[PBandJ]

Thanks, this is my first new lens, and quite $$ to me, so pls help me know if I need to exchange. I don't know why the cropped areas aren't identical.

Complete image:



11mm, F4 upper left



11mm, F16 upper left



11mm, F4 upper right





11mmF16 upper right



11mm F4 lower left



11mm F16 lower left



11mm F4 lower right



11mm F16 lower right

[treebeard]

When I look at the EXIF data on Flickr there is no information. We need to know what camera body, what ISO used, etc....in order to help you.

[PBandJ]

When I look at the EXIF data on Flickr there is no information. We need to know what camera body, what ISO used, etc....in order to help you.

I don't know why it got stripped, or how to add it, but this is the data:


Filename - IMGP1162.JPG
Make - PENTAX
Model - PENTAX K-01
Orientation - Top left
XResolution - 300
YResolution - 300
ResolutionUnit - Inch
Software - K-01 Ver 1.02
DateTime - 2013:02:25 11:21:54
Artist - SPC
YCbCrPositioning - Co-Sited
Copyright - ÿ
ExifOffset - 706
ExposureTime - 1/25 seconds
FNumber - 4.00
ExposureProgram - Aperture priority
ISOSpeedRatings - 640
ExifVersion - 0230
DateTimeOriginal - 2013:02:25 11:21:54
DateTimeDigitized - 2013:02:25 11:21:54
ComponentsConfiguration - YCbCr
ExposureBiasValue - 0.00
MeteringMode - Multi-segment
Flash - Flash not fired, compulsory flash mode
FocalLength - 11.00 mm
FlashPixVersion - 0100
ColorSpace - sRGB
ExifImageWidth - 4928
ExifImageHeight - 3264
InteroperabilityOffset - 54468
SensingMethod - One-chip color area sensor
FileSource - Other
SceneType - Other
CustomRendered - Normal process
ExposureMode - Auto
White Balance - Auto
FocalLengthIn35mmFilm - 16 mm
SceneCaptureType - Standard
Contrast - Normal
Saturation - Normal
Sharpness - Normal
SubjectDistanceRange - Macro

GPS information: -
GPSVersionID - 2.3.0.0

Maker Note (Vendor): -

Thumbnail: -
Compression - 6 (JPG)
XResolution - 300
YResolution - 300
ResolutionUnit - Inch
JpegIFOffset - 54610
JpegIFByteCount - 7650
_______________________
Filename - IMGP1169.JPG
Make - PENTAX
Model - PENTAX K-01
Orientation - Top left
XResolution - 300
YResolution - 300
ResolutionUnit - Inch
Software - K-01 Ver 1.02
DateTime - 2013:02:25 11:23:05
Artist - SPC
YCbCrPositioning - Co-Sited
Copyright - ÿ
ExifOffset - 706
ExposureTime - 1/30 seconds
FNumber - 16.00
ExposureProgram - Aperture priority
ISOSpeedRatings - 8000
ExifVersion - 0230
DateTimeOriginal - 2013:02:25 11:23:05
DateTimeDigitized - 2013:02:25 11:23:05
ComponentsConfiguration - YCbCr
ExposureBiasValue - 0.00
MeteringMode - Multi-segment
Flash - Flash not fired, compulsory flash mode
FocalLength - 11.00 mm
FlashPixVersion - 0100
ColorSpace - sRGB
ExifImageWidth - 4928
ExifImageHeight - 3264
InteroperabilityOffset - 54468
SensingMethod - One-chip color area sensor
FileSource - Other
SceneType - Other
CustomRendered - Normal process
ExposureMode - Auto
White Balance - Auto
FocalLengthIn35mmFilm - 16 mm
SceneCaptureType - Standard
Contrast - Normal
Saturation - Normal
Sharpness - Normal
SubjectDistanceRange - Macro

GPS information: -
GPSVersionID - 2.3.0.0

Maker Note (Vendor): -

Thumbnail: -
Compression - 6 (JPG)
XResolution - 300
YResolution - 300
ResolutionUnit - Inch
JpegIFOffset - 54610
JpegIFByteCount - 7697

[treebeard]

11mm F4 lower left and 11mm F4 lower right don't look right. F4 lower right looks fine and less noisy but the F4 lower left shot looks really messed up. Have you tried shooting anything else besides ads? I don't have a K-01 (wish I did though) so hopefully someone else can chime in for some help. Have you tried any other lenses?

