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08-01-2010, 08:55 AM   #1
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Newbie K7 18-55mm poor focus

I am concerned about the focus on my brand new K-7. it came supplied with two kit lens - 18-55mm and 55mm-200mm. Neither of them seem to have pin sharp focus. I have been testing the 18-55mm by photographing a wall with a window frame, so there should be reasonable contrast for the AF to latch onto. The autofocus is softer than the manual focus, but I cant get sharp focus manually either.

I have attached a couple of pictures for anyone to comment on, to see if I am expecting too much. They are from the 100% RAW file, opened and cropped in Irfanview. Both were shot at 24mm f56, ISO100, no sharpening or anything else, as far as I know.

Any thoughts?
Graham

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08-01-2010, 09:17 AM   #2
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PS -both shot on a tripod as well.
08-01-2010, 09:23 AM   #3
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Did you turn off Shake Reduction?
08-01-2010, 09:24 AM   #4
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did you turn off shake reduction? it needs to be off when you use a tripod. Are these 100% crops?




EDIT: IRA!!!!

08-01-2010, 09:26 AM   #5
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QuoteOriginally posted by mtroute Quote
did you turn off shake reduction? it needs to be off when you use a tripod. Are these 100% crops?




EDIT: IRA!!!!
I BEAT YOU!!!

Also, if you use your self-timer, shake reduction is automatically disabled.
08-01-2010, 09:40 AM   #6
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Shake reduction is off. these are photos opened in Irfanview at 100% and then cropped to the size you see. I was 36 inches from the wall.
08-01-2010, 09:55 AM   #7
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Well, I'm no great judge on this, but for 100% crop, I don't think it's that awful.
08-01-2010, 10:06 AM   #8
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but not good?

08-01-2010, 10:45 AM   #9
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Try using the Pentax supplied software. If it doesn't crash, it's probably considerably better at the conversion than Irfanview. Even still, you might be expecting a bit much out of the kit 18-55. It's a decent lens for what it is but if you're looking for tack sharp pixel peep 100% crops, start saving for a better lens.

08-01-2010, 11:46 AM   #10
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QuoteOriginally posted by grayboy Quote
but not good?
For 100% crops, they're pretty on par for what you can expect.
08-01-2010, 12:41 PM   #11
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Ok - bear with me, I am just tryng to figure out what the baseline is here. I have an upload from a photo shot last year on a Nikon D60. I cant do a direct comparison re the focal length, or sharpening or anything, and it was very sunny (should this matter though) so maybe this is irelevant, but it seems odd that for a camera that was released a year earlier, for less than half price of the K7, and with only 10megapixels, that to my, very untrained, eye the focus looks so much crisper and cleaner. I am pretty sure the lens used on the Nikon would not have been anything other than a kit lens either. Everything wa shot in auto as well. Am I being unreasonable here? I dont want to get into any Nikon vs Pentax arguement. I bought into Pentax, and I'll live with it, I just want to make sure I am getting the best out of the camera. I feel a bit disappointed that having dropped 1000.00 on the camera and lens that I am being told bascially the lens are pretty much useless. So I suppose what I am asking os for reassurance that if I manage to get a 'decent' lens kit the K-7 will give me pictures at least as crisp as the D60 - which like say on paper appears to be very much inferior.

EXIF info for the Nikon D60 shot

ImageWidth - 160
ImageLength - 120
BitsPerSample - 8 8 8
Compression - 1 (None)
PhotometricInterpretation - 2
Make - NIKON CORPORATION
Model - NIKON D60
StripOffset - 123228
Orientation - Top left
SamplesPerPixel - 3
RowsPerStrip - 120
StripByteCount - 57600
XResolution - 300
YResolution - 300
PlanarConfiguration - 1
ResolutionUnit - Inch
Software - Ver.1.00
DateTime - 2010:02:13 19:30:02
ReferenceBlackWhite - 0
ExifOffset - 468
DateTimeOriginal - 2010:02:13 19:30:02
ExposureTime - 1/500 seconds
FNumber - 5.60
ExposureProgram - Not defined
ISOSpeedRatings - 125
DateTimeOriginal - 2010:02:13 19:30:02
DateTimeDigitized - 2010:02:13 19:30:02
ExposureBiasValue - 0.00
MaxApertureValue - F 4.00
MeteringMode - Multi-segment
LightSource - Auto
Flash - Flash not fired, compulsory flash mode
FocalLength - 90.00 mm
UserComment -
SubsecTime - 00
SubsecTimeOriginal - 00
SubsecTimeDigitized - 00
SensingMethod - One-chip color area sensor
FileSource - Other
SceneType - Other
CustomRendered - Normal process
ExposureMode - Auto
White Balance - Auto
DigitalZoomRatio - 1 x
FocalLengthIn35mmFilm - 135 mm
SceneCaptureType - Standard
GainControl - None
Contrast - Normal
Saturation - Normal
Sharpness - Normal
SubjectDistanceRange - Unknown

