Pentax DA 12-24mm f/4 ED AL (IF) ...- User Rating: 
Summary for Pentax DA 12-24mm f/4 ED AL (IF) ...- A nice ultrawide
Notes on Pentax DA 12-24mm f/4 ED AL (IF) ...- This lens covers a handy range of focal lengths. At 24mm (equivalent to 35mm on a 35mm film camera) it replicates the popular moderate wide angle that is handy for car shows, architecture, landscapes and group shots.
Go down to 12mm, and you get a very wide view, great depth of field, and essentially no barrel distortion.
Although there is some overlap in the focal length of the Pentax 10-17mm lens, that one has the pronounced "fisheye" distortion (though not too much at 17mm), while the 12-24 maintains straight lines (it's "rectilinear") though if you are tilted up (or down), your subject will lean in (or out).
More expensive than some lenses but less than others, I say it is worth it. Its constant f4 maximum aperture is part of the cost (and weight).
It is a little bulky, not lightweight, and has a rather large lens hood, so you might have to rearrange your bag divider...
Pentax DA 12-24mm f/4 ED AL (IF) ...- User Rating: Summary for Pentax DA 12-24mm f/4 ED AL (IF) ...- Do you hesitate to buy it?
Notes on Pentax DA 12-24mm f/4 ED AL (IF) ...- This lens is savvier, more perfect than I expected. I don't need to say about pros because lots of people already say about that in review. But this lens' weight is quite heavier compared with other Pentax lens.
Pentax DA 12-24mm f/4 ED AL (IF) ...- User Rating: 
Summary for Pentax DA 12-24mm f/4 ED AL (IF) ...- Vivid color, amazing linearity, sharp to corners - but delicate alignment
Notes on Pentax DA 12-24mm f/4 ED AL (IF) ...- Pop Photo (Apr-06) praised this lens as a "Wide Winner" for spectacular performance on bench testing: excellent image sharpness and contrast; imperceptible distortion ["best of breed"]; and barely notable vignetting at the short end. I can add breathtaking color, crisp contrast and ruler-straight linearity to that list. At first glance, a 2X zoom doesn't sound impressive these days - until you realize that this parafocal zoom sweeps an incredible 100 to 60 degree viewing range, that's just perfect for cramped interiors, group pictures or landscapes. This zoom is a landmark of stellar engineering: combining extra-dispersion glass and aspheric lens elements into flagship "great glass".
But a finely-tuned optical engine performs optimally only if all cylinders fire in unison ... at daylight trial, I noted a hideous 'purple fringing' [chromatic aberration] of trees and power lines outlined against an overcast sky -- something was badly remiss. Rather than returning the lens, I packed it up for warranty service so as to alert the manufacturer to quality control slippage. Irreparable misalignment [probably from rough shipping/handling] was acknowledged; replacement with a brand-new lens was hassle-free as well as timely.
Should you detect distortion (run some test shots before starting a formal shoot!), fear not -- Pentax service was knowledgeable, courteous, and helpful. To their great credit, exchange was virtually painless, and the new replacement lens at last performs flawlessly. Although the initial unit turned out to be a glass lemon, Pentax made good (try that with a new car!); I have nothing but praise for the fair and decisive warranty follow-through.
Tip: the bulbous cyclops snout of the forward element is close to the surface, begging for scratches and smudges. Protecting the front end with a haze or UV filter in essence adds an unproven 14th glass element to a balanced optical design -- buy the high quality multi-coated filter (mounted in a thin WA ring) this star performer deserves to minimize glare, internal reflection and corner vignetting.
Pentax DA 12-24mm f/4 ED AL (IF) ...- User Rating: Summary for Pentax DA 12-24mm f/4 ED AL (IF) ...- A must for the wide end
Notes on Pentax DA 12-24mm f/4 ED AL (IF) ...- The main problem with the APS-C sensor is the fact that to get a very wide angle of view, you need a special lens. My old 20mm lens, which has served me for many, many, years, is just a moderate wide on the digital sensors.
With a few doubts, I sprang for this super-wide zoom.
WHAT A SURPRISE! This lens is AMAZING!
Low or no distortion (you can get away without correcting for distortion in Photoshop - quite a feat - unless you have a fanatical lunatic architectural client). CA hard to see. Very sharp, sharper wide open than any zoom has a right to be!!
Flare is so well controlled, I shot right into th sun and did NOT get the usual string of circles, just one ghost. How do they DO that???
The constant aperture is a blessing (I still refuse to buy a zoom with a variable aperture).
All modern lenses are polycarbonate. Supposedly, it's more dimensionally stable than metal under temperature extremes. Maybe so, but I still have some of the older K and M lenses and some Limited lenses. I guess I'm just old fashioned.
But with the APS-C sensor, you need a VERY wide lens. This is the one that will save your hide on any assignment where you need ultra-wide angle of view.
Penatx has always been known for their glass. With this lens, they continue to impress those who know that the glass is what counts!
