Fuji X-T2 Banding Or Flickering Issue

Example of an image where flicker was present using the X-T2 and, in this case, the Fuji 56mm f/1.2 lens
(click to enlarge)

The other day when I was conducting tests for the accuracy and consistency of autofocus as compared to manual focus, 2/5 of the way through the test, my X-T2 experienced a severe case of banding or flicker visible on the LCD and in the resultant images.  You can see an example above.  I remain a bit baffled as to why this happened.  You can read about the autofocus tests here.

Just to recap, the camera was securely attached to a tripod and I tested various lenses as to how accurately, consistently each lens would focus and then compared the camera/lens combination's autofocusing ability to manually focusing each of the lenses. The target was a page from a sale catalog shown above.  As for lighting, I had one General Electric Reveal incandescent bulb in a reflector shining on the target. There was no fluorescent lighting anywhere, which are know to cause this phenomenon.  There was some residual daylight that came in through the room windows but it low level as it was a very overcast day, hence using some auxiliary lighting to reach a high enough shutter speed in order to ensure there was no camera movement possible, which would nullify the tests.

This is a typical image from the 16-55mm f/2.8 lens showing no flicker/banding (click to enlarge)
The only difference between the top image and this one is the lens used.

The first two lenses I tested, the 16-55mm f/2.8 and 18-55mm f/2.8-4, were made and there was no banding or flicker seen.  The next lens to test was the 56mm f/1.2, followed by the 35mm f/2 and finally the 50-140mm f/2.8.  All tests with these three lenses showed this banding/flickering.  The bands/flicker was easy to see as I stood behind my camera and looked at the LCD.  It immediately caught my attention.  At that point, I didn't know if it was just on the LCD or it would also appear in the resultant images. Later, banding was seen in the images.  Looking at the LCD while the camera was before me, the horizontal bands of dark/light moved from bottom to top of the LCD.  It appears as though it is the same type of issue one would see when a movie or video cameras' refresh rate is out of sync with a computer monitor or TV.  Horizontal bands moving across the screen. Additionally, the setting on my camera's menu is set for "Auto" flicker reduction.  But, there shouldn't have been any flicker in the first place as there was no fluorescent lighting at all.  Only the Reveal incandescent light bulb and some residual daylight, as I said.

The other baffling issue was that this flicker did not occur with the first two lenses.  Only after a period of time when the third lens was attached, did the flicker appear.  Each lens was tested in three ways with twenty exposures for each test, meaning there were 60 exposures for each lens.  At the time the flicker started, 120 exposures had been made.  I don't know if there was some sort of heat build-up but 120 exposures is a piece of cake for this camera.  The only other thing I could think of, besides a camera malfunction or defective electronics, is that the GE Reveal bulb has some sort of defect or some sort of pulsating light pattern, but I can't find anything on the Internet indicating this has been seen by others.

If anyone has an idea as to why this occurred, I would love to know.  I'm sure other readers would like to know as well.  I've seen some comments on forums about X-T2 flicker, but this situation seems a bit different.  This is a bit disturbing as I don't know the source of this issue, camera, bulb, or otherwise. 

Fuji, if you are reading this, please contact me and advise.

In the end, I'm going to have to go back and try to recreate the circumstances under which the banding/flickering appeared to see if I can replicate it. If it does appear, then I'll go about trying to determine the cause.  I'll let you know.

Thanks for looking. Enjoy! 

Dennis A. Mook 

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