Electronic front curtain shutter and cut bokeh. Enlarge Image... A Sony a7M3 camera with a lens was used for the picture. 7Artisans 50mm 1: 1.05 APO and EFCS enabled.
Some mirrorless cameras may use EFCS (Eelectronic FRONT CUrtain Shutter) electronic front curtain shutter. In general, this is a useful feature that reduces shutter lag, tent-shock, simplifies high-speed shooting, and reduces overall shutter noise.
But it has a very unpleasant feature. When using high-aperture lenses (which have a large aperture) at very fast shutter speeds, you can observe a significant deterioration in bokeh.
Unsharp discs in this case are, as it were, cut off. The bokeh becomes clogged with 'scales' and generally deteriorates significantly.
Examples of 'cut' discs of blur in bokeh due to the influence of EFCS, short excerpts and wide aperture:
Unsharp discs are cut strictly from the bottom / top and left / right, depending on the orientation of the camera and the near or far zone of confusion. In the normal landscape (horizontal) orientation of the camera, the discs of unsharpness in the background are clipped from below, and the discs of confusion in the foreground are clipped from above.
For example, my camera Sony a3500 can use EFCS exclusively, with no option to choose only mechanical shutter or only electronic shutter. When using fast lenses with F / 0.95-F / 2.8, the effect is very noticeable in the range of shutter speeds of 1 / 4000-1 / 1600 seconds. In the 1/1600 - / 1000 range, the effect is noticeably weak. At shutter speeds longer than 1/1000 of a second, this effect disappears completely.
This effect is associated with parallax due to the different heights of the position of the mechanical and electronic shutters above the camera sensor. The electronic shutter, roughly speaking, has zero height (coincides with the plane of the sensor). The mechanical shutter is located much further (higher) from the camera sensor.
The cause of the problem. Picture taken here.
The shorter excerpt and the wider the aperture, the more pronounced this effect is. How to deal with this problem?
- turn off EFCS and use an exclusively full mechanical shutter or a fully electronic shutter. The same recommendation can be found in the instructions for cameras for which you can enable and disable EFCS.
- some cameras may automatically use EFCS or mechanical shutter depending on the desired excerpts.
- lengthen exposure... To do this, you can lower the ISO, close the aperture, use ND filters (including those with variable density), or polarizing filters (or a combination of different filters).
- this effect is practically not manifested at apertures less than f / 4. For example, with a whale lens Sony E 3.5-5.6 / 18-55 OSS (Optical Steady Shot, E-mount) at 55mm focal length and f / 5.6, this effect is not noticeable.
I have a video on this topic on Youtube channel here.
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Material prepared Arkady Shapoval.
yes, the problem is old and well known
classic material on the topic: https://phillipreeve.net/blog/limitations-of-the-electronic-shutter-function/
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Recently I picked up my old Sony a33 from the shelf, which does not have an electronic front curtain shooting mode and was just shocked at how long it takes to shoot a frame on a fully mechanical shutter. You quickly get used to good things.
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An unpleasant feature. It's news to me.
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Likewise. It turns out interestingly that two parallel directions - to a higher aperture ratio and to an electronic shutter - intersect in a not very interesting place. But the higher the aperture, the less shutter speed is needed, and we have already rolled out our lips that we can do without mechanics.
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Since then, on a fully electronic exposure, nothing bad happens. So yes, you can (and should) do without mechanics.
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The effect is manifested precisely with the electronic front and mechanical rear curtain. There is no problem with a fully electronic shutter.
By the way, when shooting at the z5 + 50 / 1.8g with the electronic front curtain, this effect is not noticeable. Most likely it is, it just does not really affect the picture and is not striking. However, on the z5, the shutter speed with the electronic front curtain is limited to 1/2000
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Whoa! Did not know. Colleagues tell me, such a question: I was shooting a portrait on Olympus, lens 45 1.8, a Christmas tree with garlands on LEDs acted in the background. I wanted beautiful lights on the bokeh. In the photo, the lights turned out to be terrible, blown out, white! This was not the case with ordinary bulbs. Is that so for everyone? And can we fight this?
