HX9V/20V/30V: Does 60i (or 30p) deliver better IQ over 60p in Low Light?

Started Dec 3, 2012 | Discussions thread
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Jamon47
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HX9V/20V/30V: Does 60i (or 30p) deliver better IQ over 60p in Low Light?
Dec 3, 2012

That question was asked more than once recently on DPReview forums and as far as I am concerned with no definite answer... or at least not one that I understood !! So I did a little straightforward test with my HX9V to see if videos shot in Low Light (LL) and Very Low Light (VLL) deliver visibly different Image Quality (IQ) when shot in 1080p60 or 1080i60.

As I am not an expert in how these cameras internally behave when shooting videos, I hope that those of you that have that knowledge will share comments/views and correct me if I'm wrong!

I understand that when shooting in 1080p60 the HX9V (and I assume the HX20V/30V too) image sensor operates at 60fps (aka images-per-second) and that when shooting in 1080i60 the sensor operates at 30fps, then split the odd and even lines of each single frame/image and wrap both fields in a 60i container. So essentially, when set at 60i the HX9V sensor behaves as if the camera is set at 30p. Thus the question: does 60i (or 30p) deliver visibly better IQ over 60p in LL and VLL conditions?

Also I understand that when shooting video these cameras are essentially in Auto Mode (iAuto) except for EV compensation and Focus Tracking. There are also some WB settings available in "high ISO mode", which I have never used like probably the majority of owners of these cameras!

Test details:

- it is a static video test with the camera standing on a tripod in front of a pot/cup/flowers display in an almost dark room, with the lens set at the wide-angle end, about 2 feet in front of the pot

- the only light on the display is from the top, two glass shelves above, from a small incandescent bulb delivering Low Light (LL) on the display. The Very Low Light (VLL) conditions are set by putting a white sheet of paper just under the bulb, between it and the display

- the only variables from one clip to the other are the recording mode (1080i60 or 1080p60) and light conditions (LL or VLL). All clips have EV compensation set to 0

- I shot 4 clips (approx 10 sec each), 2 in 60i (in LL and in VLL) and 2 in 60p (in LL and in VLL). The clips have not been edited (they are as in-camera)

To view the clips: https://vimeo.com/jamon47 . You can also download the original clip files.

When played on my 52” TV and sitting 10 feet away, I can't see any visible differences between the clips shot under the same light conditions.

MY CONCLUSION: in a static scene, with the HX9V (and similar cameras) there are no visible advantages, from an IQ perspective, in selecting 60i (or 30p) over 60p when shooting videos in Low Light and Very Low Light conditions.

In an action scene, will the conclusion hold?

I think that the best way (maybe the only way!) to improve video IQ in low light (LL and VLL) with the HX9V (and similar cameras) is to shoot at (or close to) the wide-angle end of the lens (faster) and/or slightly overexpose with EV compensation... or turn on more lights !!

Here are frames grab from the clips, using the Sony Play Memories Home software that came with the camera. (the photos are in my gallery)



Low Light (LL) shot in 1080i60 with EV compensation set to 0



Low Light (LL) shot in 1080p60 with EV compensation set to 0



Very Low Light (VLL) shot in 1080i60 with EV compensation set to 0



Very Low Light (VLL) shot in 1080p60 with EV compensation set to 0

Sony Cyber-shot DSC-HX20V Sony Cyber-shot DSC-HX9V
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