Quote:
Originally Posted by grsphoto
When you change bodies, it doesn't change the laws of physics.
A 35 is a 35 no matter which body it is on... the sensor just crops in tighter on the image.
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That is correct but the sensor's cropping reduces the area of coverage to about a 50 mm so should not the flash concentrate its illumination to an area of about 50 mm?
For example with the 40D and the 16-35 mm if let the flash in automatic, the range of the flash at 35 mm is about 7 meters but if I go manual, and set it to 50 mm the range becomes 12 meters. I did test the lens and flash in automatic so that the flash was at the focal lens of the lens (35 mm), then I set the flash to 50 mm. The results with the flash at 35 mm was that the illumination resulted in an unexposed image while when set at 50 mm the illumination was better distributed; I used the side of a barn as a subjet.