Blur in shutter priority (125)

I have been shooting Fashion Week of the Americas all week for this local mag (south beach miami fl) called Sidewalk magazine . . . and have been very happy with the results so far .. ive liked some of the designers . . julian chang one of my faves . . . and as the models get more comfortable some of their personalities are emerging . . making for some phenom shots . . .

I have been shooting each show in shutter priority mode (with my D60) and AF using a 550 EX for fill . . (given the quick paced nature of a runway show i feel automation is the only option so soul shooters no flames please )

in reviewing the images ive shot . . i have noticed on a handful of occaisions (out of 100's of pics) there has been an over exposure blur . . . not motion blur but the type you get when the shutter speeds are below the threshold for the given aperture for stopping motion . . (does that make sense? kinda like Av in low light) . . im certain that in the shots that have this the subject was going no faster than the other shots taken where the motion has been frozen (in some the subject is stationary) . .

my question is this: how can this happen with Tv set to 125 where for the most part it has sufficiently stopped the motion in all but a handful of instances?

No, not really.

Blur can be caused by camera shake, but you did not tell us what focal length you were using, or whether you used a tripod. The 550EX puts out a pretty short burst of light which tends to freeze the motion, but only if it is the dominant source of light. You stated that you were using the 550EX for fill. Blur can be caused by a slow shutter, but we don't know how fast the subjects were moving. Blur can be an out-of-focus blur caused by the subjects moving in or out of the depth of field, but we don't know what your aperture was or what the depth of field calculates to be.

You know, complete shot data can be important when you try to figure these problems out after the fact.

---Bob Gross---

A sample image of the problem photo helps a lot, too. You know what they say, a picture is worth a thousand words.

ok sure .. the stats:

focal length: varies but between 24-70mm
shutter speed: Tv 125
aperature: 4-4.5 (depending on focal length)

the subjects were stationary in alot of the unusable specimens in question . . camera shake may be responsible . . but fill flash or no . . shouldnt 125/100 s be fast enough to stop stationary motion? if the light was insufficient it would just come out under-exposed . . not blurred . .

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a couple more samples:

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I see some camera shake problem in one, and I see some subject motion blur in another one. Don't you see that?

---Bob Gross---

right you are . . and sure . . anyone can see it . . (i did mention it in a previous post) . . my question is that current settings should prevent that from happening and in almost every case other than a small handfull, it did . . . so why in these rare instances did it not . . . what went wrong?

anyway . . . i guess its just the ghost in the machine . . . and if not i'll figure it out eventually . . .