RAW out of the box sharpness depending on ISO chosen?

[EvaValk]

Hi, I own a Canon G12 and I discovered that an out of the box RAW image at 800 ISO is more sharp than an out of the box RAW image 100 ISO. See image below.

Both images have been made from a tripod with self-timer and the same aperture (f 5.6)

Both images are converted to TIFF in Lightroom 5.5 without any change (only RAW-converson) and are saved as without any post processing like sharpening.

What could be the reason for the difference?

Maybe it could be the anti-alias filter? I do not know whether that is a static filter or that the cut-off frequency differs per ISO value. Suppose that the cut-off frequency at 800 ISO is higher than at 100 ISO, it could result in a sharper out of the box picture.

Or is it an optical illusion?

Thank you and best regards, Eva

 

[EvaValk]

Image was not vissible in previous view

 

[richsfusa]

Is that a 100% crop of a portion of the original image?

To my eye the sharpness looks about the same in both images. If anything the ISO 100 image appears sharper because there is less digital noise than in the ISO 800 image.

The ISO 800 image does look a little more contrasty...which may make it look a little sharper to some eyes.

Just my opinion.

 

[EvaValk]

Hi richsfus, yes it is a 100% crop of a portion of the original image. On the the division between red and gold I can see the the 800 ISO is sharper.

 

[Plagen]

The actual sharpness is the same but perceived sharpness or acuteness is indeed different. Some amount of noise or graininess increases acuteness. It is very well known effect (google) and is often use in practice by artificially adding noise to some images.

 

[damian5000]

What he said. The noise is actually increasing perceived sharpness here.