Image parameters

Just like previous PowerShot models the Pro1 provides a range of preset image parameter settings (Canon call these 'Effects'). In addition to the six presets (including Normal) there is a Custom setting which allows you to adjust contrast, sharpness and saturation by one level plus or minus. It's a pity Canon didn't take this opportunity to provide perhaps more than one Custom 'memory' and also allow owners a wider latitude or finer level of adjustment, perhaps -/+ 3 for each parameter.

Preset image 'Effects'

Normal Vivid Neutral
Low Sharpening Sepia Black & White

Custom Effect: Contrast

Adjusting the tone alters the shape of the 'S curve' used to map the linear image data captured by the sensor into the correct gamma. A lower contrast setting maintains more of the original data's dynamic range but leads to a flatter looking image. A higher contrast setting stretches the grayscale (dark to light) of the image and could lead to clipping of both shadow detail and highlights.

  Contrast Luminosity histogram

Custom Effect: Sharpness

The Pro1 allows you to control the internal sharpening of the image by a degree of one plus and minus it's "normal" sharpness.

Sharpness: Low (-) Sharpness: Normal (0)
Sharpness: High (+)  

Custom Effect: Saturation

Saturation adjustment allows you to control the strength of color in the final image. As you can see the minus and plus settings provide a fairly obvious swing in color response, this is a perfect example of where a finer level of adjustment would have been a better approach.

  Saturation 50% crop

ND (Neutral Density) Filter

The Pro1 inherits this useful feature from the PowerShot G3/G5 digital camera's. An ND filter is a simply a filter which reduces the brightness of light entering the lens (without affecting color balance - hence 'neutral'). In the SLR world an ND filter would typically be attached to the end of the lens, however in the case of the Pro1 it's inside the camera and can be inserted or removed from the path of light between the lens and the CCD via a menu option. The ND filter in the Pro1 reduces brightness by three stops (3 EV).

ND Filters have lots of uses the main ones are probably (1) when you want to reduce the shutter speed to blur movement (such as flowing water), (2) in a very bright lit situation where you want to use maximum aperture to reduce depth of field and (3) when using external flash lights (such as studio strobes) which are too powerful.

Using the ND filter to tame studio strobe lights/ internal flash

Most studio strobe systems have far too much power for prosumer digital cameras (because of their limited minimum aperture). My studio setup is normally configured to be used with a digital SLR and normal aperture would be around F13. The Pro1 was connected to the strobe system using a hot-shoe -> PC Sync terminal adapter. As you can see in the samples below even at F8.0 there is far too much light and the image is overexposed. Enabling the ND filter solves this problem.

1/100 sec, F8 1/100 sec, F8 + ND Filter