Does using the digital doubler.... at DVinfo.net

Mark Moreve · October 5th, 2010, 01:04 PM

Hello
Can somebody tell me when using the xf305 does using the digital doubler reduce the resolution of the camera & if so what to. If not is it a good way of crushing the depth of field more. Do you loose two stops of light like on a 2/3 inch doubler?
Thanks
Mark

Doug Jensen · October 5th, 2010, 01:52 PM

The camera is just magnifying the pixels. The digital extender has nothing to do with optics, so therefore, it does not cause any loss of light or change the depth-of-field. Not only that, you can do exactly the same thing in post and it will look the same.

For example, if you have FCP:
1) Put a clip on the timeline.
2) Double-click on the clip and go to the Motion Tab.
3) Change the Scale to 150%.

Now you've just done exactly what the camera's digital extender would have done. But, by waiting until you got to post, you still have the option of changing your mind and not scaling it, moving the positioning around to change the composition, or scaling less than 150% if that would be more than you need.

The only time I'd ever use the digital extender if I was doing a live shot of breaking news or something where post was not an option.

Peter Moretti · October 6th, 2010, 02:54 AM

Doug,

I can see no appreciable difference between using the digital convert or resizing in post.

But I think there should be a difference, esp. when images have a lot of detail. This is because using the digi-tele does the upsizing before compression. While resizing done in post is done after compression.

Now maybe I'm missing something, or maybe the XF codec is so good that it really doesn't matter. But I do think there should be a difference.

Doug Jensen · October 6th, 2010, 05:09 AM

Peter,

I thought the exact same things you are thinking before I did my testing. But in the real world, I can see no appreciable difference in the final video.

Mark Moreve · October 6th, 2010, 03:07 PM

Thanks Doug, what a shame I thought it may be a great way of crushing the DoF. never mind.
Regards
Mark

Mike Sertic · October 7th, 2010, 10:46 PM

Has anyone looked at how the digital extender functions in the 720p formats? Does it just window the center 1280x720 portion of the sensor and record that? The fact that it is a 1.5 extender suggests that might be the case, which could probably deliver pretty respectable quality on par with the regular 720p modes.

October 5th, 2010, 01:04 PM	#1
Mark Moreve Regular Crew Join Date: Jan 2009 Location: london Posts: 125	Does using the digital doubler.... Hello Can somebody tell me when using the xf305 does using the digital doubler reduce the resolution of the camera & if so what to. If not is it a good way of crushing the depth of field more. Do you loose two stops of light like on a 2/3 inch doubler? Thanks Mark

October 5th, 2010, 01:52 PM	#2
Doug Jensen Vortex Media Join Date: Jan 2009 Location: Florida Posts: 3,417	The camera is just magnifying the pixels. The digital extender has nothing to do with optics, so therefore, it does not cause any loss of light or change the depth-of-field. Not only that, you can do exactly the same thing in post and it will look the same. For example, if you have FCP: 1) Put a clip on the timeline. 2) Double-click on the clip and go to the Motion Tab. 3) Change the Scale to 150%. Now you've just done exactly what the camera's digital extender would have done. But, by waiting until you got to post, you still have the option of changing your mind and not scaling it, moving the positioning around to change the composition, or scaling less than 150% if that would be more than you need. The only time I'd ever use the digital extender if I was doing a live shot of breaking news or something where post was not an option. Canon XF305 Digital Tele-converter on Vimeo __________________ Vortex Media http://www.vortexmedia.com/ Sony FS7, F55, and XDCAM training videos, field guides, and other production tools

October 6th, 2010, 02:54 AM	#3
Peter Moretti Trustee Join Date: Mar 2007 Location: Sherman Oaks, CA Posts: 1,259	Doug, I can see no appreciable difference between using the digital convert or resizing in post. But I think there should be a difference, esp. when images have a lot of detail. This is because using the digi-tele does the upsizing before compression. While resizing done in post is done after compression. Now maybe I'm missing something, or maybe the XF codec is so good that it really doesn't matter. But I do think there should be a difference. __________________ Avid Media Composer 3.1.3. Boris Red and Continuum Complete. Vegas 8.0c. TMPGEnc Xpress Pro 4.0

October 6th, 2010, 05:09 AM	#4
Doug Jensen Vortex Media Join Date: Jan 2009 Location: Florida Posts: 3,417	Peter, I thought the exact same things you are thinking before I did my testing. But in the real world, I can see no appreciable difference in the final video. __________________ Vortex Media http://www.vortexmedia.com/ Sony FS7, F55, and XDCAM training videos, field guides, and other production tools

October 6th, 2010, 03:07 PM	#5
Mark Moreve Regular Crew Join Date: Jan 2009 Location: london Posts: 125	Thanks Doug, what a shame I thought it may be a great way of crushing the DoF. never mind. Regards Mark

October 7th, 2010, 10:46 PM	#6
Mike Sertic Regular Crew Join Date: Apr 2009 Location: San Diego, CA Posts: 43	Has anyone looked at how the digital extender functions in the 720p formats? Does it just window the center 1280x720 portion of the sensor and record that? The fact that it is a 1.5 extender suggests that might be the case, which could probably deliver pretty respectable quality on par with the regular 720p modes.