ISO Test Chart. In Standards Organization adopted ISO Standard Photography Click here for a printable PDF version. ISO specifies methods for measuring the resolution and the SFR of electronic still-picture cameras. It is applicable to the measurement of both. View Account▹ · Home; BS ISO Secure PDF. ℹ Printed Edition + PDF; Immediate download; $; Add to Cart.
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Résolution et réponses en fréquence spatiale. STANDARD. ISO. Third edition. Reference number. ISO (E). This document is a. ISO INTERNATIONAL. STANDARD. ISO. First edition Details of the software products used to create this PDF file can be found. The ISO chart contains a lot of areas suitable for testing purposes. ISO Test Chart - contains a printable PDF version and several links for downloading .
Tilt the camera right or left, up or down so that the rectangle is squared. If the camera is tilted the rectangle will look like a trapezoid. Rotate the camera clockwise or counterclockwise so the top and bottom lines are perfectly horizontal. A degree or two of tilt and rotation is fine for this work unlike Imatest, where 0. The camera will need a couple of degrees of clockwise rotation and a bit of turning.
The first point is that we test with the aperture wide open. Even a badly decentered lens may look reasonably good when stopped down. If you have a question if this is happening, just walk around to the front of your setup and look into the lens barrel. 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. A badly decentered lens will blur with a flare going in one direction or another, like the image on the lower left below. This amount of flare can occur on some normal lenses, but the amount on the lower left is never normal. When you get the star sharply focused, the pattern should be circular, like the image below.
In some decentered lenses the gray circle, where the individual star lines blur together will be oval.
In other types of decentering, you may notice the more vertical stars are much sharper than the horizontal stars, or vice-versa. I suggest taking a photograph with the center both in and slightly out of focus. The idea is NOT trying to measure how well the lines resolve, especially in live view. No further testing is needed, go take pictures.
When you examine them, the corners all look a bit soft, but equally so. The second step is to zoom in on one corner and manually focus the lens to bring the corner into best focus. And by how much? Once any corner is in sharpest focus, move the cursor around to check the other three corners and see if they are all equally sharp again.
Field curvature, which is a normal part of lens design, means the corners will have a different focus point than the center. But since our alignment is square and centered to the chart, the 4 corners should all focus at the same point. As long as they do, this part of the test is normal.
In reality, there are three types of misalignment: A badly aligned lens often has more than one problem and the symptoms overlap somewhat, but we can make some generalizations. A mildly tilted element often causes two corners to be different than the other two corners.
It can be side-to-side, top-to-bottom, or opposite corners. How do we tell this is simply tilt, rather than another form of decentering? With tilt, changing focus often makes the top two corners sharp, but the bottom corners will get fuzzy or left and right, etc.
With other problems, the top two corners usually never get sharp, they always remain softer than the bottom corners. A mildly decentered lens may only have one bad corner rather than two like the example above. In that case center resolution is always still excellent, although on an optical bench or in an Imatest lab you might notice the sharpest point of the lens has moved slightly off center, away from the bad corner.
In other cases the problem affects only the horizontal or vertical line pairs, like the image below. One other interesting finding that we sometimes see in this situation: There are some lenses that will show this astigmatism-like behavior in all 4 corners. But if only 1 or 2 corners show it, the lens has issues. A badly tilted element, especially if near the rear of the lens, can make the entire image soft, even in the center.
Spacing errors, and significant decentering of an element can have the same effect.
Sometimes a decentered element leaves the center of the lens quite sharp, but all 4 corners very soft. A little common sense helps in this situation. You should expect 10X consumer grade zoom to be rather soft at the long end. Even good telephoto zooms often have soft corners at the extreme telephoto end. First and foremost is the center star target. A lens decentered this badly will almost always have a significant flare, like we demonstrated above, when just slightly off focus.
Some will even show flare at their best focus. If you examine the corners carefully they may all be soft, but one is usually quite a bit better than the others, and one quite a bit worse. Examining the thick black boxes will often show chromatic aberration at the edges and it will be of odd pattern: It might be away from center on one side and toward center at the other, etc. Obviously all lenses will be a bit sharper stopped down. Zoom lenses have to be checked at 2 or 3 spots.
Most optically challenged zooms are bad throughout the range, but there are definitely some that only have a problem at the long or short end. Because of the limitations of chart size, testing at a given focal length is only done at one focusing distance. There are lenses, although they are rare, that have problems at certain focusing distances but not others and this test might miss that problem.
But optical benches and Imatest have the same limitation; they only test at certain distances. One thing I should note: Most of these have a little bit of flare in the center even when perfectly adjusted and all 4 corners will rarely be completely identical, although they should be close. All four corners may be blurry, but some corners will be worse than others, or the horizontal and vertical resolution will be different.
Less severely decentered lenses may look fine in the center and may, or may not, exhibit center flare. They will show differences in the corners that are readily apparent, however. We retest all of those on an optical bench and rarely find one that was actually OK. We also run QA checks using Imatest or the optical bench on lenses that have passed this optical testing.
When we recheck these lenses, we do find that about 0.
However, if we repeat this optical chart test on those same lenses, they almost always fail the repeat test. In other words human error, not the test itself, let the bad lenses pass.
There are lots of other ways to test lenses, of course. And testing 8, to 9, lenses a month, experience is one thing we have a lot of.
Someone who has experience servicing high-end lens would be best. Most of our repairs are middle to high-end equipment to Professional customers. Our Nikon lens volume has more then doubled in the last year. Knowledge of D-SLR repair would also be helpful.
They are also authorized on Canon IS-Series lenses. Hailed as one of the optic nerds here, I enjoy shooting collimated light through 30X microscope objectives in my spare time.
When I do take real pictures I like using something different: Max, LOL. As the GH3 comes in some kit options it includes info on pulling the included lenses apart in considerable detail. Contact Details Phone: Integrated State-wide transport planning and major transport infrastructure projects. Port and Environs Strategy Esperance clean-up and recovery. All Contacts. Bringing together the Department's cycling and walking activities and behaviour change programs. Safe Active Streets Program.
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