Originally posted by audiobomber I believe the 18-250mm photo is sharper.
Look at the sky around the sails. The 18-250 is showing texture in that area that the 50mm is losing.
This is the reason why I speculated that I probably hit a better AF fine calibration for the 18-250 compared to the 50mm. The print raster actually manages to excite some moire, it appears.
However, there are plenty of areas where the 50mm image is definitely sharper. I understand sharpness to be a combination of resolution and contrast. Look at the "T-SHIRT" writing at the top right corner of the image. Less blurry with the 50mm. Look at the fine print below the fish pic tarting with "Package includes". Less blurry with the 50mm. The most dramatic difference can be seen in the writing "Kellog has introduced..." at the top left corner of the image. It looks like the blurriness of the 18-250 may come from a non-flat focal plane or corner weakness but still overall, the 50mm image is more contrasty and has less blur in many areas.
I agree with you that the 18-250 pulled out the texture better in a part of the image, but I put that down to a better AF result.
Originally posted by audiobomber At the very least, your photos are very close in sharpness.
Please have a look at the areas I pointed out. The differences are not subtle at all. I'm not saying you have this problem, but I noticed that when I view these pages with Firefox, then any differences in sharpness become totally blurred as Firefox has a wrong DPI setting for my screen and therefore resizes (enlarges) the images. When I view them with Seamonkey, 1 image pixel becomes 1 screen pixel and the differences are much easier to see. If the 800 pixel wide images on these pages look larger/smaller than a 800 pixel wide image in a photo browser with 100% magnification then resizing takes place, making it extremely difficult to still see the original sharpness (differences).
Originally posted by audiobomber The 50mm outresolves the 18-250, and there's no room for doubt.
My test result confirms this. Probably not to the extent possible, because I believe the AF calibration for the 50mm was not optimal, but the 50mm images is sharper in many ways then the 18-250 image. I agree with you that my result seems to indicate that the 18-250 shows higher resolution for some part, but the explanation "better AF result" solves this puzzle.
EDIT: One difference between our tests appears to be that you did a heavier crop than I did and only showed the centre performance of the lenses. Admittedly, my results mainly show that the prime performs much more uniformly then the super zoom.
Originally posted by audiobomber I still love the K100's image quality for most forms of photography, but with the cropping I do for wildlife shooting, there's really no comparison.
Fine. But note that I'm not discussing this point at all. What I took issue with was the quality of your K100DS shots. If even my 18-250 can see the print texture, your 50mm should have seen it all the more. Unless the AF result wasn't optimal. However, if your AF result wasn't optimal then this would explain why you obtain a result that contradicts the expectations and experiences of other forum members.
Originally posted by audiobomber You cannot compare my photo set to yours given a different subject, different lighting, different setup, different processing.
Please note that I have stated this myself. However, one of the differences is that you used the "bright" setting. Your images, using AF as I did, should therefore be sharper than my "natural" images. Also, if some of my images are sharper than yours then this suggests that either the K100DS has worse JPEG output than the K100D or that you could have obtained better results. If the latter is the case, it questions the validity of your conclusion.