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Archive 2020 · "Sony’s ‘Shutter Speed Fine-Tuning’ Feature Totally Eliminates LED ...

  
 
LBJ2
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p.1 #1 · p.1 #1 · "Sony’s ‘Shutter Speed Fine-Tuning’ Feature Totally Eliminates LED Flicker"


"Sony’s ‘Shutter Speed Fine-Tuning’ Feature Totally Eliminates LED Flicker"

Somehow I missed this new feature on the A9II! Looks very promising!

"Last week’s Sony a9 II firmware update came with a couple of really useful features. Not only does it let you close the camera’s shutter when changing lenses, but the new ‘shutter speed fine-tuning’ feature is able to completely eliminate flicker from troublesome light sources.

As you can see in the demo video above, the new feature allows you to dial in shutter speeds like 1/843.2 or 1/1024.6 within a special “[Var. Shutter Set.] screen” before you start shooting. This “Hi frequency flicker” function allows you to reduce or entirely eliminate flickering from “artificial light sources (e.g. digital signage, electronic signboards, LED lights, etc.)” that appears when shooting with the electronic shutter."

https://petapixel.com/2020/04/13/sonys-shutter-speed-fine-tuning-feature-totally-eliminates-led-flicker/

https://www.youtube.com/watch?time_continue=30&v=t9szxjLuruw&feature=emb_logo



Apr 14, 2020 at 07:08 AM
derKoekje
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p.1 #2 · p.1 #2 · "Sony’s ‘Shutter Speed Fine-Tuning’ Feature Totally Eliminates LED Flicker"


Looks clunky, but useful in certain conditions. Also if different lightings exhibit flickering at different frame rates it’s not going to help much in a scene with crowded light sources, right?

I do like the closed shutter though. Here’s hoping that they bring that to the Mark IV models.



Apr 14, 2020 at 08:09 AM
LBJ2
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p.1 #3 · p.1 #3 · "Sony’s ‘Shutter Speed Fine-Tuning’ Feature Totally Eliminates LED Flicker"


I don't see it as clunky at all, at least what I saw in the video. If someone encounters the situation, they have a chance to dial in and then shoot away in silent mode. If not, then back to mechanical shutter. I don't have the A9II camera to test. Wonder if someone else has had the opportunity to try this out to see how practical/effective.

Conceptually, I like the approach very much and appreciate Sony addressing the situation. But also need to see how effective it is in reality.



Apr 14, 2020 at 08:15 AM
Jman13
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p.1 #4 · p.1 #4 · "Sony’s ‘Shutter Speed Fine-Tuning’ Feature Totally Eliminates LED Flicker"


derKoekje wrote:
Also if different lightings exhibit flickering at different frame rates it’s not going to help much in a scene with crowded light sources, right?


This generally won't be an issue, as it is unusual for different lights to be powered from wholly separate power sources, and the flicker is caused by the cycling of the AC power. You could end up in a situation where lights are powered from two separate circuits that are 120 degrees out of phase with each other (three phase power used in most commercial buildings is three hot legs that are each 120 degrees out of phase), which could add some complexity into finding the right speed, but because that phase angle is constant, even then you should be able to find a shutter speed that works for multiple circuits from the same power source.



Apr 14, 2020 at 08:27 AM
chiron
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p.1 #5 · p.1 #5 · "Sony’s ‘Shutter Speed Fine-Tuning’ Feature Totally Eliminates LED Flicker"


I assume it is also possible for the A9 to do this with a firmware upgrade. I wonder if Sony will do it?


Apr 14, 2020 at 08:54 AM
derKoekje
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p.1 #6 · p.1 #6 · "Sony’s ‘Shutter Speed Fine-Tuning’ Feature Totally Eliminates LED Flicker"


Jman13 wrote:
This generally won't be an issue, as it is unusual for different lights to be powered from wholly separate power sources, and the flicker is caused by the cycling of the AC power. You could end up in a situation where lights are powered from two separate circuits that are 120 degrees out of phase with each other (three phase power used in most commercial buildings is three hot legs that are each 120 degrees out of phase), which could add some complexity into finding the right speed, but because that phase angle is constant, even then you should be
...Show more

Nice. It’s good to get feedback from someone with more of an electrician background. That certainly makes it more useful. As long as it can be set up quickly enough it really puts the A9II on par with the the sports models. Now if they only added Log.



Apr 14, 2020 at 09:23 AM
osv2
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p.1 #7 · p.1 #7 · "Sony’s ‘Shutter Speed Fine-Tuning’ Feature Totally Eliminates LED Flicker"


sports dslrs automatically sense and change the timing of the shutter actuation to fight flicker, the a9ii does that in mechanical shutter mode as well... it's effective in many traditional lighting scenarios, but also very limited in what frequencies it can detect:

"Flicker at a frequency other than 100 Hz or 120 Hz cannot be detected." https://support.usa.canon.com/kb/index?page=content&id=ART168687&actp=LIST

this a9ii electronic shutter tweak changes the shutter speed, not the timing, so it's a different approach, probably better in terms of light sources that have radically different flicker frequencies, like dimmed led for instance.

https://www.davidsatz.com/aboutflicker_en.html




Apr 14, 2020 at 01:16 PM
PhotoTeacher
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p.1 #8 · p.1 #8 · "Sony’s ‘Shutter Speed Fine-Tuning’ Feature Totally Eliminates LED Flicker"


For indoor sports you need the fastest shutter speed possible at a reasonable ISO; I wonder if this feature will be really effective in these situations, or if the shutter speed that finally eliminates the flicker will be too slow?


