Weird Histogram from Aptus 22

[savagegibson]

I'm getting a weird spike in the shadows of my Aptus 22 histograms. I think what I'm seeing are black artifacts mainly in the shadows, but I'm not sure why they are there.

The first image is what the histogram looks like in LC10 before processing. There is no indication of the spike in LC 10 or Aperture but the spike is visible in ACR and in the Tiff it always shows up in Photoshop.

The third image is the odd histogram from the Tiff file in Photoshop. The spike in the shadows shows up regardless of what RAW processing program I use; Photoshop CS3, Aperture, or LC10.

The middle image is a 200% view  of the shadow area of the file that I pulled these histograms from.

For clarification, The Photoshop histogram has been modified to move the left of the histogram a bit to the right so the spike would be easier to see.

Any thoughts?

[deelight]

Hi Savage,

what ASA did you use? Looks like 200 or so.

Could it be that you somehow applied too much sharpening when processing the RAWs? So the amount of 100% black artefacts would increase and become a more significant number.

I also use A22 and sometimes also see the black artefacts but usually simply change to a lower ASA if they are supposed to become a problem. The spike never appeared in my histogram though, at least I did not notice one...

Best,

Clem

[savagegibson]

They were shot at ISO 50. That's just one of the reasons I think this is so odd.

Also, I don't know if this is relevant but I'm shooting with a Fiji GX680III and the Kapture group adapter.