| X setting (X sync): |
Is the setting that causes the flash to burst in synchronization with the shutter. For some manual cameras, the X synch speed refers to the maximum speed that the camera can synchronize with the flash. |
| x-ray: |
Stands for the letter X in the phonetic alphabet. |
| Xenon: |
Is a gas sometimes used in electronic flash tubes and enclosed arc light sources. |
| XGA: |
An image resolution of 1024 x 768 pixels. |
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