A tiny and personal test of some EVF

JeremieB wrote:

Roland Karlsson wrote:

C-Y-R wrote:

Pulse width modulation (PWM) is used to control the brightness of OLED panels of handphones

Does this mean that OLED EVFs on mirrorless use PWM as well?

Interesting question. I googled PWM flicker. OLEDS might be pulse width modulated for brightness at a frequency around 1 KHz. Some people claim they can see that, but most do not see it at all.

I have three comments

1. I have no idea if EVF uses PWM.
2. No, I do not think the problem with EVF is due to PWM flicker. I believe the problem is due to the fact that the camera cannot keep short enough exposure time.
3. I am not sure about PWM flicker sensibility. Is it for real?

Regarding number 2. It is quite easy to test. Just put the camera at M or Tv and set it a 1/100 second and there should be no problems. Then set it at 1/25 and there should be problems. I also guess that e.g. 1/30 and 1/25 should behave very differently. There should be temporal interferences. I do not have any modern EVF camera, so I have to go to a camera shop to look at this though.

Regarding number 3. I am a FPS gamer and know a lot regarding monitors and refresh rates and those problems. And I would be very surprised if anyone can see 1 KHz flicker. If you do a high speed movie of your 120 Hz monitor, then you will see that it flicker A LOT! It is only really on at less than 10% of the time or so. And, you cannot see it.

My understanding is that it's not the same thing as the refresh rate. It's alternance of normal and completely black image, at sufficient rate for the display to appear darker, because there is (was?) no way to dim it.

And to some extent under some frequency our iris adjusts to this, opens/close repeatedly and it could cause headaches to some person's, more if pwm rate is too low.

DXO measured it on some smartphones : https://www.dxomark.com/flicker-the-display-affliction/

For EVFs I didn't find any information. But EVFs being perfect probably there is no problem ( ).

It seems like most phones have considerable lower PWM rates than 1 KHz. Typically around 250 Hz. Then you start to get close to what might be visible for some. That is a questionable choice. That is probably for technical reasons. It is cheaper or it uses less battery.

Still, I am doubtful that this is the cause for EVF flicker. The EVF flicker seems to be worse in low light conditions.