You should download a free EXIF reader if you want to research images online. It will tell you everything about the image setting, so long as the owner left the EXIF intact.
For the Moon image:
Standard Information
Make: Canon
Model: Canon EOS 40D
Software: Adobe Photoshop CS3 Windows
ImageSize: 900x600
CreateDate: 2008:08:15 23:13:59-05:00
ModifyDate: 2008:08:15 23:13:59-05:00
DateTimeOriginal: 2008:08:15 22:33:42.00-05:00
ExposureTime: 20"
Aperture: F8.0
MaxAperture: F4.0
CircleOfConfusion: 0.004 mm
HyperfocalDistance: 4.19 m
ExposureProgram: Manual
ExposureBiasValue: 0
MeteringMode: Center-weighted average
Flash: Off
ISO: 400
WhiteBalance: Custom
FocalLength: 12.0mm
FocalLength35efl: 12.0mm (35mm equivalent: 83.9mm)
ColorSpace: sRGB
Contrast: +40
Saturation: 0
Sharpness: 25
The Porch light image:
Standard Information
Make: Canon
Model: Canon EOS 40D
Software: Adobe Photoshop CS3 Windows
ImageSize: 900x600
CreateDate: 2008:08:15 23:16:16-05:00
ModifyDate: 2008:08:15 23:16:16-05:00
DateTimeOriginal: 2008:08:15 22:31:08.01-05:00
ExposureTime: 13"
Aperture: F8.0
MaxAperture: F4.0
CircleOfConfusion: 0.004 mm
HyperfocalDistance: 4.19 m
ExposureProgram: Manual
ExposureBiasValue: 0
MeteringMode: Center-weighted average
Flash: Off
ISO: 800
WhiteBalance: Custom
FocalLength: 12.0mm
FocalLength35efl: 12.0mm (35mm equivalent: 83.9mm)
ColorSpace: sRGB
Contrast: +40
Saturation: 0
Sharpness: 25
My guess is, one artifact is on one side and the other reversed, cause ultra wide lens have a radical shape, looking like a rounded cone, not a low rounded hill in cross section. These artifacts only show up at certain angles also. If you put the light source right in the center, you get nothing, put the light source out of the frame, but the light still hitting the glass, nothing. You can also get them in daylight if shooting toward the sun. Look at pictures of streetlights taken and night and you can tell by the number of points, how many leaves are in the iris of the lens. The Tokina is a relatively cheap ultra wide, although well made. Mine was also an earlier model with older coatings.


