Dark area appears at high shutter speeds on Canon 5D — is the shutter failing?

Asked 4/15/2014

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My Canon 5D (original) suddenly started producing a dark/black area in one corner of the frame. It only shows up at shutter speeds faster than about 1/250s: around 1/320s there’s a faint shadow, and by 1/640s to 1/2500s it becomes a large black blob. The effect is consistent across different lenses, and even with no lens attached. It also still happens with mirror lockup enabled, so it doesn’t seem to depend on the main mirror. Looking into the camera with the mirror raised, nothing appears obviously damaged. Does this point to shutter failure, and is there any practical field fix while traveling?

Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0

Photography Stack Exchange contributor

12y ago

2 Answers

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Yes, I am almost absolutely certain that this is shutter failure. The reasons are as follows:

  1. The phenomenon is dependent on shutter speed.
  2. It is not observable below the x-sync speed.
  3. The phenomenon gets worse the faster the shutter speed is set.
  4. The light blockage is independent of lens--indeed, independent of the presence of any lens.
  5. The reflex mirror is not involved.

It should not be assumed that shutter failure always manifests as horizontal bands of uneven exposure: the curtain leaves can become bent or misaligned, or they can stick in a way that causes light blockage in an unexpected way. The curtains move so fast that it can be impossible to detect a problem through mere visual inspection.

In any case, any problems with the shutter will involve the replacement of the entire shutter assembly, and in some cases, a replacement mirror box.

Originally by user27201. Source · Licensed CC BY-SA 4.0

user27201

12y ago

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AI Answer

Generated from our catalog & community — verify before relying on it.

Yes — based on the symptoms, shutter failure is the most likely cause.

Why it points to the shutter:

  • The problem depends strongly on shutter speed.
  • It starts above about the camera’s flash sync speed.
  • It gets worse as shutter speed increases.
  • It happens with different lenses and even without a lens, so it’s not an optical issue.
  • It still occurs with mirror lockup, which largely rules out the mirror mechanism.

A failing shutter does not always show up as simple horizontal banding. A bent, misaligned, or sticking shutter curtain can create irregular dark shapes or corner blobs, especially at faster speeds when the shutter is exposing the sensor through a narrow moving slit.

There isn’t really a safe “field fix” for this if you’re not a technician. Shutter problems generally require professional service, and often replacement of the shutter assembly. Practical workaround: keep shutter speeds at or below the speed where the issue does not appear, if that’s possible for the rest of your trip.

UniqueBot

AI

12y ago

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