How long are "Blaster Bolts"?

From a standard Stormtrooper gun, or a hand weapon like Han Solo's or Jango Fett's? Is the average blaster shot longer than a lightsaber? Is it three feet long? Eight feet long? Or is the actual "shot" bullet-sized, glowing white hot, and we are simply seeing an after image streak, burned across our cinematic retinas, like the blur of tracer shots?

 

Couldn't a screen-cap of some of the fighting scenes in the movies answer this question?
[image=http://images4.wikia.nocookie.net/__cb20091202153106/starwars/images/thumb/d/d9/JangoFlying-AotC.jpg/231px-JangoFlying-AotC.jpg]

Looks about the same length as a lightsaber blade to me.

 

I bet it depends on a power setting or the type of blaster. I'm pretty sure there are short blasts and longer ones in the movies. (Lightsabers aren't all the same length because Yoda's is definitely shorter than others.) ...On another note, you know how in ANH, the stormtroopers are told to load their weapons? Well I wonder what they were loading them with? Bolts?

 

All blasters have power packs, so the stormtrooper squad leader was telling his troops to put in fresh power packs.

 

Well in the EU it was explained that the colors you see being shot are tracers- scientifically speaking, the properties of a blaster bolt would technically make it invisible, so the authors of the EU decided that tracers are what you see- so any pictures or anything wouldn't really tell you the length, would they? Actual blaster bolts could be shorter or longer than the tracers.
Also, it would be hard to judge unless one were to know the exact speed of the blaster shot...