VPN/HN

I've had my Pentax K10D for just under two months now and shot approx 4400 images with it. I saw a bit of vertical banding in the darkness on a moonshot once as I accidentally pushed the levels way too high in PP, that was it. Since then I've updated the firmware to 1.10 and I was pretty firm in my opinion that those who had visible banding now either had faulty cameras, did something really funky to them, or both. Another issue on the dpreview forums has been the appearance of crosshatch, or horizontal banding when the Pentax D-BG2 battery grip was installed. My grip had been on my camera from day one and I hadn't seen any banding from it.

Tonight I put my camera to the test.

I put on my pinhole body cap, both to under-expose enough and to make sure these artifacts wasn't somehow caused by a lens. I pointed this contraption towards a brightly lit sheet of paper and shot in DNG. 1/4s, ISO 100, 400, 800 and 1600. I shot 8 series; with the grip on/off, SR on/off and NR on/off in all combinations. These images are the ISO1600 versions, pushed around 4 stops, resized to 800x600 and saved as JPEG. No other processing has been done except what Photoshop does automatically in the way of contrast, saturation and so on when importing a DNG. Link to one of the original DNGs here: (Grip ON, SR ON, NR ON).

Grip ON, SR ON, NR ON:

Grip ON, SR OFF, NR ON:

Grip ON, SR ON, NR OFF:

Grip ON, SR OFF, NR OFF:

Grip OFF, SR ON, NR ON:

Grip OFF, SR OFF, NR ON:

Grip OFF, SR ON, NR OFF:

Grip OFF, SR OFF, NR OFF:

1:1 crop from the middle of the Grip ON, SR OFF, NR OFF ISO1600 image:

The ISO100 version of the Grip ON, SR OFF, NR OFF, naturally even more pushed:

Conclusion

Yep, my camera has them too, both bandings, in all ISOs. They are not caused by, or visibly affected by, neither Shake Reduction nor Noise Reduction - with the possible exception that NR may mask or remove the horizontal noise. The horizontal bands are definitely caused by the battery grip.

However, due to the fact that I had to go to these rather extreme measures to find these artifacts is the main reason why this has become a heated debate in forums. It is quite possible to shoot thousands of very nice shots with this camera (and grip) and never ever notice this banding. Others, either trying to save an under-exposed shot or simply attempting to use the maximal Dynamic Range in the camera may encounter them on a daily basis. Either way, it would be nice if Pentax could fix this issue somehow, if possible via firmware. And yes, I know I need to clean my sensor. Hm, maybe I could make that a sensor cleaning system test? :-)
Barring that, next test is to see if I can make the banding appear in more reasonably exposed images. There are a few reports of this happening, but it seems to be a hit and miss affair, maybe there's something specific that's triggering it, or just camera sample variations. We'll see. Meanwhile, feel free to test your own cameras.

Link to a method for removing VPN

Other cameras

In parting, just to put things in perspective - here are two shots from my trusty old Olympus 2100uz, pushed less than two stops (these subjects were visible in the original images, the K10D shots above were almost totally black before I pushed them). A camera which I have shot tens of thousands of shots with over a period of six years and never noticed any banding artifacts:


Yes, they are taken with an IR filter which I only got recently. It was the only way I could more or less accidentally under-expose enough to have something to push several stops...

Thom Hogan's sample image from a Nikon D80 which has both VPN and amp glow:

An image from a Canon EOS 400d (Digital Rebel XTi) - HN and amp glow, using Thom Hogans' method to test for amp glow:

And the same test done on my Pentax K10D:

Thom Hogan's amp glow test

Reportedly, this is his test for amp glow in the Nikon D80. Adapt as needed, for your camera. Apparently it works to find any kind of artifacts:

  • Reset your D80 so that the camera defaults are in place.
  • Set ISO 1600.
  • Set Manual exposure mode.
  • Set JPEG Fine Large as the image quality.
  • White balance and other settings should be Auto (because of #1).
  • Put a lens cap on your lens or a body cap (no lens in place) on the camera.
  • Perform a series of exposures in the following sequence: 1/60, 1/30, 1/15, 1/8, 1/4, 1/2, 1s, 2s, 4s, 8s.
  • Start Photoshop (or Photoshop Elements).
  • Open each exposure and visually examine with the exposure at Fit Screen viewing mode. If there is any purple at the top in the 1000-1600 pixel axis (horizontal) note that.
  • Now run Auto Levels on each exposure. You may not have seen purple before but you may see it now. Again, note that particular area at the top between 1000 and 1600 on the horizontal axis.