PENTAX K-7 Lens Correction
This video short will introduce the PENTAX K-7′s advanced Lens Correction functions. Correct for distortion and lateral chromatic aberration in your K-7 DSLR camera with every digital lens. You can also make small adjustments to front and back focus for all of your lenses, saving your settings in your K-7. Please note that distortion correction is disabled for the DA 10-17mm Fisheye lens, since the fisheye effect is optically intentional.
The 17-70 is one I’m looking at right now. It’s a toss up between that and the Tamron 17-50 f/2.8. Just need to decide if the constant aperture is more important than the extra range. In the end, I don’t think one can go wrong with either.
On the long end, there is nothing else that will get you out to that range for the money. The closest is the Tamron 70-300, but the amount of purple fringing it may produce far outweighs any extra sharpness it may have, IMO. The only other consumer grade lenses to get you out that far are the Pentax 55-300 and Tamron 18-250/270. Both are great lenses, but you will pay about twice as much for them. The 18-250 was just being released when I got my K10D. I had considered it, but the only information out there on it where from review sites. While they rated it highly, there wasn’t enough out there from actual users, so I passed. If I could do it again, I’d probably go with that instead of the kit 18-55 and the 70-300.
From what I’ve seen from the Pentax 55-300, it’s probably about on par in the bang for buck rating with the Sigma. It gives you more bang, but for a few more bucks.
The other two lenses that can have good performance on Pentax K-7 are:
Sigma 17-70mm f/2.8-4.5 DC IF Macro Lens
Sigma 70-300mm f/4-5.6 DG APO Macro Telephoto Zoom Lens
