Sony A7 III Very Strange - Auto ISO

[Leethomas]

I tested my 50mm 1.8 lens - Low light It constantly shot it at 1.8 1/15/ sec.
I tested my 90mm 2.8 lens - Same Conditions. It constantly shot it at 2.8 1/100 sec.

Should this not be reversed? The Faster the lens -- the faster the speed ???

 

[Slug]

That's quite a variation. What ISO?

 

[Brownie]

What mode? Sounds like something is in auto?

 

[Leethomas]

Same Iso. Yes, in Auto.

 

[Brownie]

You're sure same ISO and the aperture held?

 

[Leethomas]

I'll try again Brownie. Maybe I was not "Apples" to "Apples"

 

[Slug]

Try a fixed ISO and run the same test.

 

[Brownie]

I could see the camera in auto trying to maintain a faster shutter speed for the 90 to ensure a sharp shot.

 

[iain clyne]

Is my memory twisted but isn't there a setting in auto ISO that keeps a fast enough shutter speed for the lens length in the menu for auto ISO. That's if auto ISO is being used.

 

[Leethomas]

The 'Auto Iso" was the problem. Thanks all.

 

[Brownie]

The 'Auto Iso" was the problem. Thanks all.

I sometimes run Auto ISO but only in M so I can choose the shutter and aperture and let the camera choose ISO. But, only up to a number I'm comfortable with, usually 6400 or 8000. Even at that I still find it creepy sometimes. Too set in my ways I guess.

Glad you got it sorted.