Tag Archives: Digital single-lens reflex camera

Amazon selling the Lumix GH-2, with lens, for $795

Amazon selling the Lumix GH-2 for $795 – that is not a misprint and that includes the kit lens.

http://www.amazon.com/Panasonic-DMC-GH2-Interchangeable-Free-Angle-14-42mm/dp/B0043VE27Y/?tag=rumors0a-20

A major firmware upgrade is coming shortly, as well, and will add several new features.

I have this camera and love it.

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Reducing image noise in the Canon XH A1

English: Canon Xh-A1 HDV camcorder
English: Canon Xh-A1 HDV camcorder (Photo credit: Wikipedia)

The Canon XH A1 is not very old, but it is tape-based, which today seems quaint and dated!

However, the camera shoots excellent images and its 20x zoom lens remains amazing.  Even at 1440×1080 HDV, it shoots sharper and lower noise images than most of the consumer 1920×1080 camcorders.

But when comparing to my Lumix GH-2 in daylight, the XH-A1 has some image noise that resembles film graininess. Some people actually like that – I do not. I like clean and smooth images and prefer clean over sharp.

Some tips that I have discovered may be helpful to others.

If you shoot using the default camera options, the camera applies no noise reduction strategies “out of the box”. Not surprisingly, there will be some image noise.  While each scene is going to be different, I have found that by configuring the custom presets with some noise reduction options, I get very clean imagery.

I am using the following as a starting point:

  • SHP set to -3
  • Sky Detail to set to smooth/soft
  • NR2 set to “Low”.
  • Coring set to +9

Noise reduction can be improved a bit more by setting NR2 to its medium setting, or reducing the sharpness setting a bit more. These modest changes make a very large and noticeable reduction in noise. The NR1 noise reduction option only works on imagery that is not moving or barely moving, otherwise you get “ghost trails” in the video.

You can also manually set the lowest gain setting to -3db (instead of 0 db). For DSLR shooters, the video gain setting on a video camera is the same idea as setting the ISO level. More gain is the same as higher ISO, which also implies, more noise.

I remain unconvinced that the -3db setting makes any difference in noise. It does buy an addition 2x neutral density equivalent, which can be useful in broad daylight.

For maximum sharpness, I have found (as have others) that the sharpest images occur at an aperture of around f/4.0 plus or minus.

I shoot virtually everything in manual modes, usually shutter priority Tv mode, which means I adjust the neutral density filter settings and the shutter speed to get close to around f/4.0. Much above f/5.6 and sharpness starts to degrade.  You can manually set the aperture to f/9.5 and the camera’s automatic features will go as high as f/22! Images at those aperture settings produce garbage! Incredibly soft, grainy and ugly looking – don’t do that! This is the cause of widely reported and unexplained “grainy” footage captured with the XH A1 – using far too high an f-stop for the lens and sensor. The solution is to use ND filters and shutter speed to keep the f-stop in a low range.

Using these tips you can produce some very clean and very sharp video on the XH A1. I recently did some shooting using both the XH A1 and the Lumix GH-2. If you tweak your XH A1 well, it is very difficult to tell the difference between the XH A1 and the GH-2, unless you have a gigantic HDTV. The XH-A1 shoots at 1440×1080 while the GH-2 can shoot at 1920×1080/24p and /30p, or also 1280×720/60p.

  • 1080/24p is 49,766,600 pixels per second.
  • 720/60p is 55,296,000 pixels per second.

Because of how our eyes process images over time, the higher resolution image might not appear as high to our eyes. Weird, huh?

Finally, if you have noisy images already on tape that you would like to clean up, get Neat Video (http://neatvideo.com). This product is fantastic. On my quad core processor, it can take nearly one hour to clean up a minute or two of HD video, but the results are stunning. (I think they just released a new version that may drop the time to 20 to 30 minutes per minute of HD video on my configuration but I have not installed the update yet.)

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DSLRs and rolling shutter

Rolling shutter” is a video image distortion that commonly appears when using modern CMOS-based DSLRs – and also CMOS-based consumer camcorders. It manifests as a wobbly or skewed image. In the simple case, a fast pan left or right causes vertical lines to become slanted and bent. In a more typical case, portions of the image can appear wobbly if the camera – or the subject – are moving left or right.

I’ve elevated the following to its own blog post; it first appeared within the following post about the new Canon SX40IS. I also wrote about rolling shutter before.

I’ve been discovering some issues with rolling shutter on my Lumix GH-2 when using long telephoto settings that are, for me, more problematic than fast pans. Specifically, if I use the 45-200mm zoom at the 200mm setting (think 400mm full frame equivalent lens), and then switch into the ETC extended digital teleconverter mode where it isolates just 1920×1080 pixels (multiply by 2.6 times) giving a 1040mm (full frame) effective lens, the very slightest motion produces skew and wobble in the image.

Last week I shot a scene using this feature – since a 1040mm equivalent lens is compressing a huge amount of atmosphere, the thermal refraction occurring in the image made the image wobble. And sure enough, that resulted in rolling shutter issues even though the camera was locked down securely on a tripod!

Some day … an electronic global shutter will be added to CMOS sensors, I suppose. Until then, for long range video shooting, I prefer CCD imagers.

Is rolling shutter a problem? Some claim its not if you merely plan your images in advance. For those who can plan their images, this strategy may work fine.

But I shoot a lot of live events that I do not control and or which there can be only minimal planning. I am finding that DSLRs are great for shooting video:

  • For wide angle views, including handheld shots
  • For producing narrow depth of field
  • For convenience and small size (relative to a prosumer camcorder like the XH A1 or HMC-150)
  • Where you do not need real time audio monitoring and audio controls
  • Where you do not need a motor controlled zoom
  • For excellent low noise video images (especially at low ISOs)

For long telephoto shots, I find myself fighting rolling shutter far too often. I cannot control the wind. I cannot control the air temperature that causes thermals and refractions, making the image move around. As you can see in the linked articles, below, some people like all the wobbliness! I don’t!

Real video cameras have the following advantages:

  • CCD imaging (hopefully!) and no rolling shutter
  • Audio controls without adding on extras (I use a Beachtek audio mixer and external mics with my Lumix GH-2)
  • Motorized zoom control
  • Better auto focus. The GH-2 tends to hunt when shooting video so I end up using manual focus.

DSLRs (although not the GH-2) tend to suffer from false image artifacts created by aliasing and moire patterns in the images

On a typical modest screen HDTV (mine is 42 inches) it is very difficult to tell the difference between GH-2 video and XH A1 (once the A1’s noise issues are addressed – I’ll add that item to another post).

DSLRs are a fantastic tool for video, but they are not yet the be-all solution for video. But they are a wonderful additional tool to have for video shooting.

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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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