a6300 won’t go wide open in shutter priority

Started 4 months ago | Discussions thread
brilly Senior Member • Posts: 1,446
Re: a6300 won’t go wide open in shutter priority

sgkoala wrote:

brilly wrote:

sgkoala wrote:

brilly wrote:

Sympa wrote:

It may be unexpected that the aperture doesn't open all the way up before raising ISO, but it may make sense. The shutter speed is set, the camera selects the rest - that is what what 'S' mode means, right?

s mode doesn't mean 'dont open the aperture all the way' either

tbh i had never noticed this as have never felt the need to use shutter priority, M or P with auto iso take care of all i have needed

does seem silly though but id guess its for some sort of focus consideration like ensuring dof or accuracy

Maybe i’m not getting the issue here. If you are in S mode, you set shutter to 1/200th for example. The camera has to choose between f1.4 and ISO 400, or f2 and ISO 800, or f2.8 and ISO 1600, and so on.

Why do you think f1.4 and ISO 400 is the ‘right’ answer? What if at f1.4 the lens is not as sharp so the optimum IQ is at f2 and ISO 800? What if there are multiple subjects (eg two kids) and f1.4 is too shallow depth of field (one kid is out of focus) while f2.8 has both kids in focus?

If you definitely want to use f1.4 and 1/200th, then just flick the dial over to M and set f1.4 isn’t it easier?

because it opens up the aperture magically until f2 then stops

why did it ever change aperture? why not iso 1000000000 ? who says f2 is right?

With a constant SS and EV, there is a trade-off between aperture and ISO. I’m guessing the Sony engineers who wrote the logic felt that up to a certain point (f2), it’s probably better to open the aperture wider to keep the ISO low and reduce image noise. However, once the aperture has hit f2, the benefit of lower noise from a wider aperture is outweighed by the risk of too shallow depth of field or optical aberrations such as chromatic aberration or lower sharpness (which are much more a problem at f1.4 than at f2). Sony engineers estimated that most users would probably prefer the f2 image rather than the f1.4 image; and it’s not an issue because if the user wanted to specify both the aperture and shutter they would have either used M, or A with a minimum shutter set.

Can you or the OP give a real world scenario where the behaviour you mentioned is actually a problem and where either M or A with minimum shutter would not be an acceptable solution?

if you bothered to read my post i said it wasn't a problem - i just said it was odd behaviour

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