Long exposures create red noisy glow.. but only with one of my lenses. Why?

Question

I recently started having a problem with long exposure (30 sec +) photos having a pattern of red noise. The problem started in the middle of a camping trip - long exposure pictures looked fine one night, and a couple nights later they looked like this (f/3.5, 72 sec, ISO-1600, D7000, Nikkor 18-200 f3.5-5.6):

I've narrowed down the problem to be related to the specific lens - here's a picture I took upon returning home using the same lens (lens cap on, view finder covered). You can see the same red noise pattern (f/3.5, 30 sec, ISO-1600, D7000, Nikkor 18-200 f3.5-5.6):

When I switched to a different lens (lens cap on, view finder covered, same settings), the problem disappeared (f/3.5, 30 sec, ISO-1600, D7000, Tamron 28-75 f2.8):

Any ideas what's going on? Is my lens damaged somehow? My first thought was that the mount was bent and letting light into the sensor somehow, but the pattern seems very consistent regardless of the camera's orientation relative to external light sources. I'm baffled.

Answer 1

This is a known issue with the Nikon 18-200 ƒ/3.5–5.6 VR lens. Some people have reported a simple workaround, some others report the workaround doesn't work.

The Problem

Apparently the VR mechanism inside the lens emits some infrared radiation, enough that it can be picked up in some cases, especially in long-exposure photography. Although, 30 seconds at ISO 1600 doesn't seem particularly long shutter or high ISO to me for what appears to be twilight shots in your example.

The (Apparent) Solution

When taking long-exposure images with this lens, make sure to set both the VR to "off", and to set the lens's switch to "M", not just M/A. Setting the camera body's autofocus switch to "M" doesn't seem to help or make a difference at all.

Some people report that Long Exposure Noise Reduction helps or eliminates the problem (at the expense of taking twice as long to take the image). YMMV.

See also these (long) discussions at dpreview.com. Be prepared to sift through lots of side-diversions and speculations about amp glow, and admonitions to make sure the viewfinder is covered, which is clearly not the problem.

• Design flaw in all nikkor 18-200vr's- All models are defective — I think this is the thread that started it all. Sample image:
  
  ^{Demonstration of problem by dpreview.com user MaxKPhoto. D300, 18mm, 28.5min @ ƒ/3.5, WB incandescent, ISO 200, auto noise reduction.}
• Lens VR unit IR leakage affects long exposures - cont'd.
• red saturation on a nikon 18-200 right side during long exposure. Sample images demonstrating the issue:
  
  
  ^{Demonstration of problem by dpreview.com poster 86reddawg. 18-200mm ƒ/ 3.5–5.6 on D5000, 4+ minutes.}