18-55 kit vs 18-250 mm

How does the 18-55mm DAL lens compare with the 18-250mm lens in the 18-55 range in terms of AF speed, sharpness and IQ?

On the face of it, in practical terms they both do very well and there's no difference. They both also have no QuickShift.

It may well be that there are differences technically, but I would happily use either.

Dave

I'm not sure about the comparison between the two lenses you mention, but I have one observation about the 18-55 lens. It's a great all-rounder, but it does seem to suffer a little from a lack of edge sharpness. This is quite noticeable when comparing with my DA 16-45. The centre frame performance is about the same on both lenses, but the 16-45 is miles better at the edges and produces a better image overall. That said, I still like the 18-55WR; its a great walkabout lens especially if it's wet outside!

Regards
David

According to photozone, as far as sharpness goes they're similar at the centre but the 18-250 is a little better at the edges.

See the MTF resolution figures:
18-55
18-250

AF speed of the 18-250 will be slower if it is a long way out of focus, however. Manually approximating focus first (to just beyond the required point ideally) negates that deficit.

On these lenses, and others without quickshift, I've found holding the lens release button disengages the drive, allowing manual focus. Not an official operating procedure, obviously. I just find it's quicker and easier than setting/resetting the body's side mounted switch.

I've had both a DAL kit lens and the Pentax 18-250mm and there was little or no difference between them. The DA 18-55mm WR my daughter has isn't quite up to the other two so you have to allow for variations between copies.

And think about 18-135WR as well - pretty impressed so far!

Thanks everyone as ever for your valued opinions. As part of my overall rationalisation I am thinking of replacing the 18-55 with the 18-250. I don't do a lot of walk around stuff but when I do I would still like to cover longer focal lengths even at the expense of quality. I have the long lengths covered well elsewhere for my wildlife photography.
Dave

For what it's worth - after having our 18-250 for a while we sold our 18-55 as it just never got used. Have never regretted that.

By and large, Sue has found that it's not the quality that suffers at longer focal lengths, more the restricted aperture that means slower shutter speeds. Then camera shake can become an issue if the light isn't bright.

So tripod, high ISO and make the best of it when the light is dull. In bright light, no problem.