Tag Archives: Digital single-lens reflex camera

Low light image quality test: Nikon 1 V2 and J1, Lumix GH-2 and GH-4

I tested the low light image quality of the Nikon 1 J1 (electronically the same as the Nikon 1 J2 and the Nikon 1  V1), the Nikon 1 V2, the Lumix GH-2 and the Lumix GH-4.

The Nikon 1 is a 1″ sensor camera with a 10 MP image resolution and the V2 has just over 14 MP. The Nikon 1 is also an interchangeable lens camera.

The Lumix cameras are micro-four thirds sensors. In the 3:2 ratio in which these photos were taken, both have just over 14 MP of image resolution.

The Nikon 1 camera images were shot with the 1 Nikkor 18.5mm lens, at f/1.8 to f/2.5. The cameras were set to Program mode. White balance was set to Auto.

The Lumix cameras were shot with the Lumix 14-42mm kit lens, at 25mm (equivalent to the Nikon 18.5mm lens field of view) at about f/5.6. The cameras were set to Program mode and white balance was set to Auto. I realized afterwards the GH-4 was also set to a “Custom” photo setting that I use to reduce the highlights so it was not quite identical to the GH2.  The 1 Nikkor prime lens is also sharper than the Lumix kit lens.

These are 1:1 extractions of RAW images from Lightroom 5.x. All shots are at ISO 800 as my goal was to test low light situations.  Noise reduction and sharpness setting were what ever the default was at – thus, no attempt was made to clean up the noise. These tests are not laboratory quality – but the kind of tests that us hobbyists do to better understand our gear!

You can click on any photo to see the full size image.

LOWLIGHT EXAMPLES AT ISO 800

Nikon 1 J1

J1-800

Nikon 1 V2

The V2 shows a slightly higher noise grain than does the J1 (V1 equivalent).  However, the J1 is a 10 MP sensor and the image enlargement is not the same. When the J1 is resized to match the V2, the noise grain is closer in appearance to the J1.

Also note that in the smaller sensor J1 and V2, magenta chromatic aberration is apparent at lower left. This is easily fixable in Lightroom.  Also, those faint pink splotches captured in the V2 images were captured to some degree with all the cameras. There is a reflection from something going on – I just never noticed it before.

V2-800

Lumix GH-2

Interesting to see that the GH-2 had a lower exposure selection. Not shown, but an open window to the left of this section of the photo was bright for all of these photos.

There appears to be a very slight bit of chromatic aberration at lower left or at least some slight flaring at the high contrast points.

Lumix800

Lumix GH-4

The GH-4 did better on the auto exposure, white balance and the chromatic aberration. Even though the GH-4 is using the exact same lens as was used on the GH-2 photo above. That implies the GH-4 is doing some image processing on this RAW file that the GH-2 does not do. While there are differences in white balance making the grain harder to see in the GH-2, manually adjusting the exposure in Lightroom showed fairly similar levels of grain.

GH4-800

LOWLIGHT COMPARISON J1 VERSUS V2 AT ISO 1600

J1 ISO 1600 RAW

J1-ISO1600

J1 ISO 1600 RAW processed with LR noise reduction

J1-ISO1600-Processed

V2 ISO 1600 RAW

V2-ISO1600

V2 ISO 1600 RAW processed with LR noise reduction

V2-1600Processed

IMAGE RESOLUTION 1:1

The following is not a fair test. The Nikon 1 cameras used the 18.5mm prime lens while the Lumix used the 14-42mm kit lens. Unfortunately, I do not have a Lumix prime lens (25mm) which is needed to make this test fair.

What this does show is that the Nikon 1 with the prime lens is very sharp – perhaps sharper or at least on par with the 4/3ds camera with the kit lens. Each photo taken with the lowest ISO setting.

Nikon 1 J1 – ISO 100

J1-100

Nikon 1 V2 ISO 160

V2-160

Lumix GH-2 ISO 160

GH2-160

IMAGE RESOLUTION 3:1 ENLARGEMENT

Nikon 1 J1 – 10 MP sensor

J1-100-3

Nikon 1 V2 14+ MP Sensor

Because the J1 has fewer pixels, the 1:1 image above shows a wider area. Still, it is surprising how good the 10 MP image looks compared to the 14+ MP image.

V2-160-3

J1 ISO 100 Resized

With the images reset to roughly equal sizes, the greater resolution of the V2 becomes apparent. Here, the J1’s 10 MP image is enlarged to match that of the higher resolution V2. Bear in mind that these are really bad case/low light situations too.

J1-100-3-equal

V2 ISO 160 

If you look carefully, you can see slightly more detail on the ceramic cup, at left, and you can see more detail in the writing on the spice container in the middle.

V2-160-3-equal

J1 3:1 on the Creole seasoning container

J1-equal

V2 3:1 on the Creole seasoning container

While the resolution improvement in the V2 is visible, it does not have nearly as much visual impact as you would expect in going from 10 MP to 14 MP. Note the word “Original” in the yellow band area – the word “Original” is readable in the 14 MP version but not so well in the 10 MP version. Still … not a lot of difference, is there?

V2-equal

Lumix GH-4 ISO 400 3:1

Even at ISO 400, the GH-4 looks slightly better than the Nikon 1 V2 at ISO 160  (above). I did not shoot this test photo at ISO 200 (or using the expanded ISO setting on the GH-4, I could go as low as 100 – but there is apparently no improvement in image quality at that setting).

GH4-400-3

I did not shoot the test photo with the GH-2.

Conclusions

Small sensor cameras are doing better and better as each new product is announced.

The Nikon 1 J1 is already up to the J5 generation with 20+ MP and a better low light sensor. The V2 is presently up to the V3, with the V4 rumored to appear soon (and assumed to be similar to the J5 sensor).

The Lumix GH-2 is now up to the GH-4 generation.

In well lit areas, the Nikon 1 V2 appears to hold its own very well against the larger 4/3d sensor (the GH-2 and V2 are roughly comparable in that they were both sold around the same time). I have generally avoided shooting at ISO 800 and have probably never shot at ISO 1600! However, after these tests, I am comfortable that I can get decent results on any of these cameras at ISO 1600.

In low light, the larger sensor of the GH-2 and the GH-4 cuts the noise. You can probably shoot the GH4 at an ISO setting double that of the V2, for the same noise level. Not a big surprise.

The 4/3ds sensor also has noticeably wider dynamic range but none of these tests demonstrate that feature.

None of these cameras compete directly with full frame sensor cameras and their better low light capability. But then, they cost a tiny fraction of the cost of the full frame camera. If you are not shooting extreme low light situations, the smaller sensors may be entirely fine – which is the case for me.

I did these tests because I am thinking I may carry only the Nikon 1 V2 on some future trips. Not only is the camera small, but the lenses are small too and weigh very little compared to larger formats.

In the real world where most of us post photos to FB or Flickr, the image resolution we look at with this detailed pixel peeping just does not matter. These photos will all look fine on line.

As long as I am not shooting a lot of low light situations, there is not a big difference in image quality and I can usually control for the slightly narrower dynamic range of the 1″ sensor by shooting RAW and if necessary, using exposure compensation to control for bright highlights and dark shadows.

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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