Ray, if you are still following this thread and you have a minute, could you explain further how you are using the Nikon Auto-ISO with its Av mode? I'm curious how this differs from my Pentax's TAv mode ... and what advantages you are getting from your way of going at it.
Sure. With TaV mode (or any other name for setting aperture and shutter speed manually while letting ISO adjust automatically), you set two variables and let the third float. BUT, you still have to keep an eye on that third variable and adjust one of the other two when the third gets too close to the end of it's range. In TaV, you generally keep an eye on shutter speed and adjust it when ISO gets too high or low. This can be an issue when there's too MUCH light or too LITTLE light. It's really not much different than shooting in Aperture priority mode with manual ISO - there you have to keep an eye on the shutter speed and adjust the ISO when the shutter speed is getting too slow, or in the case of very bright light, faster than the camera's maximum. There's still a lot of monitoring and adjusting going on in bright or low light, and particularly as you move between changing light situations.
The way the Coolpix A works (as well as a few other cameras by Nikon and other manufacturers) is that you use Aperture Priority mode and auto-ISO. Within the auto-ISO menu, you can establish your base ISO, a maximum ISO, and a minimum shutter speed. You set the aperture manually and then the camera will stay at the lowest ISO it can while still maintaining the minimum shutter speed you've designated. If there's an abundance of light, the ISO will stay at it's base setting and shutter speed will automatically go as high as needed to maintain a proper exposure. In TaV mode, you'd have to keep an eye on the meter and raise the shutter speed manually in this situation.
As light decreases below where the camera can maintain both the minimum shutter speed and base ISO, it will automatically raise the ISO, but only as much as necessary to maintain your minimum shutter speed. It will continue like this until the camera hits the maximum ISO you've designated. Only if there's so little light that the camera can't maintain your minimum shutter speed at the maximum ISO you've designated will the camera then violate the minimum shutter speed and reduce the speed by exactly as much as needed to get a proper exposure. You don't have to do anything but recognize that in very low light, you may end up at a slower than optimal shutter speed and adapt your shooting to that situation.
This is the exact same sequence of adjustments I'd make if I was setting things manually or if I was using TaV, or Av with manual ISO. But I don't have to think about each incremental step - I only need to be aware of it at the extremes. As I move between light and shadows and even extreme shadows, all I need to do is work the exposure compensation control and the camera will handle the rest until it gets darker than my settings will support and then I have to check to see if the shutter speed is coming down below my minimum.
With I'm using the Coolpix A for street shooting, I set the camera for a maximum ISO of 6400 with a minimum shutter speed of 1/500. I'm often shooting moving subjects while I myself am moving. I find that I need to maintain a shutter speed of 1/500 whenever possible to get the highest percentage of shots not affected by either subject movement or camera shake (or a combination of the two). I shoot using zone focus (which is what Ricoh's "snap focus" is essentially a very convenient shortcut for), so I'm trying for a lot of depth of field, which requires a relatively small aperture - usually f7 or f8 when possible. When I'm out shooting on a bright day with deep shadows (a pretty common occurrence), the camera will automatically bump the shutter speed up well above 1/500 when bright conditions require it, and will crank the ISO up well above the camera's base ISO to maintain that 1/500 setting when I hit some fairly deep shadows. I don't have to think about that - I just have to read the light and adjust the exposure comp to bias the exposure when needed. With TaV mode, I'd frequently have to adjust the shutter speed either in very bright or very dark situations. If I'm staying in really consistent light, that's not usually much of a hassle, but I'm usually in changing light one way or another and the camera handles it on the Nikon, freeing me up to just try to nail the moment. Only when I move into really low light, by moving indoors or shooting at night, do I have to change this basic setting. Then I'll usually open up the aperture to f3.5 or even 2.8 and just stay aware that my "zone" of focus, my depth of field, is much narrower than when I'm shooting in good light. And I have to be aware that my shutter speed may also come down a bit as well, even with those brighter apertures. But I don't have to worry about setting that - just taking note of it and adapting to it.
The GR does have this same basic feature and uses this same type of logic - the only problem for me is that it doesn't let you set the minimum shutter speed any faster than 1/250. That's fast enough for a lot of people and it's fast enough for me for some types of shooting, but it's not fast enough for me when I'm shooting on the street. The Nikon goes up to 1/1000, faster than I'd need with for anything with a 28mm focal length, but there's no harm in offering it. On their DSLRs, they allow pretty much the full range of the camera's shutter speeds and they offer an auto setting for the minimum shutter speed to deal with zoom lenses - it adjusts the minimum based on the focal length. It uses the 1/focal length convention as a default and then you can bias it up or down by one or two full stops to account for shooting action at the fast end, or maybe to using a stabilized lens for a static subject at the slow end. Samsung uses pretty much the same system with it's APS mirrorless bodies. And Fuji has raised it's minimum shutter speed to 1/500, which is enough for me with most of their great wider prime lenses, but it's still a silly restraint given that they do have longer lenses that someone may try shooting action with and where 1/500 may still not be fast enough for those uses. Some other makers, like Sony, Panasonic, Olympus, and others, don't allow for ANY sort of shutter speed control in Av mode with auto-ISO, so Ricoh is ahead of many - they just don't take it as far as I need them to for how I shoot on the street.
