Canon EOS 20D Service Manual page 90

Technical Information
(2) Faster speed
Besides the smaller size, the stronger drive spring affords a maximum
shutter speed of 1/8000 sec. and X-sync at 1/250 sec. (curtain speed: 2.4
ms/15 mm).
Note: For non-EOS external flash, check whether it can sync at 1/250 sec.
(3) Better control
To control fast shutter speeds, a stronger magnet is used. The shutter
control is thereby better.
Electrical X contacts are used for the sync contacts. Through the electrical
X contacts (semiconductor switch), the mechanical X contacts are switched
ON/OFF by a low voltage. Therefore, there is no contact scorching or
frictional wear. The contacts are thus highly reliable. The PC terminal has no
polarity.
Also, the battery life during bulb exposures is about 2.5 hours with a fully-
charged BP-511A.
1. Type
2. Shutter curtain type
3. Shutter curtain blades
4. Shutter curtain material
5. Drive system
6. Speed control method
7. Curtain speed
8. Shutter speed range
9. Max. flash sync
10. Signals
4) ISO speed
(1) ISO speed range
ISO 100 - 1600 can be set in 1-stop increments. When C.Fn-08-1 (ISO
speed extension) is set, an ISO speed equivalent of ISO 3200 (H) can be set.
(2) ISO auto
The ISO auto feature that sets the ISO speed automatically in Basic Zone
modes was first incorporated in the EOS 10D. However, due to user
suggestions, this feature has been revamped.
As shown in Table 008, ISO 400 (except in Portrait mode) is the basic ISO
speed. This results in good image quality while reducing the chances of
camera shake more than before. When flash is used, the main subject's
background will also look bright.
Table 007 Shutter Design Specifications
Item
Vertical-travel, focal-plane shutter
Parallelogram link type
1st curtain: 4 blades 2nd curtain: 4 blades, total 8
1st curtain: 4 blades made of KN Mylar
2nd curtain: 4 blades made of KN Mylar
1st curtain: Dedicated torsion spring
2nd curtain: Dedicated torsion spring
All speeds electronically controlled with the electrical
conduction interval of the 1st curtain's dedicated magnet and
the 2nd curtain's dedi-cated magnet. (The magnet attracts the
curtain when turned on, and releases when turned off.)
Approx. 2.4 ms/15 mm
1/8000 sec. - 30 sec., bulb
1/250 sec.
1. X-sync (electronic X), 2. 2nd curtain travel-completed signal
Specification
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