[zosxavius]

From all the comparisons I've seen the only lens that comes close to the pentax is the tamron adaptall 60-300, but it gets pretty soft over 200mm, where the pentax holds an edge. That tammy at the wide end is super sharp and its macro mode is a ton of fun with catch in focus. At $60 its totally worth keeping in your arsenal. I want the. Pentax next and am bummed out prices just went up. Really wish they had a wr version. For nature shots zooms in this range are extremely versatile. Especially with a macro mode. With catch in focus as a poor mans af, I've gotten some pretty decent bird shots with the tammy and from what I've seen the pentax would be spectacular...I really want one. Its certainly worth the money.

[luftfluss]

Ha-ha..........to clarify, I'm trying to trade an 18-200 Tammy in this post here: https://www.pentaxforums.com/forums/photographic-equipment-sale/184990-trade-...-55-300-a.html

So anyways, Fluss is correct in that the Sigma I've found is an older non-HSM APO before they did away with the aperture ring

For under $100, I'd be all over that Sigma.

I second that wholeheartedly! I picked up the Tammy so cheap (brandnew) I didn't even notice the money was gone

I barely ever need anything longer than my DA*50-135mm but on the rare occasions I do, it's a lifesaver. The purple stuff is dealt with quite easily by using the Lensfun library in raw conversion and a dedicated purple-defringifier plugin in GIMP.

Now, close-up is a whole different cookie! I do have the Sigma 50mm/f2.8 EX DG Macro and it is absolutely fabulous but forces you to almost physically crawl into whatever you're shooting. The Tammy does well on its 1:2 macro mode and because it's so lightweight, it gets thrown into the bag when I travel. I find the bokeh when in macro mode quite pleasing actually.

The convenience & results of the Tammy are so good, that I also ditched my Vivitar 100/3.5 macro, which was sharper, but less convenient. I also noticed that the Raynox DCR-150 close-up adapter works better with the Tammy than the Pentax 55-300, which would vignette at certain FL's. I think the Tamron's larger diameter helps in this circumstance.

Even though it's only 1:3 at 300mm, I don't think the 55-300 has any problems with close-ups.

The 55-300's maximum magnification is actually 1:3.5, it's just not the same as 1:2. While the Pentax does have some advantages over the Tamron - 55mm, far less PF, better color & contrast - the Tammy is at least as sharp (if not sharper) and for my applications, the minimum focus distance being 2/3 that of the Pentax is a huge asset. I'm fortunate enough, though, that if I need to do real long shooting I have the Sigma 170-500.

[johnha]

I haven't used the 55-300 but have an old Sigma 70-300 APO (non-HSM - can't remember when I bought it but it was for Pentax/Samsung) and the Tamron Adaptall-II 60-300. I haven't really compared them but gut feel suggests the Tamron is better optically, but the Sigma is easier to use on an AF body. Both of these are full frame with aperture rings, important for me as I have several film bodies.

[zosxavius]

The tamron 23a is easily one of the sharpest zooms ever. It is a real beast. There is some ca, but stopping down makes it almost negliable. It is almost as sharp as some of my primes @ 60mm stopped down. I imagine the pentax 55-300 has better across the range performance as well as being a lot lighter. From what I've seen, the contrast and color rendition is far superior as well. Shots out of the tmmy have a very vintage look imo. I kind of like it, but would prefer the 55-300 for nature and flower shots. I'm ok with carrying a dedicated macro and have been thinking about the vivitar series 1 an awful lot. Really, you can't have too many lenses and anything under. $100 is a decent buy. Worst case you could always resell when you move up to something better.