550ex and 1.6x factor

[jimbobski]

Would like to know if when using the 550ex flash with the D60, does the 1.6x factor effect the auto zoom of the flashgun. I know in theory the preflash should give the correct exposure but does the way the light falls on the subject remain the same? Is better to zoom the flash manually taking into account 1.6x factor?

[phuocle]

The 1.6X focal length multiplier has nothing to do with the amount of light falling on the subject, so you have nothing to worry about.

You're thinking about the 1.6X multiplier in the wrong sense here; it's just something that people have come up with so us humans can equate the results you'll get using lenses designed for 35mm frame of film on a digital camera. The smaller sensor, CCD or CMOS or whatever, on most SLR digitals gives you a field of view crop of the equivalent full-frame of 35mm film.

This results in the 1.6X focal length multiplier effect that people are talking about with the D30/D60/10D. Other cameras will have a different multiplier depending on their sensor - Nikon D100 has a 1.5X multiplier because of a slightly larger sensor.

Bottom line - don't worry about it. The 550EX will work fine on the 10D.

[Jeppe]

Nope, the flash will not take the 1.6 FOV Crop in considaration. The light that falls on the subject is the same, however yu will find that it will be able to deliver more lights to the corners, since the D60 drops the image, so if the flash is at 24mm and you use an 24mm lens on an ordinary filmbased EOS, it might show som fall-off in light at the corners. But since the Dxx/10D crops the image, this will not be the case.

But the light at the centre of the image will be the same. Well, you could calculate and manual zoom for better range, like, use the 105mm setting with a focal length of 168mm, in theory, the flash would light up the picture frame, but since the light fall of is more complicated than that to calculate i would stick to the autozoom as the 550 is powerful, i cant see the need for that.