Scanning Lines in some shots

[Jason Bowers]

Hi Guys,
The problem that i'm having is that in certain shots it seems that the scanning lines are visible in the final render. I am using a pd-170 and a vx2100 with premiere pro 1.5. Is it possible that the vx2100 shows the upper field first and the pd-170 shows the lower field first. Anyone have this happen. No clients seem to notice but I notice right away. Also i am viewing it on a 51" big screen as well.

Thanks
Jason

[Tommy James]

The reason why you are seeing scan lines is because you are shooting with a standard definition interlace camera and you are blowing up your video to 51 inches. To properly shoot for the big screen you need a progressive scan camera. I use a JVC JY-HD10 camera that is fully progressive at 720 scan lines.

[Jason Bowers]

The scan lines are only visible on certain shots. Not all shots have the lines. They are also in slow motion as well. Might this be the problem?

[Peter Jefferson]

looks like a resampling/rendering issue within premier.. r u using any hardware? RTx100?? Storm?

it could be a number of things...
need more info..
what KIND of shits does it show up in?? Shits with Detailed fine lines?? flat colours? certain colours... is it onnly the one camera which this is visible from??

need more info bro

[Tom Tomkowiak]

I think Peter meant to write 'shots'

[Boyd Ostroff]

What shutter speed are you shooting at? If you used auto and don't know then turn on "data code" during playback and it will be displayed. If it's less than 1/60 sec (NTSC - or 1/50 PAL) then this could be an issue. Speeds slower than this are accomplished by field doubling which will cut your vertical resolution in half.

[Tommy James]

Your 51 inch big screen television may be a DLP or LCD projector. If so these big screen televisions are natively progressive display devices and interlaced footage may look terrible unless the footage is deinterlaced.

[Boyd Ostroff]

That *might* be an issue but I sort of doubt it. Then again, I don't know what your expectations are for a large screen. But really, I don't consider anything measured in inches to be "large" myself ;-)

Seriously, I shot a lot of footage on my Sony PDX-10 which has much smaller chips than a PD-170 and is also interlaced scan. We projected it on a 44 foot wide screen with a 10,000 lumen Barco DLP projector in an opera. You really could not see any scan lines. The image appeared a little soft (like it was out of focus) if you were close to the screen, but that is just the unavoidable consequence of only having 720x480 pixels to work with.

I also shot footage with my Z1 in PAL DV mode (720x576) and projected on a 48' screen with a Sanyo 10,000 lumen LCD projector for another show. Didn't see any scan lines there either.

I suspect something else is going on if you see "lines"....

[Jason Bowers]

http://s65.yousendit.com/d.aspx?id=0...635YSI9CCMIB2F
Sorry guys here is a link to a picture showing what I mean. Any suggestions would be great. This was shot with the vx-2100

[Tommy James]

I have downloaded the footage and what you are seeing is interlace artifacts typical of what happens when you display interlaced footage on a progressive monitor. What a progressive monitor does is combine the two fields into one image and since there are temporal displacements between the 2 images the fields do not line up and you see the scan lines. What you need to do is to deinterlace the footage with a deinterlacing software program. Some televisions have deinterlacers built in so you do not always see interlace artifacts. You might also want to consider buying a camera that is capable of shooting progressive footage or has a progressive like shooting mode. The camera that you own works fine for the big CRT projectors that are natively interlace display devices. However for the new big screen televisions such as the DLP and LCD projectors there are better camera choices because these televisions are natively progressive.

[Jason Bowers]

Hi Tommy,
This image was taken directly from my timeline in premiere pro it is not for the big screen so I don't think that is the problem. The lines show up on a 20" crt as well as my 19" crt monitor. Also it only shows up sparodically. Could it be the tape? I have only used sony tapes in my sony cameras.

[Boyd Ostroff]

Those look like ordinary interlace artifacts to me. They would be caused by movement, either the camera or the object. Pretty much the nature of interlaced video. See the following: http://www.100fps.com/

BTW, you never answered my question about the shutter speed.

[Jason Bowers]

Boyd,
I can't seem to find that tape to check the shutter speed, I looked at some other shots though and they are either at 90 or 60. How can I get away from these in my shots.

[Boyd Ostroff]

Shoot at 1/60 for best results. Use a tripod. Other than that, not much you can do when things move in interlaced video. First the camera captures scan lines 1, 3, 5, 7, 9, etc and then 1/60 sec later it captures lines 2, 4, 6, 8, 10, etc. When something moves its position will be different on every other line. That produces the comb type effect that you see.

You could try deinterlacing with a "smart" program. One multiplatform choice is DVFilm Maker - try their free demo:

http://www.dvfilm.com/maker/

But do you notice this effect as you watch the video in motion on a monitor, or just in the stills? Beyond that, remember there are only 480 scan lines available in NTSC video. There will always be some stair-stepping noticeable on hard edges; it will be more pronounced as they approach horizontal orientation.

[Jason Bowers]

Hi Boyd,
Sorry about the cross post my mistake. I was wondering if you can move this post to the camera forum and see what they have to say. Your response seems right but I don't understand why it only happens on some shots and not all moving shots.

Thanks

Jason