Originally posted by I robert I have a tamron LD-DI 70-300 MAC & SIGMA DL mac super i'm not over impressed with either , not that sharp & seem soft is the pentax 55-300 better ?
or other option plaese:
Probably not what you are looking for but the Tamron SP 60-300mm (23A) is worth considering if you are willing to carry and use a heavy manual lens.
I think it matches the Pentax 55-300mm I have regarding IQ and in "macro" as well as through the range it exceeds the IQ my AF Tamron and Sigma.
It has been reported as NOT a genuine 300mm lens at the long end, more like 285mm, but I cannot comment on this.
Having an Adaptall mount with an "A" setting makes it a lot easier to use than manual or green button metering but finding one that doesn't cost less than the lens is not easy, they seem to command good prices.
It is rather a good lens and is better than the other to 300mm legacy manual lenses I have tried.