{"id":11815,"date":"2026-09-22T05:04:29","date_gmt":"2026-09-22T03:04:29","guid":{"rendered":"https:\/\/www.brokenmount.com\/bm\/2026\/09\/22\/clearing-up-confusion-electronic-first-curtain-shutters-are-mechanical-when-it-counts\/"},"modified":"2026-09-22T05:04:29","modified_gmt":"2026-09-22T03:04:29","slug":"clearing-up-confusion-electronic-first-curtain-shutters-are-mechanical-when-it-counts","status":"publish","type":"post","link":"https:\/\/www.brokenmount.com\/bm\/2026\/09\/22\/clearing-up-confusion-electronic-first-curtain-shutters-are-mechanical-when-it-counts\/","title":{"rendered":"Clearing up confusion: electronic first curtain shutters are mechanical when it counts"},"content":{"rendered":"
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\n\tThere are downsides to Electronic First Curtain cameras, but you\u2019ll only see them at the extremes<\/p>\n

\"TheMitchell Clark<\/span><\/figure>\n<\/section>\n
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The Canon EOS R8 II is the latest camera to keep size down by adopting an electronic first curtain shutter design. This isn\u2019t the same thing as full electronic shutter and it has very few downsides, so here\u2019s how it works and what those downsides are.<\/p>\n<\/div>\n<\/section>\n

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Perhaps an easier way to understand EFCS is to think of it as Mechanical Second Curtain Shutter. The exposure is started electronically but a normal mechanical shutter then comes down to end the exposure, meaning that, unlike full electronic shutter, you can end your exposure very quickly, rather than being limited by readout speed of your sensor.<\/p>\n

This means EFCS doesn\u2019t have the significant rolling shutter artifacts (banding under flickering light and distorted moving subjects) that all but the fastest sensors can exhibit. The fast end to the exposure also means it can usually sync with flashes up to the same speed as a fully mechanical focal plane shutter.<\/p>\n

In fact, it can have a benefit over full mechanical shutters, in one regard: because there\u2019s no physical shutter snapping open at the start of the exposure, it eliminates a key source of vibration that can cause shutter shock. Some cameras with full mechanical shutters switch across to their EFCS mode within certain shutter ranges for exactly this reason.<\/p>\n

This is the reason we\u2019ve seen an increasing number of cameras, particularly the ones where the manufacturer has focused on downsizing and on cost reduction. In most instances, EFCS lets you use a smaller, mechanically simpler mechanism, with very little disadvantage.<\/p>\n<\/div>\n<\/section>\n

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The downside<\/h2>\n

It\u2019s not entirely without downsides, though. At very high shutter speeds, where the period during which the shutter is closing makes up a significant proportion of the exposure, you can experience bokeh truncation: part of the bokeh pattern getting chopped off.<\/p>\n

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Sony\u2019s a7C series cameras also omit a mechanical first curtain shutter, helping keep both the size and cost down, compared with the mainline a7 models.<\/figcaption>DPReview<\/span><\/figure>\n

This happens because the physical shutter used to end the exposure sits some distance in front of the sensor, so light can creep around the edge of the shutter blades as it closes. But the electronic first curtain (progressively turning the rows of the sensor on to start the exposure) doesn\u2019t have that gap, so the start of the exposure didn\u2019t have that light bleeding around the edge of the \u2018shutter,\u2019 giving one side of the bokeh a hard cut-off. This results in out-of-focus regions that aren\u2019t as blurred and may not have such attractive bokeh.<\/p>\n

However, this only becomes visible at very high shutter speeds when using lenses with fast enough apertures to significantly blur the background. <\/p>\n

The \u2018hard-edged\u2019 nature of the electronic initiation of the exposure also means that any banding effect (from the fast flicker of LED advertising displays or high-speed sync flash) can end up being better defined and more distracting than with a fully mechanical shutter, again because light creeping around the gap between physical shutter blades and the sensor surface can soften it somewhat.<\/p>\n<\/div>\n<\/section>\n

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For the vast majority of situations though, including flash sync, electronic first curtain (\/mechanical second curtain) shutter, is every bit as good as full mechanical shutter.<\/p>\n

About the Author: <\/span>Richard graduated as a scientist but had a lot more fun writing and shooting for his university magazine. A number of years spent variously as a reporter, writer and editor on science and engineering titles combined his knowledge of science with his interest in images and words. But it was spotting the connections between emission spectra, white balance and all the nonsense he\u2019d taught himself playing around in Photoshop that helped kindle an interest in digital photography. Searching for a camera led to him discovering DPReview and Richard was recruited by Phil Askey in 2007. He\u2019s been combining his love of photography, communication and attention to detail (pedantry?) ever since.<\/p>\n

He has unusually strong opinions about lenses for the APS-C format.<\/p><\/div>\n

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Want to stay up to date on the latest product news and releases?\u00a0Add DPReview as a preferred source to ensure our independent journalism makes it to the top of your Google search results.<\/p>\n

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