Originally posted by bigted Every time I am on the verge of buying a longer lens something crops up and dashes those plans. Once again I am on the edge of buying a digital long lens. Currently I have a K-3 and the HD PENTAX-DA 55-300MM F4-5.8 ED WR and a older film era AF 400mm Sigma that I picked up used for a song a few years ago. It has a tendency to hunt for the focus and isn't very quiet. None of the local Pentax suppliers actually has the lens in stock and for me to get one I need to pay for it before I even get to touch it. There are a lot of lovely shots in this thread and I am wondering if I am going to be happier with the DA* 300mm f/4 ED (IF) (and eventually the 1.4 TC)?
Although the EXIF doesn't show up on this shot it was taken with the Sigma 400mm f5.6:
Certainly the DA*300/4 + 1.4x TC will be a step up in IQ from the old Sigma 400. Sharper, less CA & PF, more contrast, livelier color, quieter AF, WR. Will you be happier after spending the $1500? Hard to say. $1500 is a lot of money. I have multiple long teles that have a total value of $1500, but the thought of spending that much on one lens + TC makes me wince.
It really stinks not being able to try before you buy. I think most of us are in that boat.
My own, personal solution to the Cost Conundrum was to buy older, quality manual-focus glass. Still not as good optically as modern wonders like the aforementioned DA*300/4 and the DFA 150-450, but good sharpness nevertheless and I enjoy the different flavors of my older lenses.
Anyway, have you considered buying a used DA*300/4? Not only would you save money initially, but if you were to decide that the lens is not for you, you could re-sell it at a minimal loss.