[pschlute]

I think I've figured out what the "A" setting actually does with my K70.

With "A" setting the camera's brain adjusts BOTH aperture and shutter speed, turning K70 into a advanced point and shoot....letting me do the focusing.

It does a lot more than that.

It doesn't allow me to usefully change of aperture BECAUSE that's better done in post processing (Photoshop and NIK in my case).

You use aperture to (amongst other things) alter the depth of field in your image. That cannot be done in PP

[Lowell Goudge]

The lens when In the A position allows the body to control the aperture directly, as opposed to manually setting it with the aperture ring.

This permits the use of the following modes with auto exposure
-Av mode
-Tv mode
-Tav mode
- Program mode
In addition it allows the use of
- matrix metering,
-PTTL flash
-HSS Flash

I think I've figured out what the "A" setting actually does with my K70.

With "A" setting the camera's brain adjusts BOTH aperture and shutter speed, turning K70 into a advanced point and shoot....letting me do the focusing.

It doesn't allow me to usefully change of aperture BECAUSE that's better done in post processing (Photoshop and NIK in my case).

"A" lenses might not be very good photographing kids or birds or sports...but they're incredibly good at saving money.

see my post above, you are describing program mode only, the camera does a lot more with an A lens than you give it credit for

[UncleVanya]

I think I've figured out what the "A" setting actually does with my K70.

With "A" setting the camera's brain adjusts BOTH aperture and shutter speed, turning K70 into a advanced point and shoot....letting me do the focusing.

That’s not accurate - or perhaps more accurately, that’s only one option. In the Av mode on the camera dial, or the M mode, or the TAv mode you can certainly change aperture to whatever you want and in some of these modes the shutter speed or ISO or both will adjust to keep your exposure set as the camera thinks it should be. In SCN and P and AUTO (Green mode) things are more automated and you have limited control.

It doesn't allow me to usefully change of aperture BECAUSE that's better done in post processing (Photoshop and NIK in my case).

I’m very confused. Or rather you are confused perhaps. Aperture is a physical property of the lens. Post processing can’t change it. You can alter apparent depth of field making it shallower- but typically not deeper - using computational defocusing. You may be confounding aperture with exposure. In that case using M mode or using the exposure compensation features to bias the outcome plus post processing is the way to go.

Aperture can have a profound effect on the look of an image. Wide open it can give very clean subject Isolation if the lens is able to open wide enough for the subject distance and effect desired. Stopped down it can create a larger depth of focus.

"A" lenses might not be very good photographing kids or birds or sports...but they're incredibly good at saving money.

The A series Pentax lenses are manual focus only (although there are autofocus leaves with the A on the aperture ring) and plenty of shots of kids, birds and other sports have been made long before autofocus. The “hit rate” and speed of working will suffer, but zone focusing and stopped down aperture will bring more successes than you might think.