Canon G10 Sharpness Experiment

I was looking through a few images the other day and noticed the RAW images from my Canon G10 looked less sharp than those taken with my Canon 750IS. I was a bit concerned as it had recently been repaired.

The reason for this did not occur to me at time , so I decided to do an experiment, which taught me a couple of interesting things about the camera.

The Setup

I used a PADI underwater greyscale slate that was lying around as a target. I like this slate because is has some converging lines and other elements that are good for testing sharpness.

The target was placed in a low light environment to push the camera to the limits, and simulate the sort of environment I often have when working underwater.

A tripod was setup for the cameras, and testing was done with each camera 20cm (macro mode) and 1.5m (non-macro mode) from the target to simulate near and far environments.

Test 1 – JPEG to JPEG

The 750 only outputs JPEG images, so for my first test I set both cameras as:-

• 20cm from the target
• widest zoom
• macro mode
• JPEG output
• IS OFF
• 10 second timer. (The ten second timer was used to help reduce any vibration from pushing the shutter button, as I did not have a remote cable for either camera.)

Image 1

There is little detectable difference  in image sharpness between the two cameras at 1:1 magnification. (They have slightly different zoom factors so are not quite aligned in lightroom).

I was happy with this as it indicated nothing had happened to the G10 during the repair.

Test 2 – RAW vs JPEG

So if my camera was producing sharp images in JPEG, was there a difference with RAW as I had been seeing.  To test this I compared the JPEG and RAW version (produced in the camera) of the same picture from the G10.

The test settings were:-

• 20cm from the target
• widest zoom
• macro mode
• IS OFF
• 10 second timer.

Image 2

You can see from the comparison above that the JPEG image on the left is noticeably sharper that the RAW image on the right (1:1 magnification).

I thought about this for a little while and noticed the brightness was also different between each. It then struck me:- The JPEG is processed by the camera, but the RAW image is unprocessed.

Processing the RAW image in Photoshop provides a result that is equivalent to, if not slightly sharper than the in-camera processed shot.

Test 3- Image Stabilizer

This got me thinking about the Image Stabilization and if it makes a difference.

The G10 manual says:-

When you shoot with the camera attached to a tripod, we recommend you set [IS MODE] to [OFF].

I had heard this before in a couple of other articles, and was interested to see if it had an effect.

The test settings were:-

• 20cm from the target
• narrow zoom
• macro mode
• timer OFF – to simulate vibration we turned off the timer and pushed the shutter button for each shot.

Image 3

Image 3 shows the result of having the zoom set to maximum (as far as the camera could still focus). Image 0299 on the left has the IS set to CONTINUOUS, and image 0301 on the right has IS OFF.  There is a noticeable difference between the sharpness of the two and shows the Image stabilizer does make a difference.

Interestingly:-

• Repeating the above test for the zoom set to minimum, and using the shutter button showed no difference.
• Repeating the above test using the 10 second timer to reduce vibration, and setting the zoom to minimum and maximum showed no difference.

From these results we have seen that the image stabilizer helps with sharpness when the zoom is used and shooting with the shutter button.

We also see that if a tripod and timer (or shutter release) are used, there is no improvement from the stabilizer. The image stablizer also appears to have no effect on the image when the zoom is set to a minimum.

Further info:-

• Using Your Camera Image Stabilization – has a explanation of “Ghost motion” and why you should turn of Image stabilization (IS) when not required.