Vignetting test method - Printable Version +- Opticallimits (https://forum.opticallimits.com) +-- Forum: Forums (https://forum.opticallimits.com/forumdisplay.php?fid=4) +--- Forum: Just Talk (https://forum.opticallimits.com/forumdisplay.php?fid=17) +--- Thread: Vignetting test method (/showthread.php?tid=2833) |
Vignetting test method - Xastoul - 11-24-2011 Is there different test method to measure the vignetting for a lens? Because I've check on other site lens review and they seem to end up with almost twice the vignetting value compared to here. This time I did some research just to be sure I'm not asking for something stupid... I hope I did not forget something. There are a lot of example but I'll cote only this one, Nikkor AF-S 50mm f/1.4 Ghere it get a vignetting value of .56 Ev On the other site the have a value of 1.00 Ev They are both shot with a Nikon D200 Most lens have a noticable difference, some like the Micro 40 mm , have almost the same value. Is there a reason for that? Vignetting test method - Klaus - 11-24-2011 We test the vignetting at infinity focus and using standard JPEGs (sometimes RAWs for cross-comparison) based on an evenly lit, back-illuminated test target. The displayed peak in the histogram (representing the gray value) is at the 3/4 position (we overexpose by 1-1.3 stops during the procedure). This approach is the same across all tested systems, of course. So differences between the sites can occur due to a. a different focus distance b. a different exposure characteristic c. a different S curve in the JPEG/RAW d. a different tool used for the analysis of the test data |