Canon EOS-850 repair & common faults
Excellent coverageThe EOS-850 is one of Canon's earliest autofocus EOS bodies, an entry-level SLR built to bring electronic autofocus and a built-in flash to a budget buyer. Everything on it, shutter, aperture, wind, is run electronically off small batteries, with no mechanical backup speeds. That makes power supply and contact condition the deciding factor in most of what goes wrong with it.
Autofocus SLR, EOS system · All-electronic shutter · Built-in pop-up flash · Canon EF mount · 2 × CR123A (6 V) lithium
Common Canon EOS-850 faults
Canon EOS-850 completely dead, nothing happens
Because every function on this body is electronic, a flat or corroded battery reads as total silence rather than a partial fault, no meter, no shutter, no wind. Worth trying a fresh pair of batteries and checking the contacts aren't crusted first. If it's still dead on good batteries, the fault sits in the power circuit itself, and that's a proper bench job.
Canon EOS-850 shutter won't fire
A shutter that refuses to release with power confirmed present usually points to the shutter's own electromagnet or the release circuit feeding it, rather than anything mechanical jamming it. It's also worth confirming the camera thinks it has film wound on, some EOS bodies lock the release without a detected film state. Beyond that check, it needs opening up to say more.
Canon EOS-850 autofocus won't lock or keeps hunting
Constant hunting without a lock usually means the autofocus module isn't getting a clean signal back, whether that's the sensor itself, the drive motor coupling to the lens, or dirt in the light path. Low light or low contrast subjects will always make an EOS-850 hunt, so it's worth ruling that out first. Persistent hunting in good light points to a genuine fault needing a look inside.
Canon EOS-850 built-in flash won't fire
The pop-up flash draws heavily on the same batteries as everything else, so a flash that won't charge or fire is often the first symptom of batteries getting weak before the rest of the camera shows it. Confirm the flash is actually raised and the batteries are fresh. If it still won't charge, the fault is in the flash's own capacitor or trigger circuit rather than the batteries.
Canon EOS-850 LCD screen blank or missing segments
A display with missing or faded segments is a common age fault in this generation of LCD, caused by the panel's own seal or connection degrading over decades rather than anything electrically wrong with the camera. The camera usually still meters and fires normally underneath a poor display. It's a cosmetic and usability issue more than a functional one.
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Try it now ›Scatto is a reference tool for people who service film cameras. It explains mechanisms and quotes service data, but it cannot see your camera at the bench, so verify anything load-bearing before you act on it.