iMac FaceTime HD camera shows no image/black image

There's an iMac whose FaceTime HD camera isn't displaying video images in applications like FaceTime, Photo Booth, or QuickTime video recorder.

OS X El Cap shows that the camera is attached and registered properly in the About This Mac - System Report.

• fresh new install of El Cap on a Fusion drive. Previously the camera worked well with Yosemite.
• the green light indicator flashes on/off repeatedly and irregularly when you start an application that uses the camera
• there are no error messages or anything about no cameras being attached.
• pressing the big button to take a photo in Photo Booth has no effect. The button is on the screen, but isn't pressable.
• Skype is not installed

What steps can I take to get the camera to capture and display video properly?

Attempts to fix

• reset the NVRAM

Items to investigate

• should I reset the SMC?
• will the Apple Hardware Test reveal anything

I recently opened this iMac to install an SSD. All cables were re-attached properly.

Solution 1:

I have had this problem in the past. I found my answer here. http://osxdaily.com/2013/12/27/fix-there-is-no-connected-camera-error-mac/

Open terminal from the utilities folder in the applications folder. Type sudo killall VDCAssistant into terminal and click enter. Then, enter sudo killall AppleCameraAssistant (may say "No matching processes were found", this should be fine). That should do the trick.

Solution 2:

Resetting the SMC solved the camera issue. It's now working as per normal.

All that involves is shutting down the machine, removing all power from the computer for 15 seconds, and restoring power.

Solution 3:

I was having this problem with my Mac - the screen was completely black when trying to use the camera for Skype etc. Simply rebooting and unplugging my computer, closing all apps, empty the cache, fixed the problem instantly!