NEX iso vs aperture choice (Tv-mode)
Knowing that in Shutter Priority, the camera has two options to maintain exposure value:
- Increase ISO
- Increase Aperture
Sony put changing ISO a priority over changing aperture. This is likely due to the fact that change in aperture changes characteristics of composition (DOF) whereas changing ISO doesn't. So, choosing larger aperture (and shallower DOF) is the last resort rather than first.
That being said, NEX-6 has auto ISO set to 3200. So, there is greater room than there would be in another that is limited to 1600 or 800. So, the threshold to use larger aperture would be reached sooner if the camera didn't have more ISO to play with.
Sony A55, Sony NEX-3, Sony F828