| C.Fn | Custom Function | No. | Setting |
| 00 | Focusing Screen | 0 | N Ec-N, R |
| 1 | L Ec-A, B, C, C II, C III, D, H, I, L | ||
| 01 | Viewfinder Display During Exposure | 0 | Disable |
| 1 | Enable | ||
| 02 | Shutter Release without Card | 0 | Enable |
| 1 | Disable | ||
| 03 | (Unused) | ||
| 04 | Shutter Button/AE Lock Button | 0 | AF/AE lock |
| 1 | AE lock/AF | ||
| 2 | AF/AF lock (no AE lock) | ||
| 3 | AE/AF (no AE lock) | ||
| 05 | Manual Tv/Av Set. for Manual Exposure | 0 | Tv: Main Dial, Av: Quick Control Dial |
| 1 | Tv: Quick Control Dial, Av: Main Dial | ||
| 2 | Tv: Main Dial, Av: Quick Control Dial (available with the lens detached) |
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| 3 | Tv: Quick Control Dial, Av: Main Dial (available with the lens detached) |
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| 06 | Exposure Level Increments | 0 | 1/3-stop, exposure compensation 1/3 |
| 1 | Full-stop, exposure compensation 1/3 | ||
| 2 | 1/2-stop, exposure compensation 1/2 | ||
| 07 | USM Lens Electronic MF | 0 | After in-focus: Enable |
| 1 | After in-focus: Disable | ||
| 2 | Disable | ||
| 08 | Top LCD Panel/Rear LCD Panel | 0 | Number of remaining shots/file number |
| 1 | ISO/number of remaining shots | ||
| 2 | ISO/file number | ||
| 3 | Number of images saved in the folder/ Number of remaining shots |
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| 09 | Bracketing Sequence/Auto Cancel | 0 | 0 → — → + /Enable |
| 1 | 0 → — → + /Disable | ||
| 2 | — → 0 → + /Enable | ||
| 3 | — → 0 → + /Disable | ||
| 10 | AF Point Illumination upon Focusing | 0 | Lights |
| 1 | Does not light | ||
| 2 | Lights (not dimmed) | ||
| 3 | Lights brightly | ||
| 11 | AF Point Selection Method | 0 | Left/Right: AF point selector + Main Dial |
| Up/Down: AF point selector + Quick Control Dial |
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| 1 | Left/Right: Exposure compensation button + Main Dial |
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| Up/Down: Exposure compensation button + Quick Control Dial |
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| 2 | Left/Right: Quick Control Dial only | ||
| Up/Down: Assist button + Main Dial | |||
| 3 | Left/Right: FEL button + Main Dial | ||
| Up/Down: FEL button + Quick Control Dial | |||
| 12 | Mirror Lockup | 0 | Disable |
| 1 | Enable | ||
| 13 | Number of AF Points/Spot Metering | 0 | 45 points/center |
| 1 | 11 points/linked to the active AF point | ||
| 2 | 11 points/center | ||
| 3 | 9 points/linked to the active AF point | ||
| 14 | E-TTL II | 0 | Evaluative |
| 1 | Average | ||
| 15 | Shutter Curtain Sync. | 0 | 1st-curtain sync. |
| 1 | 2nd-curtain sync. | ||
| 16 | Safety Shift Setting | 0 | Disable |
| 1 | Enable | ||
| 17 | AF Point Activation Area | 0 | Disable |
| 1 | Expands by one point (7 points) | ||
| 2 | Expands automatically (max. 13 points) | ||
| 18 | Switch to the Registered AF Point | 0 | Assist button + AF point selector |
| 1 | Assist button | ||
| 2 | Switches only when the assist button is ON | ||
| 19 | Lens AF Stop Button Function | 0 | AF stop |
| 1 | AF start | ||
| 2 | AE lock while metering | ||
| 3 | AF point: Manual → Auto, Auto → Center | ||
| 4 | ONE SHOT  AI SERVO |
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| 5 | Image Stabilizer (IS) start | ||
| 20 | AI Servo Tracking Sensitivity | 0 | Standard |
| 1 | Slow | ||
| 2 | A little fast | ||
| 3 | A little fast | ||
| 4 | Fast | ||
| 21 | AI Servo continuous shooting and shooting priority (Available only with the EOS-1D Mark II; not integrated in EOS-1Ds Mark II) | 0 | Disable |
| 1 | Enable |