Apr 14, 2020 at 01:54 PM
snapsy
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p.1 #9 · p.1 #9 · "Sony’s ‘Shutter Speed Fine-Tuning’ Feature Totally Eliminates LED Flicker"


osv2 wrote:
sports dslrs automatically sense and change the timing of the shutter actuation to fight flicker, the a9ii does that in mechanical shutter mode as well... it's effective in many traditional lighting scenarios, but also very limited in what frequencies it can detect:

"Flicker at a frequency other than 100 Hz or 120 Hz cannot be detected." https://support.usa.canon.com/kb/index?page=content&id=ART168687&actp=LIST

this a9ii electronic shutter tweak changes the shutter speed, not the timing, so it's a different approach, probably better in terms of light sources that have radically different flicker frequencies, like dimmed led for instance.

https://www.davidsatz.com/aboutflicker_en.html

The reason bands are visible in an electronic shutter exposure is due to the light cycling (bright->dark->bright) at different integral rates across the full-sensor readout. For example, if we examine Sony's A9II flicker-eliminating sample video we can observe approximately 12 visible bands of light in the LV feed at the initial shutter speed of 1/1024.6 (0.9759ms). Measuring a screen grab more closely in Photoshop I came up with about 11.6 bands. The A9/A9II's full-sensor readout rate is approximately 1/160 (6.25ms). If we see 11.6 visible bands this means the full-sensor readout captured 11.6 cycles of the light, so we can derive the frequency of the light illuminating the scene by dividing 1/160 (6.25ms) by 11.6, which gives us 1856Hz (0.5387ms per light cycle), probably PWM LED lighting. The bands disappear in the video when the shutter speed is changed to 1/843.2 (1.1859ms), which is approximately 21.51% slower than the initial shutter speed at the start of the video. That brings the exposure of each row to approximately 1/2 rate of the light's cycle (0.5387ms per light cycle * 2 = 1.0774ms, ie each row captures two full cycles of light, which will eliminate the gradations of light bands across all rows). My numbers don't precisely match up since the 1/160 readout rate is an approximation as is the number of bands counted. Based on the revised A9II manual's High Frequency Flicker Section, the new firmware gives the user very precise control over the shutter speed, which should allow the user to find one that's a near-even multiple of most lighting sources.



Apr 14, 2020 at 04:50 PM
osv2
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p.1 #10 · p.1 #10 · "Sony’s ‘Shutter Speed Fine-Tuning’ Feature Totally Eliminates LED Flicker"


nice bit of detective work.

that is 1856hz led flicker, alleviated by 1/843.2th shutter speed?

the a9 led banding in the dpr article, created by led advertising boards at field level, was calculated at ~7700Hz: https://www.dpreview.com/articles/7370859353/sony-a9-banding-reported-by-fro-fact-or-fiction

is there a shutter speed that is a near-even multiple of ~7700Hz, that is also quicker than the 1/800th minimum shutter speed that's required for shooting sports.

a relevant thread that you participated in, wrt led banding with mechanical shutters: https://www.dpreview.com/forums/thread/4348448



Apr 14, 2020 at 07:48 PM
snapsy
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p.1 #11 · p.1 #11 · "Sony’s ‘Shutter Speed Fine-Tuning’ Feature Totally Eliminates LED Flicker"


osv2 wrote:
nice bit of detective work.

that is 1856hz led flicker, alleviated by 1/843.2th shutter speed?

the a9 led banding in the dpr article, created by led advertising boards at field level, was calculated at ~7700Hz: https://www.dpreview.com/articles/7370859353/sony-a9-banding-reported-by-fro-fact-or-fiction

is there a shutter speed that is a near-even multiple of ~7700Hz, that is also quicker than the 1/800th minimum shutter speed that's required for shooting sports.

a relevant thread that you participated in, wrt led banding with mechanical shutters: https://www.dpreview.com/forums/thread/4348448


1/3850, 1/2566, 1/1925, etc... should work.



Apr 14, 2020 at 09:10 PM
elimoss
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p.1 #12 · p.1 #12 · "Sony’s ‘Shutter Speed Fine-Tuning’ Feature Totally Eliminates LED Flicker"


Unlike phase cut dimmers, LED PWM controllers can drive any speed and duty cycle as you turn the knob, so to speak. Moreover, it is easy to program them to change the frequency dynamically in response to an ambient light sensor (or scene luminance, if you have a sign), just like a phone screen.

So there isn't going to be a universal solution, but this is surely helpful.



Apr 14, 2020 at 09:56 PM





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