Tag Archives: Digital single-lens reflex camera

Power zoom lenses for DSLR cameras

Panasonic launches Lumix G X Vario PZ 14-42mm F3.5-5.6 OIS pancake: Digital Photography Review.

The new Lumix “X” series lenses is an important development for shooting video on DSLRs.

DSLRs have had 3 limitations on their use for many types of video photography:

  1. lack of power zooms
  2. lack of audio controls
  3. limits on video recording time

The new lenses feature built-in zoom motors and controls. Panasonic has also announced a firmware update to several of its micro-four thirds cameras that will presumably add more zoom feature support to the cameras.

At this time, the demo video I saw showed a fixed zoom speed. I presume the firmware update will add a speed control to the cameras.  The zoom motor was audible in the camera’s built-in mic. This is yet another reason why we need to remember that audio is half the video experience – and should be using an external mic when sound is important.

Regarding audio, the lack of sound controls on DSLRs still demands use of BeachTek or other external audio mixers to get the sound right.

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The real story behind APS-C versus Four Thirds versus Full Frame sensors

With digital cameras, many enthusiasts engage in “pixel peeping” contests to super enlarge and examine every image pixel for bragging rights over whose image is sharper or has less digital noise.

This leads to pointless debates over the effectiveness of different types of camera sensors that usually leave out so many details as to be, well pointless debates.

If you’d like to know more about sensors and other aspects of photography, read what a physicist writes on his personal blog:

When I hear people claiming that the Four Thirds format is incapable of providing resolutions above 10 MP, I just laugh. Then, hearing the same “experts” say that APS-C sensors can deliver such resolutions, just because they are bigger, I don’t know whether to laugh or to cry. Stop worrying about pixels, start thinking about lenses. Or just start thinking.

via wrotniak.net: Four Thirds Sensor Size and Aspect Ratio.

His conclusion is similar to mine, outlined in my last sentence here.

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Are video capable DSLRs really smaller and lighter “run and gun”?

Numerical Reflex Digital Camera
Image via Wikipedia

vDSLRs are not smaller & lighter, nor cheaper. « I E B A Tech Thoughts.

The picture at the link says it all 🙂

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

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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