Camera sensor noise profile of a Canon Powershot G12

I was recently reading the article The Truth about Digital ISO in Digital PhotoPro magazine, and decided to investigate the camera sensor noise profile of the Canon Powershot G12 I use for underwater photography.

Noise plays a big part in underwater photography. Available light levels are lower underwater,with less available the deeper you go. Knowing the noise performance of your camera allows you to push the ISO and get maximum performance.

I started looking at noise in the Canon Powershot series of cameras in my previous post Noise Comparison – Canon Powershot G11 vs G10.

There has been some recent talk on the web about “native ISO”, where the lower ISO of a camera is not necessarily the best for noise performance due to in-camera amplification methods. I have always thought the underwater photos taken with my Canon G12 at ISO160 were better than ISO80 or ISO100, and thought this might have been the effect of native ISO.

After reading the article The Truth about Digital ISO in Digital PhotoPro magazine, I decided to test my theory.

I setup the camera in manual mode, with a shutter speed of 1/60 sec, aperture of f2.8, and fixed white balance. A fixed white balance is required so the camera does not try and change the colour tints of the high ISO noise, giving you an incorrect result.

I placed a filter barrel and cap over the lens to block out all light, and shot a sequence of RAW images at different ISO settings from 80 to 3200.

File Size

The first interesting thing I noticed was the size of the RAW files.

canon g12 raw files

The size of the file increased as the ISO increased with more sensor noise. The ISO3200 RAW file is nearly twice the size of the ISO80 file.

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Which Canon Powershot to buy for underwater photography – G10, G11 or G12?

An email received today asked for my advice on choosing a Canon Powershot G10 or G11 for underwater photography. There are a number of things to take into account, so I thought I would cover a few in a post.

I received the following email enquiry today:-

“Carl, Please counsel with me on a camera purchase. I am putting together an underwater system and wish to use the Canon G10 or G11. I will get the Canon underwater case. Should I get a near new G10 (ie. from Craigslist – approx. $450 US) or get the G11. Please advise. Thanks! Darrell”

Thanks to Darrell for the question.

I am a keen user of the Canon Powershot G Series cameras for underwater photography, and have owned a G10 and G11 camera.

The G10 vs G11

The G10 and G11 are both good cameras and popular with many professional photographers. There are a few new functions in the G11, but the fundamental differences are:-

  • G10 has 15MP sensor, G11 has 10 MP sensor.
  • G10 has a flat screen back, G11 has a flip screen back.

The smaller sensor on the G11 provides better in-camera noise performance (see my previous post Noise Comparison – Canon Powershot G11 vs G10). I find noise can become an issue underwater, particularly when you are going deeper where there is less natural light.

Using an external flash or video light helps to keep the shutter speeds fast at those deeper depths, reducing noise.

Noise is also becoming less of a problem in post processing. Particularly if you are using Adobe Lightroom 3 with its new software engine, which is doing incredible things with noise reduction. (I have to regularly stop myself going back to old images and improving the noise, as I would never get anything else done.)

I also like the G11 flip screen for taking pictures from different angles, but in the underwater housing it does not make any difference.
Continue reading Which Canon Powershot to buy for underwater photography – G10, G11 or G12?

Noise Comparison – Canon Powershot G11 vs G10

After hearing of the Canon Powershot G11 noise improvement, I grabbed one while in Hong Kong and compared it to my G10.

I had been aware of the improved noise performance of the Canon Powershot G11 since October 2009, and thought this would be beneficial when shooting underwater where you need every bit of sensitivity you can get.

In Hong Kong on business I picked up a Canon G11 and compared it directly with my Canon G10. The results were better than I expected and show considerable improvement in noise levels.

Test Conditions

I setup the G10 and G11 next to each other on the window sill of my hotel room. Both cameras were set to the same settings at f5.0 and center weighted average.

Focusing on the same apartment block I took shots with ISO 80, 100, 200, 400, 800 and 1600 at focal lengths settings of 6.1mm and 25mm. (Due to the smaller sensor, the focal length multiplier of 4.8 gives 35 mm equivalent focal lengths of  29mm and 121mm.)

The images were compared in Adobe Lightroom.

Exposure Differences

The first thing I noticed was the G11 image was brighter than the G10 image. Analyzing the Histogram for the images, the G11 image is exposed 0.70EV to the right making it brighter.

Exposing the image more to the right is a smart idea as there is more image information in this area.

Continue reading Noise Comparison – Canon Powershot G11 vs G10