The fault has been widely reported online, and appears to show the exposure value changing as a result of the top LCD plate light being activated when shooting in very dark conditions.
Canon UK has admitted the fault, and issued the following statement, "Canon has identified that when the LCD top light is switched on in very dark situations, the displayed exposure value may change on the EOS 5D Mark III.
Canon is now investigating the issue and will announce further details on the Canon support page in due course.
"Customer satisfaction remains Canon's top priority and we would like to apologise to our EOS 5D Mark III customers for any inconvenience cause," said the camera company in a statement.
The 5D Mark III was announced in March, as an upgrade to the extremely popular Mark II. It features a 22.3 million pixel sensor, and retails for around £3,000.
Canon has also experienced problems with its flagship model, the 1DX, causing its release date to be pushed back until June.
The spokesperson was unable to give an estimated date as to when investigations into the 5D Mark III issue would be completed and shipping would resume, stay tuned for more details as they emerge.
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Amy has been writing about cameras, photography and associated tech since 2009. Amy was once part of the photography testing team for Future Publishing working across TechRadar, Digital Camera, PhotoPlus, N Photo and Photography Week. For her photography, she has won awards and has been exhibited. She often partakes in unusual projects - including one intense year where she used a different camera every single day. Amy is currently the Features Editor at Amateur Photographer magazine, and in her increasingly little spare time works across a number of high-profile publications including Wired, Stuff, Digital Camera World, Expert Reviews, and just a little off-tangent, PetsRadar.