580ex II with 10-22mm lens

i dont know if this belongs in here or in the lens forum, but i read on canons website that the 580 ex II works with 14mm focal lengths. does this mean that from 10-13mm i will still have issues if the flash is mounted on my camera?

right now, with the pop up flash, i get horrible flash/shadows at 10mm OR if i have the lens hood on my 10-22.

On the 40D, the 10mm lens has the same FOV as a 16mm lens. The 580EX II covers a FOV of 14mm lens with the wide panel pulled out so you will have 2mm to spare with your lens at 10mm.

BTW, the pop-up flash has a FOV coverage of 17mm so you'll get a slight vignetting with the lens at 10mm. The issue you're having with the dark shadow cast by the lens and/or the lens hood is due to the fact that the flash light being blocked by the lens or the hood.

I've found that when using such a wide lens, I get better results using a plastic diffuser like stofen or Gary Fong so light covers the whole room. If I use just the straight flash, I will get shadows as the flash cannot cover such a wide field of view.

PacAce wrote in post #6049949
On the 40D, the 10mm lens has the same FOV as a 16mm lens. The 580EX II covers a FOV of 14mm lens with the wide panel pulled out so you will have 2mm to spare with your lens at 10mm.

BTW, the pop-up flash has a FOV coverage of 17mm so you'll get a slight vignetting with the lens at 10mm. The issue you're having with the dark shadow cast by the lens and/or the lens hood is due to the fact that the flash light being blocked by the lens or the hood.

i am confused....how can the lens have the same fov as a 16 mm lens? i mean, i realize it is a crop body, but i thought the 10-22 was made for the 20d, 30d, 40d, etc...not a huge issue to me if it really isnt 10mm, i was just curious.

i planned on buying a diffuser with the 580ex so it seems like that will help.

tomdlgns wrote in post #6050184
i am confused....how can the lens have the same fov as a 16 mm lens? i mean, i realize it is a crop body, but i thought the 10-22 was made for the 20d, 30d, 40d, etc...not a huge issue to me if it really isnt 10mm, i was just curious.

i planned on buying a diffuser with the 580ex so it seems like that will help.

What I should have said was that the FOV of the 10mm lens on the 40D has the same FOV of a 16mm lens on a full-frame camera, which is what the FOV coverage specifications for the 580EX are based on.

PacAce wrote in post #6051591
What I should have said was that the FOV of the 10mm lens on the 40D has the same FOV of a 16mm lens on a full-frame camera, which is what the FOV coverage specifications for the 580EX are based on.

ahh, yes, this makes sense now....

TY for clearing that up...just when i thought i understood the fov from a ff to a 1.3 and 1.6 i got all confused again...haha

but after reading your explanation, i understand what you are saying.