20d - Speedlite 580EX flash anomaly

[gjn]

Does anyone know if the 20d - Speedlite 580EX flash anomaly (see http://www.robgalbraith.com/ubbthreads/showflat.php?Number=324386) has
been fixed. I'd like to get a 580ex , but I'm waiting until this problem has been corrected.

[ScottE]

The reasoning in the posting doesn't make any sense. It basically states that if you used a lens wider than 24 mm on a 20D, the flash would ignore the 1.6x crop factor and set the flash at its maximum width of 24 mm as if it was on a 35 mm camera.

For example, the field of view of a 20 mm lens on a 20D is the same as the field of view of a 36 mm lens on a full frame camera, a flash setting of 24 mm should be more than wide enough. How could that lead to vignetting?

Scott

[PacAce]

Does anyone know if the 20d - Speedlite 580EX flash anomaly (see http://www.robgalbraith.com/ubbthreads/showflat.php?Number=324386) has
been fixed. I'd like to get a 580ex , but I'm waiting until this problem has been corrected.
The way I read the 580EX specs, there isn't any problem with it or the way it implements the zoom, taking crop factor into consideration. The 580EX specs says that the flash is good for 24mm to 105mm lenses and 14mm with the diffuser panel. It also goes on to say that the head zooms to cover those lens angles while taking the camera crop factor into consideration for those camera that provide the info. In other words, if you use a 24mm lens on the 20D, the 580EX will zoom the head to the 35mm postion.

No where did I see anything in the manual about it being OK to use a 17mm lens or a 20mm lens without using the wide-angle diffuser panel because, taking the crop factor into consideration, the 35mm equivalent would be convered by the 24mm zoom position. I think those people are just out on a witch hunt, if you ask me.

[robertwgross]

I think those people are just out on a witch hunt, if you ask me.

Don't we get enough of that here?

---Bob Gross---

[Jon]

Interesting that the guy making the post hasn't seen the problem, or even read the 580EX manual. Canon's implemented the algorithm consistently as far as I can see. If you're using a lens of 24 mm f.l. or longer, the flash auto-adjusts. If you're using something wider, pop down the wide auxiliary lens (which isn't automated). Don't try to outsmart the flash by saying you're at a smaller form factor. With the aux. lens in place, the flash can zoom appropriately for any of Canon's UWA zooms without your needing to pop the lens up and down in mid-shoot. If Canon had set it up so you could use a wider-than-24 lens on the 20D and get auto-zoom of the head down to 15 mm, they'd be carping because the camera/flash didn't realize when you zoomed back below that and didn't cover the FoV.

[gjn]

Thanks to all for the info.
George

[slin100]

I think the complaint has some merit. Say I use a 17-40. This has a 35mm-equivalent FOV of a 27-64mm lens. Anytime the lens is between 17-23mm, I would have to flip down the wide-angle diffuser. Basically, the 580EX doesn't use the 24mm or 28mm zoom settings. I can see how this could be annoying.

Contrast this with a 24-70 lens on a full frame camera. You get approximately the same FOV and you don't have to worry about flipping down the diffuser.