I have a Pentax K100D and a SMC DA 18-55mm lens (the one that came with the camera). I want to get a good zoom lens but there are so many that I am not sure what to get. I have considered the SMC P-DA 50-200mm F4-5.6 ED, the SMC P-FA J 75-300mm F4.5-5.8 AL, and other older pentax lenses like these. Are Sigma and Tamron lenses worth considering? What lens do you think I should get? Its hard to tell without knowing something about how you want to extend your photography.
These longer focal length zooms can be very specialized and really need other accessories like a good tripod to get the best out of them.
I shoot film with a variety of Nikon bodies, and one of my favourite all round zooms is the Tamron 28-200mm. I also have an older Sigma 70-200mm manual focus, but I prefer the Tamron for most circumstances even though it is much bulkier.
I would read the reviews to get a feel for these lenses and whether they are going to meet your specific needs. | 