable Download And Print. Some folks havé found that, particuIarly when using thé kit lens, somé of their imagés are not correctIy focused. This problem manifésts primarily when shóoting close-ups át wide apertures. After doing Iots of research ánd testing, I producéd a simple ánd effective test thát quickly. a. Verify lenses: lenses should have their ink markings and frame should be adjusted. If ink markings are missing, retrace them from the micro-circles using the appropriate di-test card. • the fitting cross should be at pupil center when eyeglasses are on the wearer. • adjust the frames to raise or lower the fit if necessary b

A 1951 USAF resolution test chart is a microscopic optical resolution test device originally defined by the U.S. Air Force MIL-STD-150A standard of 1951. The design provides numerous small target shapes exhibiting a stepped assortment of precise spatial frequency specimens. It is widely used in optical engineering laboratory work to analyze and validate imaging systems such as microscopes. When possible, print directly from SVG or PDF files. Follow steps 1-4 above: Install Inkscape, create the SVG test chart, save it, open it in Inkscape, select the chart image, then set the page and image size using the Document Properties window and image size using the handles at the corner of the chart image Using a special test chart (.pdf supplied), measure the point of sharpest focus relative to a reference point, i.e., measure front- or back-focus in DSLRs; Measure the MTF (sharpness) of your lens across the field of view; Works with many image formats, including JPEG and various raw format

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Simple Test To Check The Lens Sharpness. Here's a simple test. Remember to perform this test with a static subject. That way you can be 100% sure on the results you get. Follow these steps: Place your camera and lens setup on a sturdy tripod. Place an object (like a vase, flower, toy, etc.) at the minimum focusing distance* (MFD) of the lens If you wanted to test this further to see just how sharp your lens is then I recommend you use live-view, zoom in to the max and take some manual focus shots just to see how sharp your lens. 428 [1], A test of lens resolution for the plio- tograpliQr, was published. This Circular, in ad¬ dition to giving detailed instructions for perform¬ ing a lens resolution test, also contained 12 carefully made test charts for use in the test. These test charts were made by the Bureau of Engraving and Printing in accordance with de Perform a lens sweet spot test. Once you have your camera set up on a tripod, performing a sweet spot test only takes a couple of minutes. To begin, put your camera in Aperture Priority mode, then compose your shot and take photos at varying apertures. Start with a shot at the widest aperture, then rotate that main dial a couple of times (to. The Leica Q2 is an impressively capable fixed-lens, full-frame camera with a 47MP sensor and a sharp, stabilized 28mm F1.7 Summilux lens. It's styled like a traditional Leica M rangefinder and brings a host of updates to the hugely popular original Leica Q (Typ 116) that was launched in 2015

How to Test Your Lens B&H Explor

  1. An eye chart is made up of rows of letters that vary in size. Although each row contains letters that are the same size, the size of the letters in each row gets smaller from the top of the chart to the bottom. When you take an eye test, you will stand a certain distance away from this chart and read each row of letters
  2. Feasibility Study Conclusions. The above table shows that for an actual testing distance of 50x the focal length (designed for 25x the focal length), the worst-case scenario, a 4/3rds camera with an f/1.2 lens, the test target can vary no more than about 1/8 of an inch
  3. Photograph the chart using glare-free even lighting (±5%, which should be easy to achieve since the chart is relatively small), as described in Building a Low-Cost Test Lab or How to test lenses. Save the image in any one of several high quality formats, but beware of JPEGs with high compression (low quality), unless you are testing for JPEG.
  4. The T Test Chart software turns a standard PC into a powerful and versatile Test Chart for Optometrists, Ophthalmologists, Orthoptists and other eye care professionals. Test Chart 2020 offers an unrivalled suite of test charts and vision tests, binocular vision tests and refraction stimuli. Simply install the software on your PC, mount a.
  5. 2.ChoiceofCriterionforJudginga Lens Thequestionofhowtoratetheperformanceof alensisnecessarilycomplex,dependingasitdoes upontheuseofthelens.Thecomplexityofthe.
  6. Lenses that Lens Align told me were out by as much as +/- 15 were only out +/- 2-3 with this method. That went across the whole line up of bodies and lenses. I am not sure if I just didn't set up the Lens Align correctly or what but to pay nearly $90 for a tool that (if I set it up correctly) gave me flawed results

