The technician would then adjust those elements that could be adjusted until the lens was properly centered. If an element was decentered the chart would flare or be distorted in one direction. It shined a star chart or a chart of concentric circles through the lens.
ZEISS SIEMENS STAR CHART DOWNLOAD MANUAL
The Way It Used to Beīack in the days of film and manual focus lenses, most repair shops had a centering collimator. But if the lens doesn’t have a reputation for soft corners, it may well be that the copy in question is decentered. Sometimes that’s just how the lens is designed. But one common issue people ask me about is a lens that seems OK in the center but is very soft in the corners. Unfortunately lenses are too complex for that. It would be nice if we could say “a decentered lens looks like this” and “a tilted lens causes that”. Nikon Z fc, Nikkor Z 16-50mm, Nikkor Z 40mm f/2, Nikkor Z 28mm f/2.8 (SE), Nikkor Z DX 18-140mm, Voigtlander 35mm f/1.2, Voigtlander 23mm f/1.Lens with a Poor Spacing of a Central Element I was able to exchange the lens for a better copy, and although I have not run across any decentered lenses since then, it taught me a valuable lesson I came across the test and it confirmed significant decentering of that lens to the upper right as I had observed. This became habit after my purchase of a new copy of a Sigma 30 mm f/1.4 EX DC HSM several years ago which seemed to focus more towards the upper right of the image. One of the first things I do when acquiring a new lens is to perform a decentering test. If there is decentering, the black center will be skewed to a position other than the center, and the shape of the donut will no longer be symmetrical. If there is no decentering the center of the chart should show a round black dot in the middle of a round and evenly shaped white donut. Make sure you don't AF before taking the image. But if the lens is decentered or significantly tilted the center blur will ‘flare’ out in one direction or another as you defocus.Īs indicated, manually defocus a bit on the center of the star chart and take an image. If the lens is in proper alignment and pointed directly (lineup isn’t critical, you can eyeball it) at the star, the white and black circles remain circular as they blur. If you manually defocus the lens just a bit, the star rays and the white and black circles in the center blur, of course. It should give you a good idea whether or not your lens is decentered. You can display the chart on your computer monitor, and following their instructions, which I have pasted below.
ZEISS SIEMENS STAR CHART DOWNLOAD DOWNLOAD
You can download the Zeiss Siemens Star Chart by selecting and saving the image to your hard drive. It could be a decentering issue, but you can test it yourself. Pine needles might not be the best thing to go by but, looking at the attached image, I can really notice the softness at the top right corner.ĭon't notice it so much at the bottom left in this smaller image but it is soft.
The center focus point included the eye, the widest part of the black to the right of the eye and some of the blue below the black. Normally at 200mm, using evaluative metering, center point focus, AI Servo.Ĭropping the image gets rid of the softness and I'm left with what I want but, just curious as to what's happening at the corners. Shooting handheld but resting the lens on a window frame. I'm above and shooting down on the birds. I'm shooting birds that are on the ground and I'm noticing the grass, leaves, etc, are soft/blurry in the top right and bottom left corners while they appear more in focus/sharper in the opposite corners. I'm thinking that if I'm the cause of this, then wouldn't all four corners be soft/blurry? I've been using it quite a bit lately and whether it's due to my technique or the lens itself, I've noticed that the top right and the bottom left of corners of a few images are soft/blurry. Is this particular lens known to have soft corner issues?
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