Maker Note (Vendor): -
Data version - 0210 (808595760)
ISO Setting - 125
Color Mode - COLOR
Image Quality - RAW
White Balance - AUTO
Image Sharpening - AUTO
Focus Mode - AF-A
Flash Setting -
Flash Mode -
White Balance Adjustment - 0
White Balance RB - 794
Exposure Adjustment - 68608
Thumbnail IFD offset - 12702
Flash Compensation - 67072
ISO 2 - 125
Tone Compensation - AUTO
Lens type - AF-D G
Lens - 886
Flash Used - Not fired
AF Focus Position - 33816592
Bracketing - 0
Contrast Curve - I #(,15:>CGLPUY^bgkpty~ !%*/48=BGKPUZ^chmqv{
Color Mode - MODE3a
Light Type - NATURAL
Hue Adjustment - 0
Noise Reduction - OFF
Total pictures - 7922
Optimization -
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08-01-2010, 12:41 PM   #12
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I'm not an expert, but I don't see a problem here. You're 1/2 stop or so down from wide open, and these both look like good results. I've never not sharpened. Not for my K100 or K200 or scans from an LS5000 or pictures from various p/s cameras. In a sense it won't make the image sharper, but it will make it look sharper.

I have only the 6 and 10mp cameras, but I know that there's a big difference in how sharp 100% looks between them. It looks sharper on the 6mp camera. With 10mp I can see lens differences that show up less dramatically on 6mp. I'm sure 14mp is another jump. I'm just guessing at the number but with 6mp it's maybe like holding an 11x16" print at reading distance, and with 14mp it's probably more like holding a 24x36" print at that same distance.

I've had problems with lenses that I could see pretty easily at 6mp and easier at 10mp. There was just very flagrant blurring in parts of the image. I could see it even a 50% at 6mp. This isn't blurring at all, it's just maybe "limited sharpness." Maybe you'd do better with another lens, but there are probably lots of lenses that would do worse.

What would help is if you would position your 50-200mm so as to have about the same image size for your window as you did for these pictures, and post similar crops of them to compare. If you have or can borrow another lens you could try that too, although most of us don't have anyone to borrow a lens from (a disadvantage to having a Pentax, sadly.) A lot of people here on the forum will swear that you'll get sharper results from almost any old fixed length lens you can find on ebay, so maybe you can try a $50 experiment and let us know what you find. I had a bunch of fixed length Takumars, don't have them any longer, and don't miss them, except for their mechanical feel, which was totally superior to that of any of my "consumer" DA or F lenses. Maybe I'd be pickier with 14mp, but even then I'd want a better zoom, not a fixed-length lens.

Incidentally thanks for posting crops. Lot of people post full frames at 900x600 or something and ask if they're sharp.

Paul

Edit: wrt your most recent post, unless I missed something, you're comparing 100% from 10mp and 14mp, and you just can't do that. It'll be the same difference I see between my K100 and K200, where the K100 100% crops often appear sharper.
08-01-2010, 01:15 PM   #13
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Is that Nikon's Kit lens? Maybe my eyes are a little screwed up but that one doesn't look razor sharp either. If you want to show us a compare, compare the same subject, same focal length, etc.

08-01-2010, 01:27 PM   #14
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QuoteQuote:
I'm just guessing at the number but with 6mp it's maybe like holding an 11x16" print at reading distance, and with 14mp it's probably more like holding a 24x36" print at that same distance.
Hm - so are you saying that if I view a a 14 megapixel image at 66% that would be a more accurate comparison when viewing a 100% of 10megapixle image. Ok that sort of makes sense.
08-01-2010, 06:15 PM   #15
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QuoteOriginally posted by grayboy Quote
Hm - so are you saying that if I view a a 14 megapixel image at 66% that would be a more accurate comparison when viewing a 100% of 10megapixle image. Ok that sort of makes sense.
Yes, something like that would be a more reasonable comparison, because the objects in the photos (assuming you had images made under the same conditions) would be about the same size.

It's still very difficult to compare photos of completely different subjects taken under different circumstances.

Paul
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