PDX10's 16:9 implementation - need clarification

[Graham Hickling]

Could someone please explain to me the difference, if any, between 16:9 mode as implemented by the PDX10 versus the much cheaper model like the TRV70 and 80?

I have the latter, which has enough pixels for a 2MP still image, and it definitely uses some of those extra pixels to implement 16:9 (the filed of view gets wider, etc).

Yet only the PDX10 gets marketed as having a "true" 16:9 chip. So I'm confused....

[Boyd Ostroff]

I have read that these cameras offer high res 16:9 also, but don't really know anything about them. I think they use electronic image stabilization (EIS) instead of the PDX-10's optical stabilizer. If so then you probably can't use EIS and 16:9 simultaneously, right? And of course these are only single chip cameras so the quality is not going to be as good as a 3-chipper. Also remember that the PDX-10 is marketed as part of Sony's professional line of camcorders which is separate from the consumer division.

But if you want a real answer to your question, it's time for some due diligence. Shoot the EIA 1956 test pattern in both 4:3 and 16:9 mode and compare the vertical resolution.

[Andre De Clercq]

Even with enough pixels available it's a matter of CCD chip readout strategies. The PDX10 has two different readout systems. One for 4:3 and one for 16:9. No vertical remapping of the readout is needed. the number of active lines remains 480. Other cams like pd150, DVX100A... keep the 4:3 readout in 16:9 mode, clip-off top and bottom and perform an upres (vertical remapping) starting from the reduced numbers of lines (360) to generate the 480 active pixels needed for the 16:9 anamorphic pictures. Some others just generate a letterbox output (no vert. upres)when set in 16:9 mode like the DVX100. The upres is the tricky step and needs a difficult trade-off between vert resolution loss(vertical filtering) and aliasing.

[Graham Hickling]

Thanks for your replies. I've just had a look at this pdf...

http://bssc.sel.sony.com/Professional/docs/brochures/dsrpdx10final.pdf

...and from the diagram on the second column on page two, it seems to me that the PDX10 and the TRV70 (which is what I have) use essentially the same strategy to switch from 4:3 to 16:9. That is, they both maintain 480 lines of vertical resolution, and use extra pixels to the left and right of the 4:3 pixel area to achieve the wider aspect ratio. That's what the TRV70 manual says it does - it doesnt letterbox and it's angle of view widens when 16:9 is selected.

The PDX10 will cost more given that it's a 3-chipper with DVCAM, has OIS, etc. (Maybe its the only prosumer 3-chipper that doesn't letterbox and up-res to get 16:9, hence the marketing focus on that feature???).

By the way, Boyd, the TRV70 does have EIS in 16:9 mode. It has a 2MP sensor (cf. the PDX10 which has 1.1MP) so I guess it has enough extra surplus pixels to keep EIS working even in wide mode.

[Tommy Haupfear]

By the way, Boyd, the TRV70 does have EIS in 16:9 mode.

Graham, the TRV70 employs electronics sensors (not CCD pixels) for its image stabilization which is why it can be active in its 16:9 mode.

One note about the TRV70 is that while it does have a high quality 16:9 mode that widens the angle of view the widening is lessensed as you zoom and at full zoom its the same width as using 4:3. Try it out. Place your cam at full wide and toggle 4:3 and 16:9 via the menu to see the changes in width. Now zoom 100% and try the same toggle. Not sure why this happens but effects most of the HQ 16:9 Sony single chippers.

[Tom Hardwick]

That's an interesting observation Tommy. It suggests that if you have a 10x zoom in the 4:3 mode you then have a 11 or 12x zoom in the 16:9 mode. This cannot be, but it's interesting nontheless.

tom.

[Boyd Ostroff]

<<<-- Originally posted by Tommy Haupfear : Graham, the TRV70 employs electronics sensors (not CCD pixels) for its image stabilization -->>>

I don't understand how it can do this unless it uses optical image stabilization. With EIS the sensors would tell the camera how much movement there is, but in order to compensate for that movement you will need to utilize some portion of the image outside the "normal" field of view, and that could only come from "extra" CCD pixels. But maybe the CCD has so many extra pixels that it can still handle 16:9 and EIS?

[Tommy Haupfear]

Boyd, I've never been 100% sure about the motion sensors but after doing a Google search I came up with the link below that pretty much says that Sony's Steadyshot uses both motion sensors and excess CCD pixels. The link looks pretty dated and I'm not sure what the now "Super" in new Super Steadyshot adds to the equation..

Click here

[Tommy Haupfear]

Tom, now that I've done a little digging on the Super Steadyshot, I wonder if it plays a part in the odd behavior of a TRV70 (and others) when in 16:9 mode. It would seem that a TRV70 uses both horizontal and vertical motions sensors along with excess CCD pixels for its Super Steadyshot. At full wide I would think that the image stabilization would not be nearly as active as when you zoom to 10x optical therefore giving you the full 16:9 width. Then as you zoom closer to 10x the system becomes more agressive with its pixel use and 16:9 is forced to give up some real estate.

Just an idle thought and definitely not to be taken too seriously! :)

[Boyd Ostroff]

I suspect some may disagree with the statement:

Only 270K pixels are required to deliver excellent picture quality

I believe "Super Steadyshot" is what Sony calls its optical image stabilizer (using the motion sensors and moving optics). Anyway, the distinction that article makes is that of actually measuring camera movement as opposed to estimating it based on frame comparisons. So perhaps the TRV-70 is only using 270,000 pixels to produce its "excellent picture quality" in 16:9 mode? ;-)

[Tommy Haupfear]

I suspect some may disagree with the statement:

Agreed, I believe you need at least 340k pixels. That explains the Super in the new Super Steady Shot. With single CCD Sonys starting out at 680k and going up they probably have overcame the 270k limitations of the original Steady Shot.

Sony refers to their OIS as Optical Super Steady Shot.

[Boyd Ostroff]

Interesting. On my VX-2000 it says:

Super SteadyShot
Digital Handycam

I didn't realize they also applied that term to EIS.

[Graham Hickling]

Interesting!

My take on this is ..... the highend Sony's use opto-mechanical systems that Sony sometimes calls "optical super steady shot". Sony cameras like my TRV70 have "super steady shot" whereby sensors detect camera movement and adjust the pixel-reading accordingly. Some other manufacturers detect movement of the image on the chip and process the image accordingly (which Sony claims results in poorer quality than their method).

I guess most people in casual conversation refer to the first as OIS and both the second and third as EIS.

[Tommy Haupfear]

I guess most people in casual conversation refer to the first as OIS and both the second and third as EIS.

I've also seen DIS (digital image stabilization) refer to non-Sony type of CCD based stabilization that lacks the motion sensors. Then you have Panasonic with their occassional DEIS..

So much for standardization!

[Michael Bott]

For the clearest explanation of why the PDX10's 16:9 mode is superior to that offered by its less expensive brothers see the following page on Creative Video's site.

http://www.creativevideo.co.uk/pages...dx10p-16x9.htm