Care to guess why two images shot less than one second apart, in manual exposure mode, look so different? It’s a problem that’s vexed photographers working in certain artificial light environments for decades. It’s flickering of the lights in the area you’re shooting in — your naked eye doesn’t see it, but in some cases, they can rapidly flicker on-off-on at rates up to 120 times per second (or higher). And when you shoot still pictures, this on-off-on repetitive flickering of the artificial lights can wreak havoc on your shots. You never know if your shutter will fire at a “peak” moment, with the lights at their brightest, or a lower moment, when less light will be available to strike your imaging sensor.
This can happen under fluorescent-type office lights, in gyms and indoor sports arenas, and under artificial street lighting. Some lights are wired and work in such a way that this really isn’t a problem and most modern professional and high-level college arenas lit for network television rarely exhibit this. But in older buildings or under less-sophisticated lighting, you can encounter the problem of shooting a series of shots and having significant exposure and white balance differences between one and the next — even if you’ve locked exposure in with Manual exposure mode, and likewise have locked-in a pre-set a white balance such as Fluorescent or even Custom.
Until now, the answer was when you recognized the problem, shoot RAW images, to allow significant WB and exposure corrections at the computer, with minimal quality loss. Or, if you were shooting stationary subjects, you could try to work at slower shutter speeds, such as 1/30th of a second (or thereabouts), which hopefully would encompass an entire flicker cycle of on-off-on with the ambient lighting. None of the “solutions” were terribly appealing.
Canon has introduced technology in the EOS 7D Mark II that addresses the problem — at least in some environments — in a far more effective way. Anti-flicker shooting leverages the power of the camera’s 150,000 pixel RGB +IR metering sensor, to be able to detect the rapid on-off pulsing of certain artificial lights. When you’ve turned this feature on (more on that in a moment), the metering system links to your shutter timing. If/when flickering of artificial lights is detected, the camera reads the rate of flickering and changes shutter timing in two important ways:
- For single shots, it alters actual shutter lag time, so that the actual firing of the shutter coincides with the instant of maximum “peak” illumination during the flickering cycle of the lighting you’re shooting under.
- For continuous shooting sequences, the fps rate and instant of actual firing for each shot are also altered, depending on the flicker cycling frequency detected. Again, this is to match each successive still image to an instant of maximum illumination of the artificial lights.
In either case, photographers who work on-location finally have an answer to the dreaded problem that affected the shooter of the two ice hockey pictures in an older ice arena, at the start of this article.
The new Anti-flicker technology in the EOS 7D Mark II is not active by default and must be turned on in the camera’s 4th Shooting Menu. This is a simple matter of setting this menu item (Anti-flicker shoot) to Enable; there are no sub-menus for further adjustment to the feature.
In those situations where it won’t be needed (an obvious example is shooting in sunlight outdoors), you can turn it off in the same menu (set to “Disable”). You won’t harm the camera by leaving it on when shooting in steady and continuous illumination, but Canon does still recommend turning the feature off when it’s not likely to be needed.
In the “A+” mode (Scene Intelligent Auto or green zone) shooting mode, Anti-flicker shooting is always ready and will kick in if flickering lights are detected. Please note that in A+ mode, the viewfinder warning icon, described below, will not appear.
In the new Intelligent Viewfinder display, the EOS 7D Mark II has a warning icon that can appear on the lower-right corner of the focus screen (it’s in the picture area), with the word FLICKER!. Like almost every item on the transmisssive LCD viewfinder display, this can be turned on or off, allowing users who want or need a simplified viewfinder display the full control to do it. Viewfinder control is in the EOS 7D Mark II Set-up Menu, on the 2nd Set-up Menu screen (Viewfinder Display > Show/hide in viewfinder).
This warning icon does two things:
- Blinks on and off (like a car’s turn indicator) if flickering lights are detected and you’ve got the Anti-flicker shooting feature turned off. Blinking warns you that for best results, the camera is recommending you turn the Anti-flicker feature on.
- Illuminates steadily if flickering is detected, and you already have the Anti-flicker feature turned on. Steady appearance of this icon indicates the feature is being applied, and is a warning that shutter timing and drive speed may change from how you’d expect them to otherwise be (more on that in a moment).
Regardless of whether you’ve turned Anti-flicker shooting on or off in the Shooting Menu, the FLICKER! icon will not appear on-screen unless actual flickering lighting is detected.
All the above assumes you’ve got the FLICKER! warning active in the viewfinder. As mentioned above, in the 2nd Set-up Menu, you can activate the viewfinder’s icon by highlighting it on that menu screen and pressing the SET button to put a check mark above it. To turn the viewfinder icon off, simply repeat the procedure and delete the check mark (it can always be re-activated later).
Important: actual activation of the Anti-flicker shooting feature (in the Shooting Menu) and whether or not the FLICKER! icon appears in the viewfinder are completely independent of one another. In other words, you can have Anti-flicker shooting technology active and still have the icon disabled (it won’t appear in the viewfinder at all, even during Anti-flicker shooting, if it’s turned off in the Set-up Menu).
As mentioned above, the EOS 7D Mark II is the first ever Canon EOS camera with technology to attack this previously vexing problem of flickering lights when on-location for still images taken at moderate to fast shutter speeds. It can be extremely effective at minimizing or even eliminating the problem, but there are a few limits to be aware of:
Works at two detected flicker rates only — 100Hz and 120Hz
The EOS 7D Mark II’s Anti-flicker shooting feature can only correct flicker for artificial lights flashing on-off at a rate of 100Hz (100 times per second) or 120Hz (120 times per second). It’s entirely possible to encounter situations where some or all of the lighting is flickering at other rates and, even if the EOS 7D Mark II detects this, it cannot correct for flicker at any other Hz rates.
Works only for still images — not video
Unlike some competitive cameras, the EOS 7D Mark II only offers detection and correction for flickering lights for still-image shooting. This feature is not available when video is being captured, nor is it possible for still images taken in the midst of a video recording.
Works for viewfinder shooting only — not Live View
Still images taken in Live View cannot utilize the Anti-flicker technology, even if you’ve activated it in the Shooting Menu.
While the feature is very effective at the Hz rates indicated above, there are some conditions where the camera may not be able to correct for the effects of flickering lighting, even if it has been detected. For critical applications and situations, Canon recommends taking test shots before actual images are taken.
Here is yet another answer to the wish-lists for some location shooters, and another reason if you own this camera to try the feature any time you either see the FLICKER! icon appear in the viewfinder, or encounter available-light images with the inconsistencies we saw in the two ice hockey images at the top of this article. To our knowledge, the EOS 7D Mark II is the first SLR ever with anti-flicker technology for still images. Whether you shoot indoor sports, weddings, events, school yearbook images, or similar available-light scenarios, simply turning this feature on can save a lot of head-scratching, and a lot of time correcting images individually in post-processing.
The CDLC contributors are compensated spokespersons and actual users of the Canon products that they promote.
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