Enlightenment please?

I'm using auto ISO in Manual for BBF. I have set my minimum and maximum sensitivity and minimum shutter speed to Auto. I set Auto for the shutter speed without really understanding why. Can someone please explain exactly what setting Auto for shutter speed in this context actually does and why it's a good/bad idea?

It is a great idea. IT keeps you from using a to slow shutter speed for the lens you are using. It even looks at your zoom lens and sets it accordingly to the zoom you are using at the time of the shot.

In manual mode it probably won't d as much good but it won't hurt either. The Auto ISO part though will compensate for any light changes you will get. Sometimes you will need to use exposure compensation though to adjust for the scene since the Auto ISO will tend to override your Manual settings.

canuck257 said:

I'm using auto ISO in Manual for BBF. I have set my minimum and maximum sensitivity and minimum shutter speed to Auto. I set Auto for the shutter speed without really understanding why. Can someone please explain exactly what setting Auto for shutter speed in this context actually does and why it's a good/bad idea?

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The shutter speed slider under in the Auto-ISO menu allows you to set shutter speed parameters that work in conjunction with the Auto-ISO function instead of a single, predetermined shutter speed. Think of it as a "teamwork" sort of approach that gives you some flexibility: Auto-ISO tries to keep your ISO at the lowest possible level to keep noise under control, but does so in conjunction with shutter speed setting you've selected. The slider allows you to set rough guidelines for the sort of shutter speeds you find acceptable (Slower or Faster). If the slider is left in the center, the function will use shutter speeds that equal or exceed the focal length of the attached lens.

Specifically, the Auto ISO "Minimum Shutter Speed" is the threshold when Auto ISO kicks in and starts increasing. Normally in usual practice, as the light becomes more dim, the shutter speed falls. But when it hits this threshold, then then it holds there, and Auto ISO starts increasing instead. When ISO hits Maximum, then shutter speed has to continue its fall.

What that means is that any active Auto ISO picture (when ISO is moving, between Minimum and Maximum) will use that Minimum shutter speed. Auto ISO will increase, but this shutter speed will be held, as long as possible. So this shutter speed has importance, it is what will be used.

Auto ISO does not really try to stay low, instead when active, it simply does what it must do to try to hold the proper exposure. I suppose it does try not to overexpose. But Auto ISO is always a last resort, only active when at a hardware limit and all else fails. The real hardware limit is the 30 second shutter speed, but that is hopelessly impossible to handhold, so they added this new shutter speed choice to use as a limit. Auto ISO does try to hold this minimum shutter speed as long as it can. Give it some thought, it is what will be used (if Auto iSO is active).

What Auto does there (as shutter speed) is to set this minimum shutter speed threshold to be the standard 1/focal length shutter speed for FX, for example like 1/50 second for a 50mm lens. Or 1/(focal length * 1.5 crop factor) for DX cameras... for the current lens zoom in use. Considered a minimum that most people might be able to handhold steady if they try hard, but it is just a guideline, not an absolute. We might have other opinions.

Horoscope Fish said:

The shutter speed slider under in the Auto-ISO menu allows you to set shutter speed parameters that work in conjunction with the Auto-ISO function instead of a single, predetermined shutter speed. Think of it as a "teamwork" sort of approach that gives you some flexibility: Auto-ISO tries to keep your ISO at the lowest possible level to keep noise under control, but does so in conjunction with shutter speed setting you've selected. The slider allows you to set rough guidelines for the sort of shutter speeds you find acceptable (Slower or Faster). If the slider is left in the center, the function will use shutter speeds that equal or exceed the focal length of the attached lens.

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I don't think this option is available for the D7100. Is it on the D7200? or is it a D750 option? Just asking, because I think it is a nice option that would be nice for me, but the OP only has a 7100 & 7200 listed as camera. Maybe I am just missing it. I have been know to do that in the past. Ha!

cwgrizz said:

I don't think this option is available for the D7100.

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Yes, the D7100 does have this option.

Go to Auto-ISO -> Minimum Shutter Speed -> Auto and then click right one more time to get to the slider. That's how I remember it, anyway.

The Auto ISO shutter speed "Auto" is a new feature, in the newer models. The D7100 and D7200 and D750 have it, but the D7000 does not.

It is described in the Auto ISO section of the manual. Under 3: Adjust Settings there.

Thanks [MENTION=13090]Horoscope Fish[/MENTION] and @WayneF. I had looked for the option before a week or so ago when I saw it mentioned, but couldn't find it even though I thought I had seen it before on the D7100. I looked again before I posted, but did not have Auto (shutter) selected. I had shutter minimum to 100. Duh! I told you I could miss it. Ha! Again Thanks.