Free Lens Focus Chart PDF. Print it out, or display it on your laptop screen The test table contains slanted-edge areas. By analyzing such areas, Quick MTF can calculate the device's resolution, chromatic aberration, and noise. The technique is described in the ISO 12233 standard and fully implemented in Quick MTF. Image analysis using the modulation transfer function (MTF) provides more accurate and objective.

If after all the above steps your photos are still not razor sharp, the lens of your DLSR may need some calibration. A simple way to determine whether the autofocus of your lens is accurate is to test it on a focus chart. A variety of easy-to-make DIY charts are available for free download online. We tried the following Camera-to-subject distance should be no less than 50 times the focal length of the lens. For a 50mm lens, that would be at least 2.5 meters. Set the lens for AF and the camera for One-Shot AF, and manually select the centre focusing point. Shoot at the maximum aperture of the lens via manual mode or aperture-priority In the field of video production, where it is often called a back focus chart, the Siemens star is widely used to adjust the back focus of removable lenses.It is also used during film or video shoots to help setting the focus in special situations.. Siemens stars are similar to the sunburst pattern used as a background in graphic design, as in the Japanese Naval Ensign, Russian Air Force flag. The MTF chart or graph uses two axes. The horizontal axis (x-axis) shows the distance between the measurement point and the centre. The '0' in the bottom left-hand corner is the centre of the lens. The other numbers represent the distance, given in millimetres The test in this blog is a more general optical test while the star chart is only for decentering. People are using decentered as a general term when in fact lens elements can be decentered, tilted or spaced incorrectly

Free ISO 12233 Lens Test Chart: Canon SLR Lens Talk Forum

Lens testing - Norman Kore

Eye Health: 4 Eye Test Charts and How They Work One's eyesight is an integral part of daily living. From vision to detecting colors our eyes are responsible for so much of life we take in each day. In fact, we identify up to 80% of all impressions by means of our sight Repeat this and take atleast 5 images per test. LENS CALIBRATION ADJUSTMENT: Leaving the camera in position, remove the memory card and view the images on a large high resolution monitor at 100% magnification. The number 0 should be the sharpest and most in-focus point in the image. If the focus plane is infront or behind, adjust the micro. A Reading Test Chart can be used to determine the lens strength (dioptre) of the reading glasses you need and a PDF chart can be downloaded here.The chart is shown below and instructions as to how to use the chart are included in the download

Camera Lens Testing- Sharpness, Chromatic Aberration and

  1. Image formation for mirrors and lenses Type Focal length f Object distance s Image distance s' Character Orientation Size Concave mirror/ Converging lens f > 0 s > 2f f < s' < 2f real inverted reduced f < s < 2f s' > 2f real inverted enlarged s<f s'<0 virtual upright enlarged Convex mirror/ diverging lens f < 0 s > 0 s' < 0 virtual.
  2. With moveable near vision chart: Bring the near vision chart in towards the subject until it is only just legible,the amplitude of accommodation is the reciprocal of this distance. For example:nearest reading distance = 0.50 m, amplitude of accommodation = 2.00 D. With fixed near vision chart: • Position the near chart at 40 cm (16 in
  3. The tumbling E chart features the same scale as a standard Snellen eye chart, except all characters on the chart are a capital letter E, rotated in different increments of 90 degrees. During a tumbling E test, the eye doctor will ask the person being tested to use either hand (with their fingers extended) to show which direction the fingers.

