PD 170 Question at DVinfo.net

Robert Bunker · May 26th, 2008, 06:51 AM

I'm new to videography and have a question about camera operation and settings.

My main interest is in shooting train movements. A couple of days ago I set up about 150 feet from trackside with the PD 170 on a tripod. The iris was set manually to 9.6 and focus was also on manual though gain remained in auto mode. Between the railroad right-of-way and my camera position was a highway that runs parallel to the tracks. That made my set up about 20 feet from the closest automobile traffic lane.

As I shot a train heading west with the camera stationary (meaning that I wasn't panning) and the lens set toward the telephoto side (I don't know how to express a zoom setting), some highway traffic passed my position east bound in the closest highway lane.

In looking at that footage afterward, I noticed that the image seemed to "contract" along the top of the frame whenever an automobile passed through the scene. That is, at the top center of the picture, the image was pulled down momentarily as the car passed and then returned to normal after it was beyond the frame.

I'm at a loss to understand what this is and how to correct for it but as I say I'm new to videography and still figuring things out.

Any explanation for this and how it might be remedied would be appreciated.

Tom Hardwick · May 26th, 2008, 12:41 PM

How are you watching this footage Robert - on an ageing CRT monitor? Does this distortioon appera on the camera's side screen on record and replay of the tape?

Always best to steer well clear of such small apertures such as f/9.5. F/4 is a lot sharper with such tiny chips.

tom.

Robert Bunker · May 26th, 2008, 12:59 PM

Tom,

You're absolutely right. It never occured to me to use the LDC screen for comparison but the LCD image shows no such tendency and the image on the computer screen in capture shows no such distortion, either.

I didn't think my monitor was that old (bought in June of 2005) but maybe it is.

Thanks for the suggestion.

May 26th, 2008, 06:51 AM	#1
Robert Bunker New Boot Join Date: Mar 2008 Location: St Paul, MN Posts: 12	PD 170 Question I'm new to videography and have a question about camera operation and settings. My main interest is in shooting train movements. A couple of days ago I set up about 150 feet from trackside with the PD 170 on a tripod. The iris was set manually to 9.6 and focus was also on manual though gain remained in auto mode. Between the railroad right-of-way and my camera position was a highway that runs parallel to the tracks. That made my set up about 20 feet from the closest automobile traffic lane. As I shot a train heading west with the camera stationary (meaning that I wasn't panning) and the lens set toward the telephoto side (I don't know how to express a zoom setting), some highway traffic passed my position east bound in the closest highway lane. In looking at that footage afterward, I noticed that the image seemed to "contract" along the top of the frame whenever an automobile passed through the scene. That is, at the top center of the picture, the image was pulled down momentarily as the car passed and then returned to normal after it was beyond the frame. I'm at a loss to understand what this is and how to correct for it but as I say I'm new to videography and still figuring things out. Any explanation for this and how it might be remedied would be appreciated.

May 26th, 2008, 12:41 PM	#2
Tom Hardwick Inner Circle Join Date: Mar 2003 Location: Billericay, England UK Posts: 4,711	How are you watching this footage Robert - on an ageing CRT monitor? Does this distortioon appera on the camera's side screen on record and replay of the tape? Always best to steer well clear of such small apertures such as f/9.5. F/4 is a lot sharper with such tiny chips. tom.

May 26th, 2008, 12:59 PM	#3
Robert Bunker New Boot Join Date: Mar 2008 Location: St Paul, MN Posts: 12	Tom, You're absolutely right. It never occured to me to use the LDC screen for comparison but the LCD image shows no such tendency and the image on the computer screen in capture shows no such distortion, either. I didn't think my monitor was that old (bought in June of 2005) but maybe it is. Thanks for the suggestion.