[PBandJ]

yeah, I tried bricks too before the ads.

10mm F4 upper left



10 mm F16 upper left



10mm F4 upper right




10mm F16 upper right





10mm F4 lower left



10 mm F16 lower left




10mm F4 lower right




10mm F16 lower right




EXIF F4 IMAGE
Filename - IMGP1143.JPG
Make - PENTAX
Model - PENTAX K-01
Orientation - Top left
XResolution - 300
YResolution - 300
ResolutionUnit - Inch
Software - K-01 Ver 1.02
DateTime - 2013:02:25 10:45:08
Artist - SPC
YCbCrPositioning - Co-Sited
Copyright - ÿ
ExifOffset - 2366
ExposureTime - 1/30 seconds
FNumber - 4.00
ExposureProgram - Aperture priority
ISOSpeedRatings - 100
ExifVersion - 0230
DateTimeOriginal - 2013:02:25 10:45:08
DateTimeDigitized - 2013:02:25 10:45:08
ComponentsConfiguration - YCbCr
ExposureBiasValue - 0.00
MeteringMode - Multi-segment
Flash - Flash not fired, compulsory flash mode
FocalLength - 10.00 mm
FlashPixVersion - 0100
ColorSpace - sRGB
ExifImageWidth - 4928
ExifImageHeight - 3264
InteroperabilityOffset - 58136
SensingMethod - One-chip color area sensor
FileSource - Other
SceneType - Other
CustomRendered - Normal process
ExposureMode - Auto
White Balance - Auto
FocalLengthIn35mmFilm - 15 mm
SceneCaptureType - Standard
Contrast - Normal
Saturation - Normal
Sharpness - Normal
SubjectDistanceRange - Macro

GPS information: -
GPSVersionID - 2.3.0.0

Maker Note (Vendor): -

Thumbnail: -
Compression - 6 (JPG)
XResolution - 300
YResolution - 300
ResolutionUnit - Inch
JpegIFOffset - 58638
JpegIFByteCount - 6792



EXIF F16 IMAGE

Filename - IMGP1150.JPG
Make - PENTAX
Model - PENTAX K-01
Orientation - Top left
XResolution - 300
YResolution - 300
ResolutionUnit - Inch
Software - K-01 Ver 1.02
DateTime - 2013:02:25 10:46:12
Artist - SPC
YCbCrPositioning - Co-Sited
Copyright - ÿ
ExifOffset - 294
ExposureTime - 1/30 seconds
FNumber - 16.00
ExposureProgram - Aperture priority
ISOSpeedRatings - 1250
ExifVersion - 0230
DateTimeOriginal - 2013:02:25 10:46:12
DateTimeDigitized - 2013:02:25 10:46:12
ComponentsConfiguration - YCbCr
ExposureBiasValue - 0.00
MeteringMode - Multi-segment
Flash - Flash not fired, compulsory flash mode
FocalLength - 10.00 mm
FlashPixVersion - 0100
ColorSpace - sRGB
ExifImageWidth - 4928
ExifImageHeight - 3264
InteroperabilityOffset - 53992
SensingMethod - One-chip color area sensor
FileSource - Other
SceneType - Other
CustomRendered - Normal process
ExposureMode - Auto
White Balance - Auto
FocalLengthIn35mmFilm - 15 mm
SceneCaptureType - Standard
Contrast - Normal
Saturation - Normal
Sharpness - Normal
SubjectDistanceRange - Macro

GPS information: -
GPSVersionID - 2.3.0.0

Maker Note (Vendor): -

Thumbnail: -
Compression - 6 (JPG)
XResolution - 300
YResolution - 300
ResolutionUnit - Inch
JpegIFOffset - 54496
JpegIFByteCount - 6955

[treebeard]

The bricks look different to me. The images look less noisy and distorted. They also look much sharper and clearer. What type of lighting was there in the newspaper ads shots?

