Canon EOS 1Ds Mark III Exposure
Being a professional model, the Canon EOS 1Ds Mark III provides only the essentials in terms of exposure modes. The modes consist of Program AE, Aperture-Priority, Shutter-Priority, and full Manual mode, along with a Bulb mode for manually timed exposures. The full Auto, Depth of Field AE and various Scene modes found on lesser Canon models are absent. The majority of the exposure modes are fairly self-explanatory, as Program AE, Aperture Priority, Shutter Priority, and Manual modes provide varying degrees of manual and automatic exposure control. While available apertures vary with the lens used, shutter speeds range from 1/8,000 to 30 seconds in all modes except Bulb, which keeps the shutter open as long as the Shutter button is depressed. (Interestingly, Bulb mode has no time limit, other than the available charge in the battery.) Canon's optional RS-80N3 remote switch and TC-80N3 Timer Remote Controller allow you to take long time exposures without having to hold your finger on the Shutter button.
A Custom menu setting can enable a "Safety Shift" option, which automatically adjusts the primary variable (aperture or shutter speed) in Av or Tv modes, if the setting you've selected won't permit a good exposure under the current lighting conditions. This could come into play if you were shooting in shutter-priority mode to achieve a motion-blur effect, but the light suddenly got brighter, pushing the required aperture value beyond what the lens could provide. In this situation, the camera would automatically boost the shutter speed the minimum amount needed to achieve a good exposure. Safety Shift can instead automatically adjust ISO from 100 to 1,600 in P, Av or Tv modes, if so enabled in the same Custom menu (C.Fn 1-8).
As you'd expect, in Program AE mode, turning the Main dial on top of the camera cycles through a range of equivalent exposure settings, allowing you to pick the best exposure with an emphasis on either aperture or shutter speed, while letting the camera determine the exposure. (This is commonly referred to as a "program shift" or "vari-program" option.)
Metering options include a 63-zone Evaluative metering mode, Partial (approximately 8.5% of viewfinder at center), Center Spot (approximately 2.4% of viewfinder at center), AF-point Linked Spot (approximately 2.4% of viewfinder), Multi-spot (a maximum of eight spot meter readings can be entered) and Center-weighted Average options. Metering range is 0 to 20 EV (at 23°C/73°F, with EF 50mm f/1.4 USM lens, ISO 100).
The Multi-Spot metering option bases the exposure on as many as eight separate readings from different parts of the image. In Multi-Spot metering mode, the central spot metering sensor is activated, and a meter reading is taken every time you press the "FEL" button on the top front of the camera. As you take successive readings, the exposure readouts in the viewfinder show the current aperture and shutter speed settings the camera has computed, while the vertical exposure level indicator shows the relative light levels corresponding to each of the points you measured. This is a pretty powerful exposure option, giving the photographer great control over the final exposure. The exposure level indicator gives you a pretty good idea of how much dynamic range the shot requires, and you can choose to give more weight to a given area of the image by taking multiple readings there.
The Canon EOS 1Ds Mark III's Exposure Compensation setting allows the user to increase or decrease the metered exposure by up to three stops positively or negatively, in one-third or one-half EV increments. An automatic exposure bracketing feature lets you set the Canon EOS 1Ds Mark III's total exposure variation (across 2, 3, 5 or 7 shots) at anywhere from +/- one-third or one-half EV, all the way up to +/- 3 EV. You can also specify the order of the sequence: 0, -, + or -, 0, + or +, 0, -.
ISO Sensitivity Options
The Canon EOS 1Ds Mark III offers regular ISO equivalents of 100, 200, 400, 800, and 1,600 with the option to use fractional settings in 1/3 EV increments (100, 125, 160...). The 1Ds Mark III also offers two additional ISO settings when enabled by C.Fn I-3 "Set ISO speed range" settings: ISO 3,200 equivalent ("H"), and ISO 50 equivalent ("L"). No Auto ISO mode is offered, though the "Safety Shift" feature mentioned previously performs a very similar function.
Noise Reduction Options
The Canon EOS 1Ds Mark III offers two types of adjustable noise reduction. The first is Long Exposure NR, for exposures one second or longer. In this mode, the camera will take a second image of the same exposure length, but with the shutter closed, to produce what is commonly referred to as a "dark frame". This frame is then subtracted from the actual exposure, which has the effect of cancelling out noisy pixels. This works for both JPEGs and RAW files. The Auto mode will attempt to automatically detect when this type of noise reduction is beneficial. The other type of noise reduction is called High ISO NR, though it is applied at all ISOs in Canons. It has the effect of filtering out noise via post processing, with some minor loss to detail. It is particularly effective at reducing chroma noise. This noise reduction is only applied to JPEGs however, keeping RAW files as they should be: unprocessed.
