that'll do!

I have been trying out the bargain 100-300 Sigma (Quantaray label), the small f/4.5-6.7 model. Other than contrast, and a small drop in sharpness, this lens is more than suitable for what I will be asking of it. Below is a shot at 300mm, the original plus Picasa-fied version (boosted shadows/fill/highlights to taste, and sharpened a touch), then collaged & cropped.

 

Plenty good enough for what I do. BTW this is hand-held through a windowpane of unclean glass, shot wide open (f/6.7) spot-metered @ iso1000. Now that's a torture test! :^)

comparing 50-200WR and Quantaray (Sigma) 100-300 at 200mm

I actually won a telephoto bid! A Quantaray open-box deal came to me for a good price, which keeps me from spending $200+ on a long tele that won't get much use - that's a good thing!

First tests with the lens show it to be decently sharp, easily "sharp enough". Its shortcoming seems to be contrast, which makes an image look softer to me than it is. This doesn't look like a problem to me, and with the k-x abilities at higher ISO the slow specs on this lens (f/4.5 at 100-155mm, f/5.6 to 230mm then f/6.7) are less damaging: just set at f/8 and let ISO compensate.

comparing kit-wr lens and Sigma 17-70

Although the 17-70 is a stronger offering in every way - build, speed, and range - the light weight of the Pentax 18-55 makes it a fine knockaround option. Its weather resistance is a good thing too, even on a less-sealed body like the k-x... but is its image quality too great a compromise?

 

It appears not - these two shots were taken consecutively at iso320 and Av mode set wide open. The DA18-55 is on the left here, and while a decent bit slower at f/5.6 (48mm, where the Sigma is at f/4) its image quality on this scene is more than adequate. Sharpness looks as good, bokeh a bit better. The Sigma image is set at -2/3EV to match up the exposures, so the DA lens picked a better setting. At around half the weight, and given the k-x talent at higher ISO settings, the result is quite impressive for a lens about 1/3 the cost (actual costs: $95 new vs. $250 used!).

Nice to know my camera has a good all-purpose lens for easy snaps. I still expect the 17-70 to be the choice when image quality is most important though - but both are quite versatile!