Originally posted by jwquinn68 I have a K-70 that I really like and am still learning about. I like to do macro photography and I have a Sigma 16-80 mm Macro lens that does a pretty good job. I paid $16.00 for brand new! I happened upon a good deal when Kit's Cameras was going out of business. The only drawback is that has a tendency to be soft. Even focusing manually, I can't get seem to get it as sharp as I'd like. I'm looking for recommendations on a replacement, preferably a Pentax lens. I looked at the 50 and 100mm macros but they are FF. I'm not sure how well they'd perform in APS C.
I took some pics with my Sigma last weekend, and this seems to be the best of the bunch. The blossom is about the size of my thumbnail & the grasshopper might be a half inch long. Thanks
I can't see any Sigma 16-80mm macro in the database. If it's an old (film era) lens it's more likely to be 24-80, 28-80 or 35-80 - 16mm was extremely wide on a 35mm film camera.
Anyway Sigma is notorious for bandying the "Macro" appellation, commonly applying it to lenses that only give 0.3x magnification. Those sort of zooms can be handy for close focus, but they really are no match for a true 1:1 macro lens.
Incidentally, the EXIF for your photo says that it was with the Pentax DA 18-135. It's pretty good for close focus but still only 0.24x magnification.
I have the FA 50mm f2.8 macro and the DFA 100mm f2.8 macro WR. As others have said, each works very well on APS-C. The narrower FOV at a given focal length with APS-C is often an advantage for macro. Both lenses are exceptionally sharp. I use the 100mm a lot more than the 50mm for macro because of the extra working distance. With the 50mm you need to get to 19cm from the subject for 1:1 magnification, whereas for the 100mm it is 30cm. (For the DA 35mm f2.8 macro Limited it is 14cm.) For static subjects (e.g. coins or stamps) the difference wouldn't matter so much (although if the lens is very close to the subject lighting could be more awkward), but for anything that moves (or bites!) the extra distance is an advantage.
There are numerous options in focal lengths between 90mm and 105mm, from the Tamron 90 to the Sigma 105 and many different 100mm lenses. That's where I'd suggest you start. For macro, manual focus will be fine because you often have to focus manually anyway and MF lenses may be cheaper.
For general (non-macro) use, many people will find a wider lens (like the 35mm Limited macro) more versatile, although personally i have warmed to 100mm as a general focal length on APS-C.
I do love the DFA 100.