Shutter speed decreases in live view?

Hi, I'm using a DSLR (Nikon D5100, to be precise).

Suppose I set the shutter speed to 1/30, when i shoot using the optical viewfinder everything turns out fine.

But when I shoot the exact same picture ( same light, aperture, zoom, angle etc.) in Live View, it changes.

Manual Mode:
Optical Viewfinder: Shoots fine at 1/30.
Live View: The shutter speed still SAYS 1/30 but it visibly takes much longer. Hence, if my hands shake a little the picture is blurred. But if they don't shake, the picture turns out the same.

Auto Mode:
Optical Viewfinder: Shoots fine at 1/30
Live View: As soon as i switch to live view, the camera changes the shutter speed to 1/8 (or whatever it wants).

Basically, it seems that the camera needs to make the shutter speed longer in Live View for the picture to turn out the same way it would have when using the viewfinder.

Why does this happen?

Also, if your name is "Hondo", please refrain from commenting.

Because of the way that Nikon and Canon implemented live view, there will always be a delay between shutter press and actual exposure. The shutter speed will operate as set, but there's a distinct and frustrating delay to get there.

For live view, you camera is using the main sensor, with the shutter open and the mirror raised. When you press the shutter release, the shutter and mirror have to be reset back to starting position, and sensor data cleared. Then the camera can actually take the shot.

And there's nothing at all you can do to change the way it works. If you want to use live view, then you have to learn to live with the delay.

Sony and Olympus DSLR's use a secondary sensor to drive the live view system, and don't have this issue.

Live view does take longer to focus so that may explain a delay in taking a photo. In manual mode, if you set 1/30 it should take the photo at 1/30.

What are you taking a photo of? And what metering mode are you using? In auto you may be looking at a slightly different place, hence the difference in shutter speed. Is the camera on a tripod?

In any mode, the click takes longer because LlveView has to be turned off first before the picture can be taken. In LiveView, the mirror is raised and the shutter opened to allow the digital sensor to transmit images to the LCD like a closed circuit TV. LiveView is turned off by closing the shutter, lowering the mirror then erasing the cache memory contents. That takes an (audibly) noticeable amount of time.

Ideally there should be no change in shutter speed, whether it's LiveView or not but any explanation will be more accurate if you mentioned aperture value change too. I highly suspect there was.

If shutter speed went from 1/30s to 1/8s which is two whole stops longer, aperture size should go two whole stops smaller to maintain a correct exposure value. In Auto mode when using the optical viewfinder, shutter speed may be the one determined first but when LiveView is on and the shutter is opened, aperture size might be the one set first. It all depends on how the camera was programmed to compute for the values.

There may be a difference in priorities but rest assured the exposure value remains the same. There will be noticeable differences in DOF and amount of blur in certain situations though that is why the dSLR is best used in manual mode using the optical viewfinder for absolute total control of everything.