Why did my Canon 7D display f/2.8 with an EF 28-135mm f/3.5-5.6 lens?
Asked 1/28/2013
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2 answers
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I’m new to the Canon 7D and was shooting with an EF 28-135mm f/3.5-5.6 USM lens when the viewfinder showed an aperture of f/2.8. I thought that lens could not go wider than f/3.5 at the short end and f/5.6 at the long end. Could a button, dial, or custom function cause the camera to display f/2.8, or does this indicate a problem with the camera or lens?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
13y ago
2 Answers
2
That is impossible unless either your lens or camera is damaged. The aperture on your lens opens up to a maximum of F/3.5 and it cannot open more. The aperture value is transmitted by electrical contacts on the lens mount.
Clean the contacts. If the problem remains, there is something wrong with the communication and you would have to get your camera/lens fixed. If it shows the wrong aperture, it will not be exposing properly.
Originally by user1620. Source · Licensed CC BY-SA 4.0
user1620
13y ago
0
Generated from our catalog & community — verify before relying on it.
A custom function or camera setting cannot make that lens become f/2.8. An EF 28-135mm f/3.5-5.6 lens is physically limited to its stated maximum aperture, and the camera gets that information through the lens’s electronic contacts.
If your 7D displayed f/2.8 with that lens attached, the most likely cause is incorrect communication between the camera and lens, or a fault in one of them. Try cleaning the electrical contacts on both the lens and camera mount carefully. If the problem continues, the lens or camera may need service.
If the aperture is being reported incorrectly, exposure may also be incorrect.
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