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08-08-2012, 10:06 AM   #1
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18-55 not a great lens???

Ok dumb question here...

The 18-55 kit lens that comes with the Pentax K5 isn't the greatest lens, is it???

08-08-2012, 10:07 AM   #2
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It isn't.

It's pretty good though. Better than the Canon/Nikon versions.
08-08-2012, 10:09 AM   #3
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I just got my K5 yesterday. I got some decent pics so far. The lens doesn't seem all that sharp though.
08-08-2012, 10:12 AM   #4
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no its the greatest kit lens there is

08-08-2012, 10:15 AM   #5
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The 18-55 is not the best lens that Pentax has produced but it is very good for a kit zoom. My copy is quite sharp on my K7 when stopped down to f5.6, a little better at f8. This to me is the best range for the 18-55. Try your zoom at 35mm and f8. If it is not sharp to you then it may be front or back focusing and needs a little adjustment.
08-08-2012, 10:18 AM   #6
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QuoteOriginally posted by ChuckB28 Quote
I just got my K5 yesterday. I got some decent pics so far. The lens doesn't seem all that sharp though.
Example shots with exposure information will go a long way in figuring out whether or not you are overly critical.
08-08-2012, 10:31 AM   #7
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I think it's a fine lens for a kit lens. It is very sharp around 35mm and pretty sharp stopped down from maybe 24-45. It's not the contrasty-est lens there is, but that can be fixed in post processing. Nothing wrong with it and I have taken some of my favorite landscapes with the 18-55. Unfortunately, I may be parting with it soon as I need to try to sell my K-r and the kit lens would likely go with it.
08-08-2012, 10:35 AM   #8
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QuoteOriginally posted by Pioneer Quote
The 18-55 is not the best lens that Pentax has produced but it is very good for a kit zoom. My copy is quite sharp on my K7 when stopped down to f5.6, a little better at f8. This to me is the best range for the 18-55. Try your zoom at 35mm and f8. If it is not sharp to you then it may be front or back focusing and needs a little adjustment.

Ah... That might have been my problem. I was shooting at f3.5 for many of the pictures.

08-08-2012, 10:40 AM   #9
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Perhaps this is an overly broad generalization, but I'd say that the DA 18-55 seems to be better than many of Pentax' older kit zooms as well. Better IQ, better close focusing, and it comes with a hood, compared to the couple of old kit zooms I've accumulated.
08-08-2012, 10:43 AM   #10
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Its a kit lens, but its a very good kit lens.
08-08-2012, 11:34 AM   #11
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QuoteOriginally posted by ChuckB28 Quote
Ah... That might have been my problem. I was shooting at f3.5 for many of the pictures.
Lenses get better stopped down compared to wide open. Oversimplified, as the aperture closes, stray light rays are reduced and/or straightened out. You get sharper photos with better contrast at smaller apertures. Then lenses get worse as the aperture gets really small. Generally, wide open is the worst, f8 is pretty good, f22 is not good (and you never have that much light anyway).

Zoom lenses are compromise designs so they are not perfect everywhere. Usually at least one end of the zoom is not that great. You can get a slightly better photo with the kit lens at 21mm than 18mm, assuming everything fits into the frame.

Lenses are better in the center of the frame than at the corners. Often the corners are darker (vignetting), or just not as sharp. The better lenses and lenses designed for 35mm are better in the corners. Lenses can also focus in a curved or flat field. Macro lenses are designed to focus in a really flat field, and having very few other defects mentioned here. The Pentax 50mm 1.4 lenses have a more curved field of focus.

Here are some test images that'll show what I'm talking about. I tested my kit lens with four other lenses at 24mm, shooting a newspaper taped to a wall about 8 feet away. Then I crop just the center out of each image and show them side by side. The kit lens is wide open in the first series, and so is the DA 16-45mm f4 zoom. The lenses at either end are really good prime lenses, which have a big advantage here- they are stopped down one or two stops from wide open. (The one in the center is not that good.) The second series shows the difference at f8.



08-08-2012, 11:35 AM   #12
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QuoteOriginally posted by ChuckB28 Quote
Ah... That might have been my problem. I was shooting at f3.5 for many of the pictures.
There aren't any lenses that I am aware of that are at their best at their lowest f setting. Most sharpen up a good bit a stop or more away from that setting (some even more, and some never). The 18-55 is a descent zoom, it's not the best but its better than what I've seen on the Nikon and Canon's I've handled.
08-08-2012, 11:37 AM   #13
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QuoteOriginally posted by ChuckB28 Quote
I just got my K5 yesterday. I got some decent pics so far. The lens doesn't seem all that sharp though.
Could be you also need to spend a little time setting up the camera, checking AF fine adjustment, etc, to 'release' the full potential of the kit lens.
08-08-2012, 11:49 AM   #14
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https://www.box.com/s/b22e5f8ee40b57fa24d2

Camera jpg
at 18 mm and f/16 iso 200 and 1/180th
08-08-2012, 01:16 PM   #15
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yeah, that's where TAv is your friend. (Or P mode, I suppose). Keep that aperture in a good range and you'll be better off.
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