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STEP 2: TEST TIME. Hold the printed chart 14 inches from your face. Go ahead and wear corrective contacts if you have them, but no glasses -- that's cheating! Start reading at the top line and work your way down. The first line that appears blurry will have your ideal magnification listed to the left The Enhanced ISO12233 digital resolution test chart comes in 3 sizes and can be printed on matte, luster, or glossy photographic paper. Matte or Luster is recommended for larger chart sizes where it can be hard to uniformly illuminate without specular reflections. Density Values: Black Areas: 1.6. Dark Gray Areas: 1.1. Light Gray Areas: 0.

Zeiss Siemens Star Chart Pdf - Best Picture Of Chart

Andy&#39;s Handy Focus Calibration chart | Downloaded it here

- Rays that cross at the focal point of the lens are considered to have an infinite amount of vergence. Therefore, rays that are parallel (have no crossing point), have a vergence of zero. - Converging lenses have real/inverted images that are on the opposite side of the lens from the object And there you have it, the GhettoCAL. Here's a blown up image of the Nikon D3 and Nikkor 28-105 f/3.5-4.5D combo at 105mm: it looks like the lens front focuses slightly. Remember, these targets. Mount your camera on a tripod and place it at a certain distance right across from the chart, depending on the focal length of the lens. The developer recommends to aim for between about 25x - 50x the focal length of the lens in millimeters, so if you are calibrating a 50mm lens, you should test at around 1.25m to 2.5m Worldwide, there are a variety of test techniques, methods and test charts used by different optical engineers to measure lens performance in controlled conditions. Regardless, their ultimate aim is to generate data that can be plotted on a chart and provide dealers and customers with an idea of the relative optical performance they can expect.

How to Quickly Test Your DSLR for Autofocus Issue

  1. i test target will allow for very fine, precision focusing and will help to reveal a great deal about the camera and lens in use
  2. * Print out the PDF or read directly from your screen. *If you choose to read directly from your screen, be sure the PDF's zoom setting is set to 100% before you continue. * At eye evel, read the chart from top to bottom at distance of 14 inches. The first line you have difficulty reading will list the power of lens you need
  3. Created Date: 2/25/2011 10:29:32 A
  4. Have you ever noticed your lens isn't always pin-sharp when using autofocus?This lens autofocus problem can happen because lenses can drift over time. You wa..

Shoo+ng#environment#for#the#adjustment#test 2. Camera#and#lens#seHngs 1 Preparaon % 3 Adjust% Performtestshoong 1. Shoot#images#to#check#the#AF 2. Points#when#comparing#the#images 3. Confirmthe#images Perform%AFMicroadjustment% 1. Adjust#by#lens 2. Register#the#lens#serial#number 3. Adjust#All#by#same#amount. Discovering Our Personality Style Through TRUE COLORS Outcomes In this module participants will : Discover the qualities and characteristics of their own particular personality styl Discover how the Google Lens app can help you explore the world around you. Use your phone's camera to search what you see in an entirely new way. Discover how the Google Lens app can help you explore the world around you. Use your phone's camera to search what you see in an entirely new way. Lens. Skip to Content Depth of Field Definition. Depth of field refers to the section of a photograph that appears to be in sharp focus. John Shaw's Nature Photography Field Guide, John Shaw, 2000 . The depth of field is defined as the area in front of and behind the subject that is in acceptable focus. Night and Low-Light Photography Workshop, Alan Hess, 201

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Lens calibration A beginner's guide Adob

How to Check Your Lens for Decentering A quick and easy decentering test By beholder3 in Articles and Tips on Jul 20, 2017. When we invest our money in high-quality camera lenses, we expect them to be able to capture sharp, clear photos Both resolution chart testing and field testing for sharpness and other optical qualities were performed. Here is a summary of the resolution/sharpness tests shot wide open at f/5.6 without the teleconverter and f/8 with the teleconverter. There is little to no sharpness improvement by stopping down when just the lens (without TC) is used A measure of the sharpness of vision using a letter chart. Best Corrected . Visual Acuity (BCVA) is the best vision with eyeglasses. Uncorrected . Visual Acuity (UCVA) is the best vision without eyeglasses or contact lenses. Vitreous Loss: The loss of a clear gel like material from the farthest back chamber of the eye during a surgical. All About Photographic Lenses, Modern and Old. Specifications, features, comparison, user reviews, comments, MTF-charts for lens by Canon, Nikon, Sony, Pentax.

