Aperture goes wide open when camera just turned on, but read out is different, what's the problem?

[Domantas]

Before anything, I use Sony A7S III with samyang/rokiron f2.8 24 mm. I use manual or "movie" mode which is essentially also manual just for video.

So as I stated in the title, when I turn on my camera, aperture wildly goes wide open, which is not what is showed on the screen (whatever I have f4 or f11, it goes wide open no matter what was set before). It happens almost every time. It fixes when I adjust aperture by one stop. What is the problem? Please help I am really stressed, should I go to warranty or what? Maybe its something with settings? I was filming an awesome video and this happening almost all the time really annoyed me. Thank you!

 

[QuietOC]

Before anything, I use Sony A7S III with samyang/rokiron f2.8 24 mm. I use manual or "movie" mode which is essentially also manual just for video.

So as I stated in the title, when I turn on my camera, aperture wildly goes wide open, which is not what is showed on the screen (whatever I have f4 or f11, it goes wide open no matter what was set before). It happens almost every time. It fixes when I adjust aperture by one stop. What is the problem? Please help I am really stressed, should I go to warranty or what? Maybe its something with settings? I was filming an awesome video and this happening almost all the time really annoyed me. Thank you!

Check your "Aperture Drive in AF" setting. "Focus Priority" will cause the camera to open the lens aperture for better AF performance in low light. "Standard" should allow the aperture to stop down most of the time. AF-C can still require a larger aperture than what you have set. AF-C requires phase-detect which only works at larger apertures. Other camera settings also effect aperture behavior. There is probably a guide out there somewhere.

 

[Domantas]

But that seems to be a settings for still and mainly I do video

 

[Nokiron]

Do you have any actual native lenses besides your Samyang to test on?

Also, is the lens updated to the latest firmware?

 

[Erwann Loison]

But that seems to be a settings for still and mainly I do video

It's recommended to turn AF drive priority off for video, so you don't have that kind of problem or noise from the aperture opening/closing.

 

[Domantas]

Yes, both camera and lenses has latest firmware. I have only samyang right now

 

[Domantas]

But that seems to be a settings for still and mainly I do video

It's recommended to turn AF drive priority off for video, so you don't have that kind of problem or noise from the aperture opening/closing.

I afraid I didn't find such setting on Sony a7siii (at least in video mode). Menu is very different from sony A7SII I used before, that one had that.

 

[Erwann Loison]

But that seems to be a settings for still and mainly I do video

It's recommended to turn AF drive priority off for video, so you don't have that kind of problem or noise from the aperture opening/closing.

I afraid I didn't find such setting on Sony a7siii (at least in video mode). Menu is very different from sony A7SII I used before, that one had that.

On the a7RIV it's first tab, page 6, a7SII it's here: https://helpguide.sony.net/ilc/2010/v1/en/contents/TP0003227775.html?search=aperture drive in AF