Strange ghosting issue...camera issue? at DVinfo.net

Mat Thompson · September 20th, 2007, 03:34 PM

Hi guys

A friend of mine hired an XL1s and shot some quick bird fly bys (1/250th sec - interlaced).

His footage is showing extreme ghosting which you can see in the footage when its played (see attached). I know this wouldn't happen on my XL2 with these settings and my feeling is there could have been some issue with the camera.

Can anyone think of any reason this might occur ?

Cheers
Mat

Edward Carlson · September 20th, 2007, 04:41 PM

I believe that's just iMovie trying to show the interlaced image. Go into the preferences > Playback. One of the options is Highest (field blending.) Change that to High (better image) and see how it looks.

Mat Thompson · September 20th, 2007, 05:24 PM

Thanks for your post but this does show up in the footage itself so I don't think its down to interlacing. Its pretty extreme and doesnt look like interlace to me...however I'm no expert hence the post.

I will get him to look at that though!

Don Palomaki · September 21st, 2007, 04:53 AM

The interlace explanation makes sense to me.

Does it only appear on moving objects?
How fast was the object moving?
Can you do a single field grab, not a frame grab?
If it is interlace, a single field should show none of this ghosting.

With a very fast moving object, interlace artifact in a frame grab will not look like the jagged vertical edge we often associate with it, but like two separate objects with reduced contrast in the image, with possibly some overlap at normal contrast.

Based on the image, I would estimate that the bird was moving across the camera field of view at very roughly 30 feet per second.

Mat Thompson · September 24th, 2007, 07:46 AM

Thanks for your post and info Don....I will have a chat to my friend.

September 20th, 2007, 03:34 PM	#1
Mat Thompson Trustee Join Date: Sep 2006 Location: Kent UK Posts: 1,397	Strange ghosting issue...camera issue? Hi guys A friend of mine hired an XL1s and shot some quick bird fly bys (1/250th sec - interlaced). His footage is showing extreme ghosting which you can see in the footage when its played (see attached). I know this wouldn't happen on my XL2 with these settings and my feeling is there could have been some issue with the camera. Can anyone think of any reason this might occur ? Cheers Mat Attached Thumbnails

September 21st, 2007, 04:53 AM	#4
Don Palomaki Wrangler Join Date: Sep 2001 Location: Northern VA Posts: 4,488	The interlace explanation makes sense to me. Does it only appear on moving objects? How fast was the object moving? Can you do a single field grab, not a frame grab? If it is interlace, a single field should show none of this ghosting. With a very fast moving object, interlace artifact in a frame grab will not look like the jagged vertical edge we often associate with it, but like two separate objects with reduced contrast in the image, with possibly some overlap at normal contrast. Based on the image, I would estimate that the bird was moving across the camera field of view at very roughly 30 feet per second. __________________ dpalomaki@dspalomaki.com

September 20th, 2007, 04:41 PM	#2
Edward Carlson Major Player Join Date: Mar 2007 Location: North Hollywood, CA, United States Posts: 807	I believe that's just iMovie trying to show the interlaced image. Go into the preferences > Playback. One of the options is Highest (field blending.) Change that to High (better image) and see how it looks.

September 20th, 2007, 05:24 PM	#3
Mat Thompson Trustee Join Date: Sep 2006 Location: Kent UK Posts: 1,397	Thanks for your post but this does show up in the footage itself so I don't think its down to interlacing. Its pretty extreme and doesnt look like interlace to me...however I'm no expert hence the post. I will get him to look at that though!

September 24th, 2007, 07:46 AM	#5
Mat Thompson Trustee Join Date: Sep 2006 Location: Kent UK Posts: 1,397	Thanks for your post and info Don....I will have a chat to my friend.