Canon RF 10-20mm F4 L IS STM Instructions Manual page 19

Specifications
The lens length is measured from the lens mount surface to the front end of the lens.
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Add 23.3 mm/0.92 in. when including the lens cap and dust cap.
The size and weight listed are for the lens only.
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You cannot use extenders.
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Multiple exposure shooting is not possible when using this lens on certain cameras*.
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* EOS R, RP, Ra, R5, R6
There are cases in which using the zoom function during continuous shooting may result in
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conspicuous image distortion.
All data listed is measured according to Canon standards.
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Product specifications and appearance are subject to change without notice.
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ENG-18