Originally posted by abacus07 Is it common for lenses to go from sharp to blurry at 25 feet? This sounds like something else might be going on.
Probably a combination of using a small aperture and focusing errors. It is easier to manually focus on objects up close than on people sitting at 25 feet - you're just not going to be able to see the details of their features in the viewfinder to confirm focus. And if he's using a K-x/K-r camera, the pentamirror doesn't help either.
@mishmatta:
Can you describe in a bit more detail your Sears lens? Is it made in Japan or Korea? Metal or plastic? A photo would help. I have a metal one made by Ricoh and it's a decent lens - if you have the same, it is probably the best lens in your lineup.
Cheap zooms under $100 won't give you greater IQ than your kit lens or a Sears-Ricoh lens. Frankly, no cheap lens under $100 will beat your kit lens in 18-30mm range. You could go for a Helios 58/2 - that lens is sharp wide open and can be found under $100. Otherwise, just practice more with your Sears or with your kit lens.
And do post some sample shots so we can see what exactly is the sharpness issue that you are hitting. My feeling is that you are not using your lenses to their full potential and buying more inexpensive stuff won't get you anywhere.