Green band (fixed-pattern noise) in photos with Canon 5D Mark IV
Aug 2, 2017
TLDR;
- Photos from Canon 5D Mark IV show a band (fixed-pattern noise).
- Canon Factory Service Center said unit is ok.
- Looking for confirmation that unit is defective and suggestions for what to do to convince them of the problem and get it repaired/replaced.
Problem
I recently noticed that long exposures taken at higher ISOs with my Canon 5D Mark IV (purchased in Oct 2016, still in the warranty period) demonstrate a green band close to one edge.
This is quite visible in under-exposed images that are edited in Lightroom to increase the exposure (starts showing up with +1-stop, often when coupled with other changes).
Sample Images
Here's an Imgur album with a few example images showing the problem (deliberately edited to make the problem more obvious). The band is typically faintly visible in the original image and in almost all cases, starts becoming more obvious as I edit the photo.
5DIV, 200s, ISO 800, f/16 Exposure +0.66, Dehaze +100 in Lightroom to show green band at bottom
5DIV, 420s, ISO 800, f/16 Dehaze +100 in Lightroom to show horizontal green band along bottom edge
5DIV, 120s, ISO 640, f/11 Exposure +3, Dehaze +100 in Lightroom to show vertical green band along right edge
The full set of images from the 5DIV and the 70D (RAW and JPEGs) can be found here (Dropbox).
So Far…
I contacted Canon Customer Support and after exchanging a few emails they asked me to ship the camera to a service center After about 1.5 weeks, the body was shipped back and the accompanying document detailing service details said:
Your product has been examined and it was found that the product performed according to specifications. The unit was cleaned and checked. Product functions were confirmed. **note: Please shoot the image on with proper exposure and avoid the extreme exposure adjustments with software.**.
I should note that the test images I'd sent them were deliberately under-exposed to make the problem obvious. And I personally wouldn’t have considered an post-processing exposure change of 1- or 2-stops to be “extreme" when editing RAW images from a top-of-the-line, full-frame, professional DSLR. In fact, my Canon 70D from 2014 appears to perform better under the same conditions with the same settings - definitely more noise but no banding.
When I first reached out to Canon, I didn't know what this band was. I've since found out about Fixed-Pattern Noiseand the Long Exposure Noise Reduction option in Canon (and Nikon) cameras. Searching online, I see several people seeing this with older Canon cameras but many reviews and forum posts about the 5D Mark IV are raving about the lack of banding To me that's further confirmation that I have a bad unit.
Questions
- Do folks with Canon 5D Mark IVs see this? I'd like to establish if this is common to this model or if it affects my unit in particular.
- Am I wrong in expecting not to have to deal with this on this camera?
- Any suggestions on what to do next to convince Canon that this is a problem with my unit?
Notes
[1] Conditions for reproducing:
- I noticed the problem with a few images from the field, taken at ISO 600.
- I’ve been testing with ISO 800.
- Exposure durations have varied from 150s to 510s.
- I fixed White Balance at 3100K - primarily to be able to easily compare images.
- Long Exposure Noise Reduction is disabled.
[2] The first response was what looked like standard boilerplate asking me to:
- try a different memory card
- clean the lens contacts
- try different lensesI tried all of these these (even though this looks like a sensor problem to me) and continue to see the issue.
[3] Canon covered return shipping.
[4] Long Exposure Noise Reduction
- This was set to Auto on my camera (and I didn't realize what it was for).
- When taking test photos, I found found that it only kicked for exposures that were 450s, and not for longer and shorter ones.
- For those that don't know, when this is enabled the camera will take a second exposure with the same settings as the original, first shot except with the shutter closed. This allows it to compensate for any temporally constant noise - fixed pattern noise. The downside is that it keeps the camera busy for the same duration as the original exposure and so each exposure effectively lasts twice as long which isn't ideal when trying to take, say, 10 minute exposures out in the field.
[5] Forum posts about similar issues (other models):
[6] Canon 5D Mark IV reviews and forum posts about lack of fixed-pattern noise with 5DIV (sorry, none of these had anchors that I could use so you'll have to search the page for 'fixed pattern noise' to find the relevant text):
Note that I'd posted this on Reddit but didn't get too many responses - I'm hoping to get some more help here.