Spots on my Video at DVinfo.net

Gary Randall · July 17th, 2007, 03:52 PM

I did a wedding last weekend and during the reception there were 9-10 times where white or green spots were on the video. Mostly around the lights that were on the walls. Somtimes there were 3 to 4 of the spots in a line. I had a UV Filter over the lens. Could that have caused the spots? I was using a Sony VX2100. I hope this made since

Gary

Jim Sobolewski · July 17th, 2007, 05:08 PM

Can you post a screen shot of this problem.

John Cline · July 18th, 2007, 12:21 AM

I'm virtually certain what you are seeing is the point-source reflection of the lights as it bounces between the UV filter and the front of the lens. The points of light travel through the UV filter, which is flat, and reflect off the front of the camera lens, which is convex, then hits the inside of the UV filter and gets reflected back to the image sensor. There may be several of these bounces.

I was recently in Las Vegas shooting the Strip at night with my V1u. I had the UV filter mounted and immediately noticed exactly what you described. There are literally thousands of point source lights on the Strip, so this was a worst-case scenario. I removed the UV filter and the problem vanished. By the way, the V1u handled the lighting on the Strip exceptionally well and I came back with some great footage. There was detail in the shadows and the bright signs didn't get blown out. I was impressed.

John

Gary Randall · July 18th, 2007, 02:23 PM

Thanks John, I will take the filter off and see what happens

Gary

Tom Hardwick · August 27th, 2007, 10:22 AM

Yes, take that filter off. You've added two more dusty surfaces and at wide-angle you're shooting at a focal length of 6 mm, so all the dust is nearly within the D o F.

Remember that the PD/VX already have two elements in front of the zoom's front elements (the VAP OIS) so there's really no need for even *more* protection.

tom.

Jim Sobolewski · September 28th, 2007, 01:10 PM

Hmmm....I'm getting this same problem.4 or 5 mini lights around light bulbs or stage lights(looks like fire flies around the lights.)I get it with or without the uv filter.Any other cause for this?Or way to stop it?I'm using the vx2100 with the lens hood.Although i am shooting in auto maybe that has something to do with it.I am trying to learn full manual but i'm not there yet.

Tom Hardwick · September 29th, 2007, 05:30 AM

Jim, it's undoubetedly the VX's OIS steadyshot at work and nothing to do with the manual or auto exposure settings. Very easy to check from your armchair as you point the camera up into your ceiling light. Turn the OIS on and off and see the fireflies.

Now you have to weigh up the pros and cons of having OIS on your side. I'd guess that it's constantly helping you but only very infrequently hindering you.

tom.

July 17th, 2007, 03:52 PM	#1
Gary Randall Regular Crew Join Date: Sep 2004 Location: Hampton, VA Posts: 150	Spots on my Video I did a wedding last weekend and during the reception there were 9-10 times where white or green spots were on the video. Mostly around the lights that were on the walls. Somtimes there were 3 to 4 of the spots in a line. I had a UV Filter over the lens. Could that have caused the spots? I was using a Sony VX2100. I hope this made since Gary

July 17th, 2007, 05:08 PM	#2
Jim Sobolewski New Boot Join Date: Jun 2007 Location: Syracuse,NY Posts: 13	Can you post a screen shot of this problem.

July 18th, 2007, 12:21 AM	#3
John Cline Major Player Join Date: Oct 2002 Location: Albuquerque, New Mexico USA Posts: 333	I'm virtually certain what you are seeing is the point-source reflection of the lights as it bounces between the UV filter and the front of the lens. The points of light travel through the UV filter, which is flat, and reflect off the front of the camera lens, which is convex, then hits the inside of the UV filter and gets reflected back to the image sensor. There may be several of these bounces. I was recently in Las Vegas shooting the Strip at night with my V1u. I had the UV filter mounted and immediately noticed exactly what you described. There are literally thousands of point source lights on the Strip, so this was a worst-case scenario. I removed the UV filter and the problem vanished. By the way, the V1u handled the lighting on the Strip exceptionally well and I came back with some great footage. There was detail in the shadows and the bright signs didn't get blown out. I was impressed. John

July 18th, 2007, 02:23 PM	#4
Gary Randall Regular Crew Join Date: Sep 2004 Location: Hampton, VA Posts: 150	Thanks John, I will take the filter off and see what happens Gary

August 27th, 2007, 10:22 AM	#5
Tom Hardwick Inner Circle Join Date: Mar 2003 Location: Billericay, England UK Posts: 4,711	Yes, take that filter off. You've added two more dusty surfaces and at wide-angle you're shooting at a focal length of 6 mm, so all the dust is nearly within the D o F. Remember that the PD/VX already have two elements in front of the zoom's front elements (the VAP OIS) so there's really no need for even more protection. tom.

September 28th, 2007, 01:10 PM	#6
Jim Sobolewski New Boot Join Date: Jun 2007 Location: Syracuse,NY Posts: 13	Hmmm....I'm getting this same problem.4 or 5 mini lights around light bulbs or stage lights(looks like fire flies around the lights.)I get it with or without the uv filter.Any other cause for this?Or way to stop it?I'm using the vx2100 with the lens hood.Although i am shooting in auto maybe that has something to do with it.I am trying to learn full manual but i'm not there yet.

September 29th, 2007, 05:30 AM	#7
Tom Hardwick Inner Circle Join Date: Mar 2003 Location: Billericay, England UK Posts: 4,711	Jim, it's undoubetedly the VX's OIS steadyshot at work and nothing to do with the manual or auto exposure settings. Very easy to check from your armchair as you point the camera up into your ceiling light. Turn the OIS on and off and see the fireflies. Now you have to weigh up the pros and cons of having OIS on your side. I'd guess that it's constantly helping you but only very infrequently hindering you. tom.