# 1DX Artificial Light, 12fps, Image Strangeness



## amendegw (Jul 9, 2014)

Shot a rodeo the other evening. When the artificial lighting came on, I started getting strange exposures on my images. Only at 12 fps. Several white balance settings - same issue. Next day I tested in very lighting conditions and it appears that the artificial light is the culprit. Has anyone else seen this? And what could be causing it?







TIA,
...Jerry


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## ajfotofilmagem (Jul 9, 2014)

Fluorescent lamps "blink" in a 60hertz cycle. and the color of the light varies during each restart and shutdown. When shooting with shutter much faster than 1/60 you see part of the cycle and the colors are changed. In practice speeds up to 1/120 should be fine.


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## Northstar (Jul 9, 2014)

amendegw said:


> Shot a rodeo the other evening. When the artificial lighting came on, I started getting strange exposures on my images. Only at 12 fps. Several white balance settings - same issue. Next day I tested in very lighting conditions and it appears that the artificial light is the culprit. Has anyone else seen this? And what could be causing it?
> 
> 
> 
> ...




Jerry...It's most common in older fluorescent lighting at faster shutter speeds...and it's normal. I've had it happen many times with my 1dx. Newer more modern lighting is much better.

The article below explains the problem in an easy to understand way...(link below)

"This article will hopefully explain the difficulties associated with photographing under fluorescent light and advise on how best to deal with the problem.

Fluorescent light bulbs emit photons as electricity excites the atoms inside them. Our homes and businesses are powered by alternating current (AC). This type of current is continually reversing polarity in a cycle known as a sine wave.

As the current goes from zero to positive to zero to negative and back, the changing voltage causes the excited atoms in the fluorescent tubes to emit light of different intensity and different wavelengths. This results in a light source of continually changing brightness and color temperature"

http://johnbdigital.com/lenses/fluorescent/fluorescent_lighting.php

Take care, 
North


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## amendegw (Jul 9, 2014)

Thanks for the replies. The lighting did not appear to be fluorescent (round & there appeared to be some sort of filament - the kind you normally see at stadiums). Shot at 1/640 sec. I wish I had the presence of mind to have tried a slower shutter speed. When I chimped the shots my primary suspect was white balance).

The question remains... why would this occur only at 12fps, not at 3fps or single shot?

...Jerry


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## ajfotofilmagem (Jul 9, 2014)

amendegw said:


> Thanks for the replies. The lighting did not appear to be fluorescent (round & there appeared to be some sort of filament - the kind you normally see at stadiums). Shot at 1/640 sec. I wish I had the presence of mind to have tried a slower shutter speed. When I chimped the shots my primary suspect was white balance).
> The question remains... why would this occur only at 12fps, not at 3fps or single shot?
> ...Jerry


All lamps used in stadiums are fluorescent except some ultra modern stadium that is already using LED. 
Photo number 3 has more natural colors (by chance). When you shoot 3 frames per second or single shot, you can (by chance) more natural colors, depending on the exact moment of shooting.


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## amendegw (Jul 9, 2014)

> All lamps used in stadiums are fluorescent except some ultra modern stadium that is already using LED.



Chuckle! By no means an ultra modern stadium!

...Jerry


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## Max ☢ (Jul 9, 2014)

ajfotofilmagem said:


> All lamps used in stadiums are fluorescent except some ultra modern stadium that is already using LED.



This is not correct! the vast majority of stadiums are illuminated with HID (High Intensity Discharge) lamps of the non-fluorescent type. The common fluorescent tube doesn't have a sufficiently high light output for this kind of application while the standard high-pressure mercury fluorescent (HID) lamp has such poor color rendering properties and low efficiency that it is used in only the most amateurish venues.
In the USA, the most common types of sources used in sport/stadium lighting applications are the sodium-scandium iodide and the rare-earth halide lamps while in Europe sodium-thallium-indium iodide and rare-earth halide lamps prevail. Like fluorescent tubes, all these HID lamps suffer also from flickering issues when operated on conventionnal ferromagnetic ballasts ran at mains frequency. Newer pro-grade installations (e.g. olympic and FIFA cup stadiums) are provided with high-frequency or square-wave electronic ballasts driving rare-earth filled HID lamps which both reduce color flicker down to an imperceptible level suitable for HDTV and slomo video recordings.

From the OP's pictures, I'd juge that the venue where he shot the photo sequence was illuminated with a standard lighting installation using transformer ballasts and sodium-scandium iodide lamps, which is the most common combination used in high-power white-light installations in the US. The issues with photo recording under this condition is the same as under fluorescent tube light although the color cycles are different. This subject has been already treated in details in this thread: http://www.canonrumors.com/forum/index.php?topic=21542.0;topicseen


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## amendegw (Jul 9, 2014)

> ...This subject has been already treated in details in this thread: http://www.canonrumors.com/forum/index.php?topic=21542.0;topicseen



@Max, Thanks so much for that detailed reply. The discussion you referenced pretty much describes my observation perfectly. And the URLs linked go into further detail, including recreating the observation at high burst rates.

...Jerry


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