xti & 430 EX II

I picked up a 430 exII the other day and I'm getting some inconsistant readings. According to the Manuel the camera and flash should recognize each other and the flash should find the zoom distance of the lens. when this happens a little icon shows up to the right of the zoom setting letting you know the two are linked.

My problem is that first this isn't happening, and when I mess around with the zoom setting on the flash manually eventually it shows up. after I take a shot the zoom setting shows no input, just lines as if no zoom is set. Also when it does show up it reads as 28mm. My lens is 30mm. So I'm confused that even when it shows up it's not reading correctly. When it shows 28 is that the closest it gets to 30? Is it taking into account the crop factor? a 30mm on an xti is really like a 50mm. So i'm wondering if the inconsistency is due to a bad connection on the hot shoe or could the lens being a sigma and not a canon have something to do with it?

thanks in advance.

Not all lens report distance. From what I understand canon lenses with the USM motors do report distance, but those without do not. I dont know about the sigma, but that might be part of the problem. Also if you are bouncing your flash that icon goes away unless you are manually adjusting the zoom control.

gonzogolf wrote in post #8159060
Not all lens report distance. From what I understand canon lenses with the USM motors do report distance, but those without do not. I dont know about the sigma, but that might be part of the problem. Also if you are bouncing your flash that icon goes away unless you are manually adjusting the zoom control.

thanks, i didn't realize that it went away on a bounce flash. What about the distance reading? even on manual the flash only reads 28mm. I've tested setting it at 28 and 50 and can't see any difference. just wondering, if it's not reading the distance, is it also not reading the sensor.

The focusing distance has nothing to do with this. What the flash shows in the display is the current focal length of the lens. If it's a zoom lens, that may change, but for a fixed 30 mm, it will remain the same.

(The OP used the phrase "zoom distance", but that's something which doesn't really exist.)

Assuming the camera can read the focal length information from the lens, and that the 430 EX II reflector zoom operates properly, the flash is supposed to show 28 mm when using a 30 mm lens. The flash has fixed settings, so it will use the nearest wider than the lens.

If the camera is an APS-C camera, which the 400D is, and the flash is set to act accordingly, then a little icon to the right of the flash zoom setting will show that the zoom reflector's position has been adjusted to match the narrower field of view of such a camera.

If the flash shows "Zoom -- mm", then it's either in the bounce position, or the zoom mechanism is out of order. With the flash pointing forwards, it's supposed to show the focal length of the lens and the APS-C icon, when applicable.

Provided the camera isn't in any of the "idiot modes", you can use the buttons on the flash to change zoom setting, flash mode etc.

As a side note....My 50 f1.8 on my XTi reports focal length to my 430EXII (when pointed forward of course).

All my lenses do too, but they are all Canon.

ALL lenses from ALL manufacturers will transmit focal length information to the flash so that the zoom head position will be correct.

Only some lenses transmit focal length information to the ETTL II programing to help get a better flash exposure. http://photonotes.org …s/eos-flash/#distancedata

There is a difference.

dgoakill wrote in post #8159014
Also when it does show up it reads as 28mm. My lens is 30mm. So I'm confused that even when it shows up it's not reading correctly. When it shows 28 is that the closest it gets to 30? Is it taking into account the crop factor? a 30mm on an xti is really like a 50mm.

thanks in advance.

The 430EX II flash head reflector zooms so that it can match the focal length of the lens in use. A wider lens needs a wider flash coverage, but lighting up more area takes more power. To conserve power (and batteries) The flash head reflector moves in steps to match 24mm, 28mm, 35mm, 50mm, 70mm, 80mm, and 105 mm field of view.

If you are using a crop camera, the crop should be applied to the flash head as well.

With your 30mm(48mm with 1.6 crop) lens the flash head should actually be set to 35mm or even 50mm to get maximum flash power and battery life. If the flash head is at 28mm you are just wasting light that won't be in the photo.

Third party (and probably some Canon) lenses sometimes don't fully communicate the crop factor with Canon flashes. You might be wasting some power shooting at wider coverage than you need. Or the flash may actually be applying the crop factor to the flash head but not reporting it.

Examples:

My Sigma 17-70 sets the flash to 24mm at 17mm and then stays there until the lens is at 28mm. It then follows the normal steps of 28-35-50-70 and stops at 70. It reports 24-35-50-70, but one day I tried manually zooming the flash head and discovered that when it reported "70" the flash head was actually zoomed all the way out to the 105 position.

So with your Sigma 30mm, the flash head should automatically be at 35mm but the flash might say 28mm even though it is really at 35.

If you have too much time on your hands (like me), you could study the various positions of the flash head as it moves in and out, and you might be able to identify where it actually is.

Here is a slightly confusing thread on the subject: https://photography-on-the.net …9519&highlight=​flash+zoom

msowsun wrote in post #8162095
The 430EX II flash head reflector zooms so that it can match the focal length of the lens in use. A wider lens needs a wider flash coverage, but lighting up more area takes more power. To conserve power (and batteries) The flash head reflector moves in steps to match 24mm, 28mm, 35mm, 50mm, 70mm, 80mm, and 105 mm field of view.

If you are using a crop camera, the crop should be applied to the flash head as well.

With your 30mm(48mm with 1.6 crop) lens the flash head should actually be set to 35mm or even 50mm to get maximum flash power and battery life. If the flash head is at 28mm you are just wasting light that won't be in the photo.

Third party (and probably some Canon) lenses sometimes don't fully communicate the crop factor with Canon flashes. You might be wasting some power shooting at wider coverage than you need. Or the flash may actually be applying the crop factor to the flash head but not reporting it.

Examples:

My Sigma 17-70 sets the flash to 24mm at 17mm and then stays there until the lens is at 28mm. It then follows the normal steps of 28-35-50-70 and stops at 70. It reports 24-35-50-70, but one day I tried manually zooming the flash head and discovered that when it reported "70" the flash head was actually zoomed all the way out to the 105 position.

So with your Sigma 30mm, the flash head should automatically be at 35mm but the flash might say 28mm even though it is really at 35.

If you have too much time on your hands (like me), you could study the various positions of the flash head as it moves in and out, and you might be able to identify where it actually is.

Here is a slightly confusing thread on the subject: https://photography-on-the.net …9519&highlight=​flash+zoom

thanks, that makes sense. So it is working mostly correct. I didn't see much difference between 28 and 50. but I'll definitely check to make sure it's set right.