Canon EOS 1D Mark III User Guide - Page 34

Shutter While based on the EOS-1D Mark II N's shutter unit, the EOS-1D Mark III's shutter unit has been improved to increase durability and to reduce the generation of dust. It is now rated for 300,000 shutter cycles. (The 1D Mark II N's shutter unit durability rating is 200,000 cycles.) To attain this level of ruggedness, surface finish and heating processes in manufacturing have been Shutter unit changed for specific highly durable parts. To increase stability and shutter precision, a photo reflector (PR) is newly employed to detect the slit-passing time. For the X-sync contact, the mechanical contact has been eliminated to prevent contact scorching and wear. By employing PR signals for the electronic X-sync contact (a semiconductor switch), reliability is improved. By optimizing the sync timing, an X-sync speed of 1/300 sec. is now attained with EXseries Speedlites. With non-EX Speedlites, the X-sync speed will be 1/250 sec., the same as the EOS-1D Mark II N's. Shutter Design Specifications Item Specification 1. Type Vertical travel, focal-plane shutter 2. Shutter curtain type Parallelogram link type 3. Shutter curtain blades 1st curtain: 4 blades, 2nd curtain: 4 blades, total 8 4. Shutter curtain materials 1st curtain: Two carbon blades, two duralumin blades 2nd curtain: Two carbon blades, two duralumin blades 5. Drive system 1st curtain: Dedicated torsion spring 2nd curtain: Dedicated torsion spring 6. Speed control method Mechanical shutter with tension released by a rotary magnet, all shutter speeds electronically-controlled 7. Curtain speed Approx. 2.3ms/21.0mm 8. Shutter speed range 1/8000 sec. - 30 sec. bulb 9. Max. flash sync. 1/300 sec. 10. Signals 1. X-sync, 2. 2nd curtain travel-completed signal External Speedlite Non-Canon flash Sync contacts Semiconductor switch (Electronic X-sync contact) PC terminal Semiconductor switch (Electronic X-sync contact) MPU Shutter PR Silent Mode A new and useful silent single shooting mode has been added to the regular complement of single shooting, high-speed continuous (10 fps), low-speed continuous (3 fps), 10-sec. self-timer and 2-sec. self-timer. During normal shooting, a magnet is used to release the tension and the reflex mirror's downward motion is spring-driven. In the silent single shooting mode, Pulse Width Modulation (PWM) control is employed to lower the effective voltage. The motor's rpm is lowered and the reflex mirror is slowly put back down. PWM control is also applied to the shutter-cocking motor to make it silent. The operation noise of the mirror going back down is approx. 77 dB for normal single shooting. In the silent single shooting mode, it is much quieter at approx. 70 dB. After shooting in the silent single shooting mode and SW2-OFF occurs, the shutter will be cocked. You can thereby control the timing of the operation noise. VIII. ROCK SOLID RELIABILITY 34