Originally posted by Marc Sabatella It comes Monday (although I might be out and miss it; not sure if I can or should get UPS to leave it anyhow, so it might be another day or two). Anyhow, sure, I'll do that, but aren't there full size samples all over the net you could use to do it yourself?
I know from experience with cropping in other contexts that, assuming the lens is not a complete dog, I'm personally almost always satisfied with results of cropping down to 1/2 the original dimensions (1/4 the original area) on my 10MP K200D. That reduces my image from 2592x3872 to 1296x1936, and virtually everything I do with my images is done with 1200x1800 JPEG's I generate from the original RAW files - it's the 1200x1800 JPEG I upload to Zenfolio/Flickr/etc, it's the 1200x1800 JPEG I send to family and friends when necessary. And when it comes to prints, a 1200x1800 JPEG is enough resolution for 300dpi at 4x6" (which is why I chose those dimensions for my JPEG's).
It's the very rare image that I need more resolution than this for - to print larger, or because I have a "client" who needs more resolution for their own prints. And pretty much every lens I have can withstand cropping down to 1/2 dimensions and still have acceptable quality to me - only my el-cheapo Samyang-made Vivitar 500/8 mirror gives me pause (but I'll still go there!). But aside that one one lens, I have to say that at full screen view or in 4x6" prints, I can barely tell the difference in sharpness between an image cropped to 1/2 the dimensions versus one shot with a longer lens. Given that the DA15 got about the best scores for center sharpness of any lens not named FA43 Limited, I have to believe it will work out at least as well for cropping as my other lenses.
This suggests that my DA15 could actually cover the entire range from 15-28 for me "most" of the time. Obviously not at the level of quality where I'll actually be likely to use the DA15 in place of my M28/2.8 in general, but I'm confident it will do everything I need in order to consider it a "15-21 digital zoom". Back of the envelope calculation here - seems like if cropping the image down to 1/2 dimensions yields an image with just enough pixels for my 1200x1800 JPEG's, and that's the equivalent of a 30mm lens (yes?), then to simulate a 21mm lens, I could keep at over 1600x2400 pixels, and that would be good for an 8x12" print at 200dpi. I'd still be generating those 1200x1800 JPEGs and using those for most purposes, but if I wanted to print 8x12", I don't think I'd be afraid to do so. If I expect to be hanging in art galleries, I might yet spring for the DA21 - but really, I'm not unhappy with the performance of my DA18-55II at that focal length, either.
I believe that is the idea Marc. somehow I would think if the DA15 was more of a better or logical choice compared to the wider zoom, be it the 10-20,12-24, 16 and onward zooms, as far as acceptable print size versus dpi are concerned. for someone who doesn't need more than 1600x2400 pixels large prints, I think the lens would suffice at equivalent focal length of 24. I would think that you won't need to push it at 28, let alone 30mm. the center sharpness alone of the DA15 is already worth of anyone's attention.
though a new Pentax camera with a higher resolution of 24MP or better yet 30MP would boost your cropping chances of pushing it further beyond a few more lengths and produce acceptable quality results.
somehow I think if the additional 3mm wideness of my 12-24 lens and strong and consistent performance on all aperture openings is worth it? I somehow no longer question nor need to think if I still need the 18mm and 24mm zoom range of the lens because of the quality of the cropped image (distortion is being considered here, as well as the resolution of the zoom lens at 18mm and 24mm). though there is a quality resolution variation at f4 on those focal lengths.
I do love the 12-24. but DA15's less than half the size and weight of the 12-24, makes the DA15 more travel and baggage friendly. I had to do some indoor and close quarter shots just to validate my purchase of the 12-24, and the 3mm difference does quite add up and see it's usefulness in very tight situations. I have the 18-55 WR to cover my 28mm to 35mm range and for the seasonal rainy day shoots. I do like the 18-55 center sharpness, but the weak border resolution and low contrast at the wider end (18-24) is keeping me from giving it a very good score, though at 28-35mm, I got some really consistent and nice results. this is also the reason why I got the 12-24, to fill the wide gap for landscapes and close corner shots.