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Introduction
The composite images on this page illustrate the lens performance of the Minolta A1. The Xtra-Fine JPEGS were produced in-camera, whereas the "RAW" images were converted using Minolta's RAW converter as included in Dimage Viewer.
All are presented with equal magnification to make interpretation a bit easier.
The composite graphic on the right is of the camera's lens performance at F4.0 for four popular focal lengths. I suspect that the 108mm shot was slightly out of focus as you cannot see any grittiness showing between the lines. Other tests and photographs taken at this focal length do not show any more loss of resolution than any other focal length. What is surprising is how sharp the lens remains at the 200mm equivalent focal length. Overall, the lens has no problem focal lengths at F4.0 and this particular aperture appears to be the "sweet spot" for the lens.
Two sets of tests follow. The first is a comparison at the 50mm equivalent focal length and the last one is a comparison at the 28mm equivalent focal length.
My observations are that the in-camera pictures have less overall noise, but the processing engine performs some USM sharpening even in the "soft" setting. This particular USM sharpening is puts halos around high-contrast items. I have also found that when the sensor is noisy due to warmness (hot summer day or extended operation) or higher ISO setting are used, the USM will halo and increase the pixel noise in the image. As always, when maximum image quality is desired you just shoot RAW.
Stopping down the lens increases DOF but results in a loss of resolution due to diffraction. The F7.1 pictures illustrate the slight softening of the image. Yet, none of the images are problematic.
The bottom two frames in each test, along with the upper-right frame illustrate the in-camera sharpening effects. I recommend shooting JPEG, Xtra-Fine, Soft as the "normal" non-RAW format.
In-camera TIFF files (not shown) have exactly the same look at JPEG, Extra-Fine. They are passed through the processing engine before storage. They are NOT the same as RAW files.
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