Macro lenses are those which can focus unusually close, providing large reproduction ratios (e.g. To find out more information, consult the USB dock page. In 2013 Sigma introduced our Global Vision lens line along with the USB dock, an accessory sold separately allowing you to calibrate the AF Data of any Global Vision lens. During the Warranty period of the product (subject to warranty eligibility), there is no charge for this service and we cover the cost of the return 3 day ground shipping back to you.
This will be done within a 48 hours of receiving your equipment in our headquarters 15 Fleetwood Ct. If this feature is not available in your camera’s menu we will ask you to send the lens to us and we will rewrite the AF Data to accommodate for the variation in your camera’s viewfinder focusing system essentially, calibrating your lens to your camera. If you are experiencing front and/or back focusing issues, we urge you use the “AF fine tune” or “Microfocus Adjustment in your camera’s menu to calibrate your lens to the camera. This is a quick solution to this situation. The issue of front and/or back focusing, most likely, comes as a result of the viewfinder focusing system which varies in each and every camera. In the majority of cases, there is nothing wrong with your lens each lens is manufactured in exactly the same way and adjusted on an optical collimator which is used to calibrate the lens, check if all elements are aligned optically and to set elements at the proper focus.
Please do not panic and do not return your lens. However, the histogram distribution of a well-exposed image will vary greatly depending on the subject. A histogram with a fairly even distribution of pixel values usually indicates that the image is well exposed, with good contrast. When the histogram runs off the right side, the image will have many white pixels-either because the image is overexposed or because it is a bright scene such as the beach or snow.
When the histogram is higher on the left side, the image is mostly composed of dark pixels, causing it to appear dark-either because the image is underexposed or because it is a dark scene such as night shot or sunset. By examining the histogram you can gauge the over-all exposure of an image. The vertical axis shows the proportion of pixels at each level of brightness.
The horizontal axis shows the brightness level (from 0 to 255), with darker pixels towards the left side and brighter pixels toward the right. A histogram is a graph depicting the distribution of brightness values in the image.
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