Printable Siemens Star targets - Kasso

・The lens without built-in AF motor can only be used in manual focus mode. *5 Use the lens by setting the camera's image area. *6 Performance is not guaranteed for use with conversion adapters (mount adapters, converters, etc.) produced by other manufacturers Macro lenses Typical working distance - e.g. 0.3m for 1:1 shooting. Note that Focal length is the actual focal length of the lens (and teleconverter combination if applicable) - the sensor crop factor can be ignored. The chart below shows this visually (not to scale): 8mm 0.5m 85mm 3.5m 40mm 2m 100mm 4m 200mm 6m 400mm 8m 800mm 16 Filter lens shade selection is to be made based on the welding process, arc cur-rent, electrode size and/or plate thick-ness. Use ANSI Z49.1:2012, Table 1, Guide for Shade Numbers, to select the proper filter lens shade for both protec-tion and comfort (reduction in visible glare). Note: Filter lenses shall meet the re Also note the vertical axis (which shows the peak resolution) is different for this lens (the program automates the axis). The other three lenses peak near 800 line pairs, while the lower left lens peaks at about 600. It's significantly worse than the other lenses. Our star-chart flare did a nice job of identifying this decentered lens

High Resolution Test Patterns - Beale Corne

Zeiss Lens Data Sheets are available in PDF (Portable Document Format) file format. They can be viewed and printed using any program that can open and print a PDF file. We suggest using the Adobe Acrobat Reader. The Adobe Acrobat Reader allows you to view and print Hasselblad Historical documents in PDF format Ishihara Test. Please note that computer based color blindness tests do not give the same results as the original tests. Computer displays have only three primary colors. The colors of the printed books cannot be simulated by a display. The test can only determine red-green color blindness. Not suitable for clinical diagnosis a vision test. When it is time for your vision exam, the field office employee will ask you to read a line on an eye chart with both of your eyes open and then another line with each eye individually. If your driver license is already restricted for corrective lenses, you may take the vision test wearing your glasses or contact lenses

Eyesight Measurement Resources - endmyopiaNikkor 50mm f/1How to read an USAF1951 target? | OptoWiki Knowledge Base

36 L x 24 W, Resolving Power Chart. #83-001. $42.00. Qty 5+ $38.00 Request Quote. In Stock. ×. USAF pattern is printed in black, red, yellow, and blue to test for chromatic aberration and at 90° for testing astigmatism. Technical Information. Number of Line Pairs / mm in USAF Resolving Power Test Target 1951 isochromatic Plate (PIP) test. Passing is defined as no more than 4 errors in the 14 plate set. Note: these are the 14 number test plates - NOT the demonstration number plate or the plates with the colored trails. For details, please refer to the PIP instruction book that comes with the test. For aviation purposes, no more than two errors ar Ishihara Color Test Instructions. Plates 1 - 17 each contain a number, plates 18 - 24 contain one or two wiggly lines. To pass each test you must identify the correct number, or correctly trace the wiggly lines. Sit approximately 75cm from your monitor, with each circle set at eye level. Preferably have mild natural light and no glare on. Test Setup, Star Chart. In order to evaluate sharpness, we photograph a standard test chart (or star chart) that can be used to compare lenses to one another. The general rule is that the distance from the lens to the test chart must be 100 times the focal length of the lens. For our lens, this means a distance of 7.7 meters