FORUMS: list search recent posts

smearing-shutter speed-shutter angle

COW Forums : Sony XDCAM - EX & Related

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
Michael O'Reilly
smearing-shutter speed-shutter angle
on Nov 23, 2008 at 5:07:06 pm

working with XDCAM 1080p24 and 1080p30. There is a "smearing" that occurs (motion blur) that I want to get rid of. I see it all the time in recent HD video so it seems to be a common problem. Changing the shutter speed does not get rid of it, so I thought maybe changing the shutter angle (which most video people would not touch having never encountered it before) would have some effect.

My experiments are limited to when I am out with a union crew - I do not have access to the camera until then.

I did a search for shutter angle but none of the posts actually addressed what changing the shutter angle would look like.

I am sure this has been posted before, but everyone is calling it something different - please forgive my noobie repeat question.

Thanks

Michael



Return to posts index

Don Greening
Re: smearing-shutter speed-shutter angle
on Nov 24, 2008 at 9:23:19 pm

[Michael O'Reilly] "Changing the shutter speed does not get rid of it, so I thought maybe changing the shutter angle (which most video people would not touch having never encountered it before) would have some effect. "

You're probably not going to like this answer but if you shoot 30 progressive frames a second you're going to get motion blur no matter how fast you set the shutter speed or how tight you have the shutter angle. There won't be a difference that I've been able to determine in using shutter angles instead of shutter speed. The main difference between the two is that you can set the shutter angle independent of frame rate, whereas with shutter speed you're restricted to a set of speeds depending on what your shooting mode is.

You can reduce the amount of motion blur in progressive modes by increasing shutter speeds but you won't eliminate it. As you increase shutter speed there will be less time for light to hit the imager for a given frame duration, so you'll end up with more of a stuttery look to the picture but with less motion blur. Think of a strobe light freezing the action of a fast moving object.

Progressive motion blur isn't necessarily a bad thing. It gives the perception of action provided it's done correctly and has achieved the look you're after by focusing the viewer's attention where you want it. If you look at any movie shot on film or 24p video you're going to see lots of motion blur when something passes in front of the lens with any kind of rapidity. Since it's impossible for the human eye to analyze each frame of film both in detail and in real time the viewer "gets it."

If you want to reduce motion blur as much as possible you need to shoot with a frame rate faster than 30p. You can increase the temporal resolution of the EX by shooting 60i, which is 60 interlaced frames per second or shoot 720p 60 (60 progressive frames per sec.).

- Don



Return to posts index

Michael O'Reilly
Re: smearing-shutter speed-shutter angle
on Nov 25, 2008 at 9:40:57 pm

Thanks for that thoughtful response Don. I've worked with Varicam footage at 720p24 and it exhibited none of the smearing artifacts I am seeing with this Sony (for the record, a PDWF350 with 1/2 inch chip).

My goal is to lose the hyper-real temporal plasticity of video. Believe it or not, but I cut my teeth on a Pixelvision toy camera that outputted 15fps. I learned from this toy that it is the temporal definition and not the spatial definition of the frame that makes video and film look so different.

So when shooting progressive was as easy as a menu choice, I jumped a the chance.

But this PDWF350 seems to be doing something different to the image than the Varicam (yeah, that's why Varicam's seem so sought after). We do have access to the next model up in terms of XDCAM cameras - I don't have the model number but it has a 2/3 inch chip - are there more temporal features/controls with the 2/3 inch chip XDCAM camera ?

thanks

Michael O'Reilly


Return to posts index


Don Greening
Re: smearing-shutter speed-shutter angle
on Nov 25, 2008 at 10:50:09 pm

[Michael O'Reilly] "We do have access to the next model up in terms of XDCAM cameras - I don't have the model number but it has a 2/3 inch chip - are there more temporal features/controls with the 2/3 inch chip XDCAM camera ? "

That would be the Sony PDW-700. Right now it's not classed as a CineAlta camera because it doesn't do 24p yet. Next year there will be a firmware package available to 700 owners that will enable 24p aquisition. I think the fundamental difference between the EX series cameras and the others such as VariCam, the other XDCAM HD cameras including the new 700 etc. is that the EX sensors are CMOS and the others use CCD's.

If you recall, a CCD sensor is scanned all at once whereas a CMOS sensor is not scanned instantly but instead from the top down. Therein may lie the difference with respect to increased motion blur with the EX, but since I've no shooting hours spent with cameras like the F355 or the VariCam my reasoning is just a supposition.

- Don



Return to posts index

Michael O'Reilly
Re: smearing-shutter speed-shutter angle
on Nov 25, 2008 at 10:57:56 pm

Interesting. Thanks for that post Don. That may very well be the difference with regard to the motion blur.

In reference to the firmware upgrade, will this also allow the user to use the 35Mbps setting instead of having to always use 50mbps ?

thanks

Michael


Return to posts index

Don Greening
Re: smearing-shutter speed-shutter angle
on Nov 26, 2008 at 4:55:47 am

It would seem that the only info available at the moment about the upcoming PDW-700 24p option can be found here:

http://pro.sony.com/bbsc/ssr/micro-xdcam/resource.promotions.bbsccms-assets...

It doesn't mention anything about 35 Mbits sec. recording but you never know what will be in the final firmware package. If I was to guess, I'd say no there won't be a 35 Mbit setting.

- Don


Return to posts index

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
© 2017 CreativeCOW.net All Rights Reserved
[TOP]