Need help with off camera TTL Flash

[Sun Devil Rob]

Hey all. I recently purchased a bracket and off cameral TTL cable for my Canon Speedlite 420EX and Digital Rebel. I'm having some problems though. When connected directly to the hot shoe, the 420EX works perfectly and the camera meters everything propertly. However, when attached to the off camera cable, the camera does not meter correctly, even though the flash triggers. This is leaving me with severely over exposed images in all modes with the exception of making adjustments in M mode. Does anyone have any suggestions or ideas as to what the problem might be? Any help would be appreciated.

Rob

 

[JerryPH]

Normally some speedlights or cameras need to be told that there is an off-camera flash being used (via changing settings on either the camera or flash). On others you cannot use eTTL off the shoe. You may need to read your manuals on this. I am more a Nikon person than a Canon... sorry that I cannot offer you more specific or definitive info.

However since you are at that level, one more step to get the flash totally off-camera is but a step away, and then welcome to the strobist world. For more info, visit http://strobist.blogspot.com and read the tutorials on lighting 101 and 102... some great stuff!

 

[Big Mike]

Welcome aboard.

That's weird, it should work just fine. It sounds like maybe some of the contacts on the cord/camera/flash are not making contact. There are 5 contacts. Make sure the cord is fully seated on both the camera and the flash. Also, make sure you are using the 'Canon Shoe Cord II'.

 

[Socrates]

Hey all. I recently purchased a bracket and off cameral TTL cable for my Canon Speedlite 420EX and Digital Rebel. I'm having some problems though. When connected directly to the hot shoe, the 420EX works perfectly and the camera meters everything propertly. However, when attached to the off camera cable, the camera does not meter correctly, even though the flash triggers. This is leaving me with severely over exposed images in all modes with the exception of making adjustments in M mode. Does anyone have any suggestions or ideas as to what the problem might be? Any help would be appreciated.

Rob

I don't know your camera BUT...

Many cameras use a pre-flash to measure camera to subject distance. The camera assumes that the flash is exactly the same distance as the camera. Try a few careful shots with the flash at the same distance and see what happens. If the shots are good, then my hypothesis is correct.

 

[Big Mike]

Actually, I don't believe that Canon E-TTL or E-TTL II, use the preflash to determine distance. It uses the preflash to determine how much light is reflecting back into the lens. Yes, distance is a factor of that, but the camera is measuring light, not distance. I have read that some Canon lenses do communicate the focus distance back to the camera, and that may (or may not) be a factor in the flash metering algorithm.

It sounds to me like the flash is just firing on full power, which makes me think that it's not in full communication with the camera, hence my suggestion to check that the shoe/cord is set properly. And to make sure that the proper cord is being used.

 

[table1349]

You don't mention what cable you bought. It sounds like an off-shoe cable problem. If it is one of the cheapies take it back and try another. I have heard of sseveral problems with the cheap chinese versions. Mostly with contact problems.

Either way, I would look at the cable first.

 

[nicfargo]

I'd second that it is a cable problem. Your camera and flash should have no problem doing what you are wanting...it has to be the cable. With the correct cable on, your camera shouldn't even be able to tell that the flash is on a cable...it should think it's sitting right on top of your camera.

 

[Sun Devil Rob]

Thanks for all the suggestions. I had been leaning towards a cable problem. I made the mistake of purchasing an eTTL cable made for Canon from Calumet. Mike, you mentioned the Canon Shoe Cord II. What about the Canon OC-E3 Off-Camera Shoe Cord?

 

[table1349]

That is the cord that Big Mike is speaking of I believe. Replaces the old OC-E2.

 

[Big Mike]

That's correct. That's the newest version, so it should also work.

 

[Sun Devil Rob]

Again, thanks everyone!

 

[TCimages]

to my knowledge ETTL can only be obtained using the wireless feature or the off camera cord 2.

edit- Didn't realize there was an OC-3.

 

[Sun Devil Rob]

As an update, the OC-E3 solved the problem I was having. Thanks again for all the brainstorming.