Before I begin this little rant I just want to note that my comments are not directed at Marc per se, but rather at the general consensus among many that a super/utility zoom can not possibly take great pictures.
Originally posted by Marc Sabatella True. Although as I mentioned elsewhere, you should also consider that the 18-250 will force you to miss shots as well because it does not have a wide enough maximum aperture, because its AF is relatively slow, because the focus ring is not as precise as that of a higher quality lens, because of the lack of quick shift, or even perhaps because you are that much less likely to have the camera with you than you might with a significantly smaller lens.
Actually, AF on the DA18-250 is just as good as the DA*50-135 in mediocre light; at least in so far as you would notice in practical use.
I just did a test to be "double plus good sure" with the two lenses and my K20D. The exposure for the shot was 1/15s f/5.6 ISO200 @ 135mm and a range of ~25ft from my office desk to the window in the nursery. Both lenses achieved focus at just shy of 2sec from minimum focus setting. The 18-250 actually spun up faster than the 50-135 but had micro adjustments at the end which took about 200ms by my estimation. So if the camera had locked on the initial spin up from "zero" the 18-250 at 135mm would actually have been FASTER at its f/5.6 max aperture than the 50-135 at its f/2.8. Go figger.
Here's the shot from the 18-250 (resized for web only):
[imgwideleft]http://www.perzactly.com/posts/jdg03712.jpg[/imgwideleft]
The shadow on the left is a bookshelf in my office, the shadow on the right is the office door.
The whole missing shots due to low light performance really isn't valid in my opinion. The time it takes you to switch out lenses to go from one prime to another, or short to long zoom, will cause more "lost shots" than
any lens' individual AF performance. But with that in mind - the Penron 18-250/3.5-6.3
is not intended to be used as a low-light without flash lens. It is an
f/8 and Be There daylight utility zoom, and if you use it for that purpose there is no other lens on the market for Pentax or any other brand now or at any time in the past that can beat it. But anyone trying to use it for anything else has wasted their time and money.
Originally posted by Marc Sabatella Plus you have to accept that many of your shots will be compromised a bit in IQ over what is possible with higher quality lenses. As it happens, all of these issues are most pronounced indoors in low light.
Sure they will, just like the IQ is lower from the DA18-55/3.5-5.6 kit compared against the DA*16-50/2.8 or one of the limited primes. You shouldn't use a sledge hammer to cut diamonds either.
Please understand that I am not preaching the DA18-250 as the messiah of lenses. It just happens to be one hellofa good piece of optical engineering that deserves a bit more recognition for what it is and what it really can do.
Here are a couple shots I am particularly proud of from this little lens:
[imgwideleft]http://www.jimgillispie.com/photos/371319685_vMbTF-XL.jpg[/imgwideleft]
[imgwideleft]http://www.jimgillispie.com/photos/399261673_aguGc-XL.jpg[/imgwideleft]