M9 - Slowest shutter speed problem...

[edmund]

Sorry, this may be a stupid question and likely answered in the M9 manual.

I have the camera in A mode. And I have set the slowest shutter speed to 1/125, and max ISO to 400.

However, when I am shooting, I can see that when it is metering it goes below 1/125 --- and shoots at any speed.

Am I forgetting to set something?

Thanks everyone -

 

[dannh]

Re: M9 - Max shutter speed problem...

I don't think it's possible to be in A mode and set the shutter speed, that's the point of A mode.

I think what you're referring to is the Auto-ISO feature. The way this feature works is that you can define the max ISO, and the lowest shutter speed to allow the camera to choose. What you have to keep in mind is that if you've hit the max ISO ceiling and your scene is metering dark, the camera will still go lower than your minimum specified shutter speed, to enable you to take a properly exposed shot.

 

[edmund]

Hey Dan - Thank you -- but I think I am still missing something.

I thought the whole point of the "slowest speed" setting under "Auto ISO setup" was to help prevent blur. So, let's say you have it set to 1/125 and AUTO ISO.

I thought the camera would then do whatever it could to make sure you didnt do slower than 1/125, therefore preventing blur, but perhaps compromising exposure in some instances.

 

[dannh]

From my experience, the feature is designed to try and achieve your minimum shutter speed, but give priority to always give you a proper exposure. If it's just too dark, the minimum shutter speed setting becomes kind of pointless. When you set a max ISO 400, that shutter speed is going to easily drop down below 1/125 in moderately dark settings.

In the end, it's a nice feature to have in some situations, but you've got to be reasonable about what to expect when there's not enough light.

- Dan

 

[atanabe]

Edmund,
The "A" selection on the shutter speed dial will adjust the shuuter speed from the max 1/4000 to the slowest speed based on the light and aperture. The Auto ISO setting has you set the lowest shuttter speed and the maximum ISO. What this does is to keep the shutter speed at or above the slowest shutter speed by increasing the ISO until the maximum ISO is reached then the shutter speed will slow down.

The settings that you put into the Auto ISO setting is very restrictive, 1/125 at a maximum of 400 ISO would be equivalent of shooting an interior lit by fluorescent lights at f2. With the shutter set to "A", if the light level dropped any lower and the aperture remained the same the only way for the camera to adapt is to lower the shutter speed below 1/125 and the speed will blink telling you that it is lower than what you set.

If the shutter speed was manually set and Auto ISO selected, the ISO will raise to the maximum ISO then the indicator will signal under exposure in the viewfinder.

 

[250swb]

I thought the camera would then do whatever it could to make sure you didnt do slower than 1/125, therefore preventing blur, but perhaps compromising exposure in some instances.

Does the exposure reading blink at you in the viewfinder? Its telling you your set parameters have been exceeded by the available light.

You are out at dusk for instance and the camera is in 'A' mode. If you set minimum shutter speed with Auto ISO the shutter speed will bottom out at say 1/125th at a certain light level, and from then on the ISO will start to go up depending on how dark its getting. When there is no more latitude available in the ISO (you reached 2500 or your upper limit has been reached) then the camera starts to flash at you and effectively says 'I'll maker an exposure anyway'. But its not going to compromise exposure, it will go below your set preference of shutter speed. If you want to compromise exposure when the available light is low set the camera to Manual and 1/125th and use Auto ISO, or set the ISO.

Steve

 

[edmund]

If you want to compromise exposure when the available light is low set the camera to Manual and 1/125th and use Auto ISO, or set the ISO.
Steve

Thanks everyone! -- this makes a lot more sense now.

For the things I am shooting usually, the exposure can be recovered in postprocessing. So it seems like the above tip might just do the trick.

Thank you all again!