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LEDs have a much higher temperature with a much smaller surface area emitting light. Turn on the light in the room brighter and take the exposure down by 2-3-4 stops.
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Roman, thanks!
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This is the first time I've seen this .. Informative, thanks
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The problem is the sonny cho, all the sonnekos are podzravlyamba xD Fuj does not have this. I checked it at f2.8 at 16-55mm (55mm), the difference with the mechanics, the electronic curtain and the electronic shutter is not noticeable, at the level of the ambient lighting error.
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Both articles describe lenses with an aperture ratio of 1.0. This is slightly more than your 2.8. Plus, you need appropriate images with point light sources - garlands, glare from metal objects or foliage.
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As it is said, it can be seen up to 5.6, so it is not necessary :-) Believe me, I checked
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"This effect is almost non-existent at apertures smaller than f / 4 ... at 55mm focal length and f / 5.6 this effect is not noticeable"
Are we reading the same text? I would make unambiguous conclusions only after checking at least 1.4 with specific highlights in a frame such as a garland at a great distance.
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You can disbelieve as much as you like, it's your right)) Check it yourself :-)
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How will 7Art 55mm1.4 II come to me, I will take another look, especially for you ;-)
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are they already selling the second version?
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Pre-ordered, stuck somewhere at the airport.
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Here's a confirmation shot with Fujifilm X-T3 + 7artisans 55mm1.4, 1/2500, 1.4, 12800
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I was wrong, I used the wrong shutter. Yes, there is a slight clipping at the top.
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So Fuj has everything like the others - at short exposures, either an electronic shutter or a mechanical one.
Quote: "The problem is sonny cho, all the sonobraders are podzravlyamba xD Fuj has no such thing."
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And what, Fuja is organized in a different way than all the others (Sony, Canon, Nikon, Panasonic)? Oh, these fujivods piously believe in the “divinity” of the purchased products.
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You can keep your preconceived opinion to yourself) I say what I see on the screen, especially for people like you, I will do another test as soon as 7art 55mm1.4 to 1.4 comes
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it is quite possible that this effect is absent on the same Sony a7rii
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Dear, did you yourself understand that you have not written anything smart now? ) Go buy a better and brighter lens and repeat your experiment!
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When will there be a review for fresh mirrorless cameras?
For a long time they have been constantly flickering in articles, and there are no reviews.
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I have long dreamed of reading an objective review from Arkady on Fuji X-T3 / X-T4 / X-Pro3 :-)
Hopefully, the Fuji Mission will allow him to take a camera view.
There is even a form for applying for a test: https://fujifilm-x.com.ua/order
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There are already plenty of fresh mirrorless reviews, no worse than Arkady does.
The site of Radozhiv is so good that it makes reviews of old optics and cameras, as well as new little-known optics that cannot be found anywhere else. This is his niche, and to climb into the one where there are a lot of equally experienced competitors, IMHO, is useless.
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It is quite possible to combine, taking Fujik in the Fuji Representative office and winding Chinese or all sorts of helios on him.
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It is very difficult to make a detailed review of the cameras and personally it exhausting me greatly, from time to time I make brief impressions about this or that. For the last five years, I personally have not been interested in new bricks at all, they all look the same due to professional burnout on this basis.
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In fact, not only does the bokeh deteriorate, but also all sorts of artistic glare and flare disappears ...
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This problem is not reproduced on the Canon RP. I removed a light bulb at 1 \ 4000 - round bokeh with clear edges.
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Yes, I forgot to indicate, the hole was 1.8.
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Bokeh with “sharp edges”, sharp ie? Show the photo.
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I also noticed a difference between the mechanical and electronic first curtain when using an external flash in HSS mode at ultra-fast shutter speeds. With an electronic first curtain, the light from the flash comes with lines, and with a mechanical one everything is perfect. Check.
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