[goso]

At a wedding last weekend at an old Tudor inn can anybody explain the ghostly mist ?

[Bursar]

Sounds like one for Yvette Fielding and the Most Haunted crew!

[grantsteve]

Looks like a bit of movement mid exposure to me. The lady on the left of shot also appears to have moved during the exposure.

[matt_p]

Looks like the little kid in pink is chucking a piece of material about mid exposure.

[Brammers]

Motion blur! That's 1/3 of a second, as you can see the shot is very unsharp throughout. With good technique and a form of image stabilisation (a tripod counts as image stabilisation!) you'd have got the non-moving subjects sharp.

The fast moving subjects (such as the weird 'mist') are blurred due to the camera capturing all of their movement over 1/3 of a second.

Next time increase your ISO - yours was on 100 which is very low for shooting indoors.