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01-05-2012, 08:52 AM   #1
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Need help to confirm that my new K-5 and kit lens is not a bad copy

Hi,

Just brought the K-5 with 18-55mm kit.

After some initial testing, I find that most photo from it are quite soft.

So did some tripod, 2 sec timer shots to confirm, seen some improvement but things are still not sharp.

Have then read that the kit lens is not that great at 55mm, but from some of the sample images I have seen, there are better than mine shots.

So, I would just like to do a few standard test to check things out, so if you are in my situation, what kind of shots will you do to check things out quickly?

If I can prove a problem, I might be able to get the shop to exchange for another copy before it is too late.

Any help welcome.

-kk

01-05-2012, 08:55 AM   #2
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If you want, you can check the lens for focusing problems using the steps indicated here:
Fixing Front and Back Focus - Introduction - PentaxForums.com

To check for stains, take a picture of the sky at F16 and see if something that looks like a string of pearls is visible on the photo.

Apart from that, I would experiment with various shutter speeds and F stops. If you just can't get a sharp image, chances are that the lens is busted (though it would be nice if you had another lens to show that).

Adam
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01-05-2012, 08:56 AM   #3
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might it be the camera slightly front/back focus?
f/b focus is usually the case for soft images.

i would recommend shooting a focus chart in different focal length and check out the result.
01-05-2012, 09:10 AM   #4
kkx
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Will have to go through the focus checking step by step a bit later this week.

I am doing some casual snap shot to see if I can feel confident that things are normal.

Did the stain check already, and it seem ok/clean.

-kk

01-05-2012, 09:13 AM   #5
kkx
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QuoteOriginally posted by telly0050 Quote
might it be the camera slightly front/back focus?
f/b focus is usually the case for soft images.

i would recommend shooting a focus chart in different focal length and check out the result.
I am worry about f/b focus and the kit lens being a dud.

at 18mm:

AF (phase detect):
IMGP1169 | Flickr - Photo Sharing!
MF LV by my eye (as best I can):
IMGP1170 | Flickr - Photo Sharing!

at 55mm:

AF (phase detect):
IMGP1173 | Flickr - Photo Sharing!
MF LV by my eye (as best I can):
IMGP1174 | Flickr - Photo Sharing!


With out access to the original image, can you tell if things are normal?
01-05-2012, 10:41 AM   #6
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Maybe im crazy but they look fine to me, all the text is sharp, what are you expecting? These look pretty decent for a kit lens at f4?

That said it looks like you have shot these straight on, you need to take these test shots at a 45 degree angle to see if you have FF/BF, but based on these I doubt it
01-05-2012, 11:12 AM   #7
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these photos look fine to me, maybe because it wasn't 100% magnify.
18mm looks sharper than 55mm though.

as deimos mention, to check ff/bf, you need to shot in an angle, not straight on.
01-05-2012, 11:20 AM   #8
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you don't need a fancy chart either just line up a row of AA batteries and shoot it at a 45 degree angle picking the center one as your target. review the image on a monitor and make some adjustments

01-05-2012, 02:52 PM   #9
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First thing I always do as a control is to compare manual focus with autofocus.
01-05-2012, 03:55 PM   #10
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Your kit lens seems fine, judging by your sample pix.

This is what a bad copy of a lens looks like (a dud Tamron 17-50), using the same test chart you used:

01-06-2012, 03:49 AM   #11
kkx
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good to know

Thanks everyone who had replied. It is good to know that things are not badly wrong.

From so many QC issue, I was a bit worried when I saw that some of my photo is not sharp (compared to similar photos taken using another DSLR). I think viewing photos at 100% is not helpful.

Thanks again.
01-06-2012, 06:01 AM   #12
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Also be carefull if photo hve been postprocess.
01-07-2012, 02:53 PM   #13
kkx
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all is well it seems

Hi,

After some simple check, seems like all in ok.

-no decentering
-no obvious FF/BF even in low tungsten light

I have limit my "infocus/sharpness" check to x11 view in playback, that helps.

-Kit lens have lower contrast and sharpness compared to canon kit lens, especially at 55mm (at least for my copy of both),

-Pentax jpeg have less tweaking done in camera by default, I have turn up jpeg contrast and sharpness so that it is more comparable to what come out of canon 550 (just for the sake of checking things are ok, in future, will do this in PP).

-SR noise in live view is quite annoying, SR seems less effective than in lens IS at times.

-high ISO noise is very good for K-5

Generally very happy with K-5. All my MF lens are now usable in low light (green button, SR, high ISO, bright and larger OVF etc).

Thanks to members that try to help.

-kk
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