All posts by 3DM

Cameras

Canon introduces new “low light” camcorders

Canon today introduced a new high end consumer camcorder line that features 1/3 sq in CMOS sensors – but having only 1920×1080 resolution. Rather than the typical gigapixel sensors being put into many consumer camcorders or still cameras, they have opted to go with a larger sensor having fewer pixels. This means each pixel’s surface area is larger and can capture more light. That in turn means the new cameras will work much better in low light and have greater dynamic range.

Looks like the new cameras also shoot 24p, in addition to 30p (wrapped inside a 60i stream) and 60i.

More information here – watch the Canon video explanation.

Cameras, Videos

CMOS versus CCD video imaging and the “Rolling Shutter” problem

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Older video cameras used CCD-based image sensors. For various reasons, that I will explain in a moment, camera makers have largely switched to using CMOS-based image sensors on low end and even some low end semi-pro video cameras (like the Panasonic HMC-40). All of the new digital SLRs (DSLR) still cameras that also shoot video using high resolution CMOS sensors too.

But there’s a nasty problem with CMOS-based sensors that can cause the video image to resemble a shaky bowl of jello, as illustrated in this video comparison between the Canon HV20 (CMOS-based) and the Panasonic SD5 (CCD-based):

The problem is that the CMOS image sensor is read “line by line” from top to bottom.  If the image changes during the read out, then one line may be slightly offset or shifted from the previous line.  This is known as a “rolling shutter” and creates the peculiar “jello effect” since not all lines (or rows) in the image are lined up with all the others.

Old movie film cameras used a physical shutter that open and shut exposing an entire frame all at once. (Although, there are some issues with that too which we can ignore for now.)

CMOS reads the image row by row while CCDs read the entire image all at once and do not use a “rolling shutter” – hence, no jello on CCD cameras.

So why use CMOS instead of CCD? The basic reason is that CMOS uses less power and produces less heat and is less expensive. As image resolutions have increased, the size (and cost and power) of the CCD imager has gone up.

Camera makers, especially in the consumer market, are in an arms race to each have cameras featuring ever more pixels. This means most have switched to CMOS because, apparently, most consumers do not care about the jello or do not encounter it often enough.

In the DSLR world, most any camera with 10 or more megapixel resolution is CMOS. CMOS works great for most still photography. But when these DSLRs are used for video, they too suffer from awful “jello”.

There are other things to consider too – CCDs may show vertical streaks in photos when there are very bright lights (sun reflected on water, stage lights, etc) in the image.  For higher resolutions, CCDs need to be physically larger – and more expensive.

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Cameras

Shooting video with a still camera

Last summer, we were on a family camping trip in the Canadian Rockies.

I saw hardly anyone using a video camera and I was bewildered at no one using video cameras anymore?

I guess I can be a little dense – it hit me that everyone is now taking their videos with smart phones and still cameras. Hello? Duh!

I got religion and bought a factory refurbished Canon SX1 at a very deep discount. The good news is – the camera exceeds my expectations and cost a huge amount less than the fancy DSLRs. Its not the DSLR’s price that will kill you – its that you’ll soon need a $600 lens, and then a $1200 lens … and pretty soon you are broke.

The SX1 does everything those cameras do except – no interchangeable lens (which can be a good thing), no where near the narrow depth of field of DSLR, better low light performance and … well, unless you shoot professionally and need huge blow ups and narrow depth of field, the SX1 is just fine.

The bad news is that I’ve been much too busy to make much use of the SX1 yet 🙁

In good light, the camera’s 1920×1080/30p video is outstanding. I took the camera down to a nearby river and shot video of some geese and ducks and the images were stunning.

But in low light, not so good! Too noisy for me. Regardless, I bought this camera to replace carrying both a video camera and a still camera when I am out hiking or doing other activities. Its perfect for activities like these.

It won’t replace my video camera though. For controlling exposure, using external mics, recording long events, or shooting 24p – the video cameras still rule.

Link to sample video – available in 1920x1080p at the link. The compression artifacts you see are from YouTube, not from the original video.

… Oh, the SX1 is primarily a still image camera and takes very good still images. The main problem with any of these CMOS cameras is the noise (graininess) of the stills goes up rapidly and can be annoying at ISO 400 and up. This is true of all small imager cameras. Those images can be cleaned up remarkably well with noise removal software like NeatImage. ISO 400 and 800 images can end up looking near perfect after processing with NeatImage.

Do you need 1920x1080p? While I notice the difference between 1920×1080 and 1280×720, most people do not.  Many people do not even have a way to watch their own videos in full 1920x1080p.

Therefore, you can save a lot by buying a Canon SX20 or SX30, which shoot 1280×720/30p. Both run about 25 Mbps compressed video data rates, which is more bits per pixel than the 1920×1080 – but with fewer overall bits for disk storage and time spent editing on your computer. There are many camera choices available for taking 1280x720p video – and you may be just as pleased with those results as with 1920×1080/30p.