Is this diffraction?
 

You would think after almost 400 posts I would have asked for advice on my footage by now...well here goes. These are some screen grabs from a recent gig. I'm not sure if this is the best way to get feedback? I will try to post footage tomorrow when I have more time. The client pointed out to me that the models faces were a little distorted at times. Did a quick search, and seems like the problem may be diffraction?? I think the footage is good, but not broadcast worthy.

(from left to right)
1st image: .mov, 2300kbps
2nd image: .mov, 6000kbps
3rd image: .mov, 2300kbps
4th image: .mov 600kbps

2nd and 4th images show the next frame after the others, in which the distortion is more apparent. I don't know if this should be happening?

My settings, to my knowledge, were as follows:
Panavision preset (or was it vividrgb, looks like panny right?)
f1.8
1/48
24f
+6db
standard def


JS

no - diffraction is caused by small apertures. Using f1.8 you won't get diffraction but you may get a shallow DoF which can also lead to soft focus, particularly when subject is darker than bg

yeah there wasn't much light there, but I thought it would be enough for the gig. So is the problem here a soft focus? I didn't bother focusing manually because all the models were not walking to the same location on the stage, and AF has worked great in the past. Sometimes I did have to do a quick manual focus though because I know it's difficult for the AF to function in lower lighting conditions.

was there a dirty sky light filter or something screwed on the end of the lens?

Ian
Festival Video and Audio Previews - Festival Previews Ltd

shooting at f1.8 in auto focus with a moving subject in front of a bright background you are almost certainly going to have problems with soft focus.

Also shooting at 24f in auto focus in any condition is not a good idea , adding the low lighting condition will make the auto focus a bigger problem.