645z with high SS speed banding problems, no flash used

**cdd29** · 10-21-2021, 07:45 PM

ok, time to troubleshoot. For fun, I thought I'd take out the old 645z to my daughter's marching band practice to see how badly it would do sports. It started doing something unexpected. At higher shutter speeds, I'm getting black banding across frames. These were taken as continuous 3FPS. Anything higher that 1/200 started showing banding in different frames I took as a bust. As an experiment, I tried a faster shutter speed and they got worse. The first three were shot at . f/5.6, 1/1000. ISO 12800. Second set was shot at f/1250, 5/5.6, ISO 12800. Started out at 6400 ISO as it was dark and this isn't a fast lens (150-300) f/5.6. Those are exaggerated settings of course to produce the banding, as at slower speeds the banding is less obvious. I wasn't using a flash, so it wasn't flash sync problems. Some kind of high speed shutter sync problem. Anyone run into this?

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Last edited by cdd29; 10-22-2021 at 05:23 AM.

**Ed Hurst** · 10-21-2021, 08:39 PM - **1 Like**

Just a hunch - was there fluorescent lighting there? Could it be the frequency of the strobing of the lights interfering with the shutter speed.

**TDvN57** · 10-21-2021, 09:46 PM - **1 Like**

I've experienced the same with LED lights that are not "calibrated" for photography or Video.

**ProfessorBuzz** · 10-22-2021, 05:18 AM

Betting it's high intensity metal halide ballasted lights.
The 645Z has a Flicker Reduction setting in the menu - you can change to 50Hz or 60Hz, and that might help, but it may not solve entirely.

**cdd29** · 10-22-2021, 05:26 AM

Must have been the stadium lights. I went out to my car, grabbed the camera & tried to replicate the issue in broad daylight but it wouldn't do it. Strange thing is I've shot in the same stadium, same camera before and not had any trouble.

**kaseki** · 10-22-2021, 12:06 PM

Y'all are on the right track. If we imagine a high shutter speed as two slightly separated curtains crossing the focal plane, they take a period of the order of the flash sync speed to get across. It is only necessary for the lights to be modulated at some rate of that order for the banding to appear. In 60 Hz countries the light is modulated at 120 Hz; in 50 Hz countries 100 Hz. (Japan gets both, depending on location.) Depth of modulation depends on the thermal capacity of the emitter. Arc lamp plasmas have very low thermal capacity, so should show the highest modulation. The solution, unfortunately, is likely to be an electronic shutter that opens and closes the entire array at once. There will still be a mismatch between average lighting measured to set an appropriate combination of aperture, time, and ISO, and the peaks and valleys of the emitted light. Three phase lighting using triads of emitters would have very low modulation. Well filtered LED power would solve the issue.

10-22-2021, 05:26 AM	#5
cdd29 Loyal Site Supporter Join Date: Sep 2016 Location: Southern Indiana Photos: Gallery Posts: 961 Original Poster	Must have been the stadium lights. I went out to my car, grabbed the camera & tried to replicate the issue in broad daylight but it wouldn't do it. Strange thing is I've shot in the same stadium, same camera before and not had any trouble. Last edited by cdd29; 10-22-2021 at 06:24 AM.

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10-21-2021, 08:39 PM - 1 Like	#2
Ed Hurst Site Supporter Join Date: May 2010 Location: Sydney Posts: 1,657	Just a hunch - was there fluorescent lighting there? Could it be the frequency of the strobing of the lights interfering with the shutter speed.

10-21-2021, 09:46 PM - 1 Like	#3
TDvN57 Loyal Site Supporter Join Date: Jul 2011 Location: Berlin Photos: Gallery Posts: 1,149	I've experienced the same with LED lights that are not "calibrated" for photography or Video.

10-22-2021, 05:18 AM	#4
ProfessorBuzz Loyal Site Supporter Join Date: Feb 2018 Posts: 1,903	Betting it's high intensity metal halide ballasted lights. The 645Z has a Flicker Reduction setting in the menu - you can change to 50Hz or 60Hz, and that might help, but it may not solve entirely.

10-22-2021, 12:06 PM	#6
kaseki Loyal Site Supporter Join Date: Dec 2017 Photos: Gallery \| Albums Posts: 1,138	Y'all are on the right track. If we imagine a high shutter speed as two slightly separated curtains crossing the focal plane, they take a period of the order of the flash sync speed to get across. It is only necessary for the lights to be modulated at some rate of that order for the banding to appear. In 60 Hz countries the light is modulated at 120 Hz; in 50 Hz countries 100 Hz. (Japan gets both, depending on location.) Depth of modulation depends on the thermal capacity of the emitter. Arc lamp plasmas have very low thermal capacity, so should show the highest modulation. The solution, unfortunately, is likely to be an electronic shutter that opens and closes the entire array at once. There will still be a mismatch between average lighting measured to set an appropriate combination of aperture, time, and ISO, and the peaks and valleys of the emitted light. Three phase lighting using triads of emitters would have very low modulation. Well filtered LED power would solve the issue.