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DPChallenge Forums >> Hardware and Software >> Is the sigma 10-20mm supposed to be this soft?
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Showing posts 1 - 7 of 7, (reverse)
AuthorThread
 03/10/2010 10:24:13 PM · #1
Im thinking of buying the sigma 10-20mm off someone on craigslist. They've sent me a few sample shots, but they seem a little blurry. Im wondering if this is normal, of if this lens is a dud.

//i4.photobucket.com/albums/y110/kawana/IMG_2010_03_09_8317.jpg
//i4.photobucket.com/albums/y110/kawana/IMG_2010_03_09_8315.jpg

I know pixel hunting always makes it seem worse, and its the printed image that matters, but still. Should it be this blurry?
 03/10/2010 10:31:38 PM · #2
My copy of that lens is pretty sharp. Not sure why those images look like they do. If that is the true rendering of the lens for sale, I would pass.
 03/10/2010 10:33:14 PM · #3
whats the best aperture to test this lens at? F8? Im gunna get him to take a few more, and send me the raw files.

Message edited by author 2010-03-10 22:37:14.
 03/10/2010 11:09:58 PM · #4
I looks pretty good to me, though I can see it's a little softer near the edges. This is as I would expect of a wide lens. Perhaps my view is a result of my own use of relatively inexpensive lenses to this point.
 03/10/2010 11:54:48 PM · #5
Yeah, be careful for sure. Sigma is know to have, not the best quality control. I would suggest finding one you can try, before you buy. I have actually read about people trying 3 copies, before finding a good one. Don't get me wrong, this seems to be the worse case I found. Still, it makes you think. I do know if you get a good copy, you will be pleased. Do get him to retake some shots, at different apertures, focal length and distances. Oh and with a tripod. Then you should be covered, reviewing the raw images. If he refuses to help ease your wonder, keep on walking.
Good luck!
 03/11/2010 03:00:35 AM · #6
that doesn't seem so bad to me, but then again I'm looking at what... a 1200 pixel image?

Shoot with a tripod at f/8-f/11, that will give a better indication than a wall, which you may not have been parallel against to get a totally unbiased product.
 03/11/2010 11:14:31 AM · #7
I don't think they look bad either.

FWIW here is the information on the image he took of the ground.

BTW I saved the images because they are both good texture images, hahaha

[Overview]
File name: I:\Useable Photos\Textures\IMG_2010_03_09_8315.jpg
File type: JPEG
File size: 829.6 KB
Creation date: 3/9/2010 16:04
Last modification: 3/11/2010 11:10
Make: Canon (//www.canon.com)
Camera: Canon EOS DIGITAL REBEL XSi
Lens: Sigma 10-20mm F4-5.6
Software: Firmware Version 1.0.9
Dimension: 1415 x 944 px (1.3 MP, 3:2)
Focal length: 10 mm (equiv. 16 mm)
Aperture: F4
Exposure time: 1/200"
ISO speed rating: 200/24°
Program: Manual (Manual)
Metering Mode: Spot
White Balance: Auto
Focus Mode: Single-point AF
Noise Reduction: Off
Flash: Flash did not fire, compulsory flash mode

[Image]
Manufacturer: Canon
Image input equipment model: Canon EOS DIGITAL REBEL XSi
Orientation of image: 0° (top/left)
??? (0001):
Image resolution in height direction: 72 dpi
Unit of X and Y resolution: inch
File change date and time: 2010-03-09 16:04:38
Y and C positioning: Co-Sited
Exif IFD Pointer: 0x000000C4

[Camera]
Exposure time: 1/200"
F number: F4
Exposure program: Manual
ISO speed rating: 200/24°
Exif version: Version 2.21
Date and time of original data generation: 2010-03-09 16:04:38
Date and time of digital data generation: 2010-03-09 16:04:38
Meaning of each component: YCbCr
Shutter speed: 7.63 Tv (1/197.4")
Aperture: 4 Av (F4)
Exposure bias: ±0 EV
Metering mode: Spot
Flash: Flash did not fire, compulsory flash mode
Lens focal length: 10 mm
Manufacturer notes: 0x00000296
User comment:
DateTime subseconds: 0.03"
DateTimeOriginal subseconds: 0.03"
DateTimeDigitized subseconds: 0.03"
Supported Flashpix version: Version 1.0
Color space: sRGB
Image width: 4272 px
Image height: 2848 px
Interoperability IFD Pointer: 0x00002522
Focal plane X resolution: 4865.6 ppi
Focal plane Y resolution: 4876.71 ppi
Focal plane resolution unit: inch
Custom image processing: Normal process
Exposure mode: Manual exposure
White balance: Auto
Scene capture type: Standard

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