Jörg Krüger
Software vs. Lens Quality #1
Software vs Lens Quality
Lens correction of a Pentax K-1 on the SMC-Pentax FA* 2/24 IF&AL
Yet another pixel research project. So, what have I done here? First I took a picture of a grid with the 2/24 in RAW-format. From it I developed two different JPGs in the camera: the first one without any correction, the second one with lens correction (distortion, vignetting, lateral CA, diffraction) and color fringe correction, but without sharpening, noise reduction, etc., and then I compared them. For this I split the two images vertically through the center, the left part of the uncorrected image you can see in the upper left corner, the right part of the corrected image you can see in the upper right corner, both put together as it would be the whole picture, the yellow arrow indicates the seam.
In addition, I selected one square of the grid and enlarged it. You can see the same square of the corrected and uncorrected image on top.
Now it gets interesting: the dark part below shows the difference between the two complete images, that means, the difference of the value of each pixel is displayed by a new one. If the values of two pixels are identically, the difference is zero, so the new pixel is black. The brighter the new pixel is, the greater is the difference between the corrected and uncorrected picture. If the new pixel is colored, also the color was corrected. (Math: RGB-value(new pixel) = abs[RGB-value(pixel-pic1) - RGB-value(pixel-pic2)].)
I must admit, that I wanted to provoke a high amount of lens aberations, so I chose f2 and a short focal distance, ca. 60 cm, while the lens is designed for a focal distance of infinity of course.
You can see clearly the influence of the correction regarding distortion and vignetting. The deep darkness in the corners is just blown away. The black area in the center of the difference-view, where no correction happend, is remarkable large, but towards the border the pixels were moved a lot.
The enlarged squares on top show the treatment of the lateral CAs: not really efficient, purple and green just changed their places.
Note 1: Somewhat strange, the color fringe correction is only available when you are developing a raw-image in the camera. It is not supported, when you are taking pictures in jpg-format directly.
Note 2: Supported lenses are all DFA lenses, all DA lenses in APS-C-mode only, except some telephoto lenses, and I think most of the limited and FA* lenses, at least the better ones. Also three common FA lenses (2.8/28, 2/35, 1.4/50) are mentioned in my manual. Actually, my 2/35 is not supported, and I can use the corrections on my DA 3.5-5.6/18-55 in full-frame mode, yet I don't expect much here.
Note 3: I have firmware version 1.40.
The same checkup for the SMC Pentax DFA 2.8/100 Macro.
Software vs. Lens Quality #1
Software vs Lens Quality
Lens correction of a Pentax K-1 on the SMC-Pentax FA* 2/24 IF&AL
Yet another pixel research project. So, what have I done here? First I took a picture of a grid with the 2/24 in RAW-format. From it I developed two different JPGs in the camera: the first one without any correction, the second one with lens correction (distortion, vignetting, lateral CA, diffraction) and color fringe correction, but without sharpening, noise reduction, etc., and then I compared them. For this I split the two images vertically through the center, the left part of the uncorrected image you can see in the upper left corner, the right part of the corrected image you can see in the upper right corner, both put together as it would be the whole picture, the yellow arrow indicates the seam.
In addition, I selected one square of the grid and enlarged it. You can see the same square of the corrected and uncorrected image on top.
Now it gets interesting: the dark part below shows the difference between the two complete images, that means, the difference of the value of each pixel is displayed by a new one. If the values of two pixels are identically, the difference is zero, so the new pixel is black. The brighter the new pixel is, the greater is the difference between the corrected and uncorrected picture. If the new pixel is colored, also the color was corrected. (Math: RGB-value(new pixel) = abs[RGB-value(pixel-pic1) - RGB-value(pixel-pic2)].)
I must admit, that I wanted to provoke a high amount of lens aberations, so I chose f2 and a short focal distance, ca. 60 cm, while the lens is designed for a focal distance of infinity of course.
You can see clearly the influence of the correction regarding distortion and vignetting. The deep darkness in the corners is just blown away. The black area in the center of the difference-view, where no correction happend, is remarkable large, but towards the border the pixels were moved a lot.
The enlarged squares on top show the treatment of the lateral CAs: not really efficient, purple and green just changed their places.
Note 1: Somewhat strange, the color fringe correction is only available when you are developing a raw-image in the camera. It is not supported, when you are taking pictures in jpg-format directly.
Note 2: Supported lenses are all DFA lenses, all DA lenses in APS-C-mode only, except some telephoto lenses, and I think most of the limited and FA* lenses, at least the better ones. Also three common FA lenses (2.8/28, 2/35, 1.4/50) are mentioned in my manual. Actually, my 2/35 is not supported, and I can use the corrections on my DA 3.5-5.6/18-55 in full-frame mode, yet I don't expect much here.
Note 3: I have firmware version 1.40.
The same checkup for the SMC Pentax DFA 2.8/100 Macro.