I recently discovered a small problem. I took a couple of test shots without a lens and with the mount cap on (therefore complete darkness) with varying ISOs (RAW, manual mode, everything else constant). I found that at higher (3200) ISOs, obvious green/blue specks appear but at lower (50, 100) ISOs, they're non-existent/very small. Oddly, when I compress it to JPEG, the spots become extremely difficult to spot so no picture is included.
Any idea what the problem is?