AE Lock / FE Lock
The Canon EOS 1Ds Mark III has the simplified AE Lock button, which unbundles the AF Lock feature from the old button on the older EOS cameras. Marked with an asterisk (*) symbol, the AE Lock button simply holds the exposure at one setting while you recompose the image. It's very useful when spot metering, but also when dealing with subjects where you want to draw your exposure from one place, while autofocusing on another. Pressing the Flash Exposure Lock ("FEL") button with an external flash mounted activates the FE Lock function, which fires the flash and locks the proper exposure for the following frame(s).
White Balance Options
The Canon EOS 1Ds Mark III offers a full range of White Balance settings, including six presets, an Auto setting, and five Custom settings. The six presets consist of Daylight, Shade, Cloudy, Tungsten, Fluorescent, and Flash. The Custom settings base color balance on an exposure, meaning you can snap an image of a white or gray card and then base the color temperature on that image, and Custom settings can be captioned for convenience. The desired color temperature in Kelvin can also be entered directly, from 2,500K to 10,000K, in 100K increments. Finally, a Personal White Balance feature allows you to create as many as five different white balance settings on a computer and load them into the Mark III for quick use. This strikes me as a great option for pros who have to shoot under highly variable lighting, or for groups of pros needing consistency between their setups. Not quite as flexible as the Custom option, because the Personal settings must be downloaded to the camera from a host computer, but arguably more powerful.
A White Balance bracketing option snaps only one image, but then writes three successive files from that single capture. Bracketing steps are from -/+ 3 stops in whole-stop increments. (Each stop corresponds to five mireds of a color conversion filter, for a total range of +/- 15 mireds. This corresponds to about a +/- 500K shift at a normal daylight color temperature of 5,500K.)
The Canon EOS 1Ds Mark III's WB Bracketing is set on the same grid as the White Balance correction control. Fairly sophisticated, the white balance correction tool lets you shift the color balance toward more or less green vs magenta or blue vs amber, using a +/-9 step grid format. You move a highlighted square through the grid to adjust the color balance, and bracketing adjustments spread the single square into a cluster of three. It's an advanced interface that greatly extends the camera's color corrective abilities.
As with most other Canon DSLRs, the EOS 1Ds Mark III also offers a Picture Style option through the LCD menu, which lets you select from Standard, Portrait, Landscape, Neutral, Faithful, Monochrome, or three User Defined settings. In each of the preset modes, the contrast, saturation, sharpness, and tone are set for specific conditions. The three User Defined options let you manually adjust each variable, then save it as a custom parameter. Finally, you can set the camera's color space to sRGB or Adobe RGB.
Highlight Tone Priority (HTP)
Also included on the Canon EOS 1Ds Mark III is Highlight Tone Priority (HTP for short), a feature that works quite well when dealing with subjects with important detail in strong highlights. (Think of the standard wedding dress shot, and you'll get the idea.) Digital cameras normally expose more like slide film: Once you hit a certain exposure level, detail just vanishes. This really becomes an issue when you're dealing with contrasty lighting and a subject with lots of highlights in it.
HTP's action is pretty subtle, but the results are very evident when dealing with strong highlights under harsh lighting. The way it works is to set the camera's base ISO up one notch, to 200, so it's only half-filling the sensor's pixels with charge during the exposure. The Canon EOS 1Ds Mark III then alters its tone curve, basically compressing the top half (that would normally be blown out) into a smaller range, thereby preserving the highlight detail. You can do this yourself when working from RAW files, you just need to significantly underexpose most of the scene, and then fiddle with the tone curve to drastically reduce the contrast, but only in the extreme highlights. If that sounds difficult, it is; it can be a real time-sink, and very difficult to make the end result look natural. Canon's HTP does this for you automatically, though, and the results look just great: You have no sense that the camera has been making radical adjustments to its tone curve; you just see all the detail in the highlights that otherwise would be missing. HTP is controlled via C.Fn II-3, giving you options to Disable (the default) or Enable it.
Continuous Shooting Mode and Self-Timer
The Canon EOS 1Ds Mark III's Continuous Shooting modes are accessed via the Drive button, and rated by Canon at five frames per second in high speed mode, for a total of 56 Large (Quality 8) JPEG shots, 12 RAW or 10 RAW + Large JPEGs before the buffer fills (at 1/500 sec. or faster). When shooting JPEGs of a very complex scene with a lot of sharp, fine detail may also compress less and result in lower buffer capacities, as was seen in our testing. You can specify the maximum burst rate in Continuous High mode between two and five frames per second, and between one and four frames per second in Continuos Low, using C.Fn III-16. You can also limit the burst depth (number of shots) in Continuous mode from two to 99 shots.
The Canon EOS 1Ds Mark III's Drive setting also accesses two Self-Timer modes, which open the shutter 10 or 2 seconds after the Shutter button is pressed, giving you time to dash around in front of the camera, or to avoid camera shake from depressing the shutter on a tripod. There is also a Mirror Lockup function to avoid camera shake due to mirror-slap.