[PBandJ]

the ads were using natural light in the basement. I know.. but I'm not allowed to tape them to another wall
the f4 look pretty blurry to me, but i don't know if the best of these lenses does that, or only the duds.

[johnyates]

It is the nature of lenses to be less sharp in the corners than in the center, especially wide open. This is borne out by your testing. Most "real" pictures are composed so that the subject is not in the extreme corners, so this corner softness is not a big deal.

If you experiment with different f-stops, you'll find that the sharpness improves with stopping down. Usually optimum sharpness is obtained 2 stops or so down from wide open. This is what people call the "sweet spot". If you stop down further, you'll get more depth of field, but sharpness will decrease due to diffraction.

I suggest you find your sweet spot and go out and take some real pictures and see if they are sharp enough in the subject area. If there is a sudden drop off of sharpness, or one side of the frame is considerably less sharp than the other, then you have a problem. Otherwise you're fine.

You can't expect corner to corner razor sharpness from a consumer zoom. I suspect that if you shipped it back to Sigma for evaluation, they'd tell you your lens was performing within specifications.

[Pheo]

The UWA lenses are likely to be significantly less sharp at the edges. I would personally compare against the tests at somewhere like DPReview, but I'm not too concerned, these are the far corners of the lens after all.

[Louicio]

Mine is the same =)

[calicojack]

I'll second johnyates' response. Throw the ads out, turn and walk away from the brick wall and take the lens out to where it's meant to be. It's not a flat field (+/or) macro lens. You don't necessarily need the wide open expansive landscapes but you do need average subjects (I so wanted to say real subjects, but stopped myself).
Go for a walk in a residential area and snap a few wide shots of houses or parks or playgrounds or ??? You've been watching the Sigma 10-20 thread for a while so you probably have a feeling for some of the strengths of ultra wide angle lenses (you need an interesting foreground as well as a mid and far. Go for it. Get a few examples of potential lens strengths and then analyze them.

[JinDesu]

Erm, why do you choose F4 and F16? F8 should be sharper than F16.

But what this shows is that there is field curvature, and when you focus on the middle of the wall/ad, there is not enough depth of field to include the corners. At F16, they are fully in focus.

[Edgar_in_Indy]

My 10-20mm is sharp at pretty much any focal length or aperture, but I can't say that I've every really pixel-peeped the extreme corners. I'm at work right now, but when I get home I'll go through my pictures and look at some of the corners.

In the meantime, here are a couple pics from my 10-20mm that I've posted before (and therefore I already have them uploaded). They're both shot handheld (at fairly slow shutter speeds) at 10mm and f4, but I think they do a good job of demonstrating how sharp the lens is across most of the frame, even wide open at the extreme wide angle. Click on the pictures to download the full-size 16MP image.

Unfortunately, neither of the pictures is suitable for pixel-peeping the corners. (But like somebody else pointed out above, you probably won't be too worried about the extreme corners in most pictures).

[tibbitts]

Based on experience with a couple of 10-20mm 4-5.6 Sigmas, the issue is inconsistency from right/left top/bottom at the same aperture. You absolutely cannot expect the lens to do well in the corners of a flat field at f4. So just at first glance I'd say you have a good lens.

But don't test by using auto exposure, auto-iso, or handheld at low shutter speeds. Set for raw, lowest ISO, manual exposure, clamp the camera to your heftiest non-column-extended tripod on a solid surface, and use whatever type of mirror delay/lock your camera has.

In real life you aren't going to shoot newspapers or (close-up) brick walls with this lens. Try using more typical scenes for testing.

As far as f16 vs. f8 etc., for my use f11-f16 gives the best results. Maybe f8 in theory is better but most of my zooms are happy at smaller apertures. Maybe they don't have that last ounce of center sharpness but the overall image at f11-16 is as good - even at over 100% magnification - as at f8 or some other theoretically less diffraction-bound aperture. Now, my tiny-sensored p&s camera, on the other hand, is fuzzy everywhere except wide open - not sure if that's diffraction or if something else is going on.

Paul

[vodanh1982]

Sigma AF 10-20mm f/4-5.6 EX DC (Pentax K) - Review / Test Report - Analysis

It is normal that your lens is soft at corners at f/4. If you need better corner sharpness, go for Sigma 8-16mm.