HELP!! Can't Sync

[scott_mills]

<p>Hi, looking for a little help here,<br>

My Canon Rebel XTi can no longer sync with my Interfit 150 strobes.<br>

Funny thing thing is it could for months and now all of the sudden the strobes fire after my shutter closes, I just don't get it.<br>

Some background info for my set up and how I shoot:<br>

2 Interfit strobes ex150's<br>

Fired by Canon 580 EXII (set at -2 and bounced behind me)<br>

I always fire them this way b/c I don't have a pc on the Rebel :< (and it always worked until now)<br>

How do I know it's a sync problem?<br>

-I took a photo of the strobe, set a full power, ISO 1600, f/4, 1/60s and it was UNDEREXPOSED, no flash on CMOS,<br>

BUT I was nearly blinded by the strobe firing albeit AFTER the shutter had already closed.<br>

I know I should sync w/ a cord or a radio transmitter, BUT this my ghetto method ALWAYS worked in the past.<br>

So, what the heck happened? How do I fix it with the gear I have now?<br>

Thanks<br>

Scott</p>

[lornesunley]

<p>Did you switch the camera to second curtain sync?</p>

[scott_mills]

<p>Lorne,<br>

Thanks, but that's not the problem, I never use 2nd curtain.<br>

Appreciate the input.<br>

Thanks</p>

[frank_skomial]

<p>You do not provide enough details how your on camera 580 flash operates. It will better be in flash manual mode, so optical sensors on the strobes will receive just one exposure sync flash, when the sutter is open, just like you seem telling that was working before ?</p>

<p>Is it possible that your 580 got switched into ETTL-II mode of operation ? If so, then your strobes could be released by the ETTL-II pre-flash light, and your Interfit fire BEFORE ther shutter opens?</p>

[hjoseph7]

<p>This is a long-shot, but try reseting your camera settings to factory specifications.</p>

[Mattman944]

<p>Frank is most likely correct. You should set the 580 to manual to prevent the pre-flash.</p>

<p>Even if you were successfully using eTTL before, you may have been lucky. If the weak pre-flash didn't have anything good to bounce off of, it may have not been seen by the Interfits.</p>

[scott_mills]

<p>thanks guys,<br>

it's not a pre flash problem and even if I fire the 580 directly at the strobe, it still doesn't work<br>

I'm confused, it worked earlier in the same day?</p>

[bob_sunley]

<p>Well if it worked earlier and now the two interfit units still fire but nothing shows on the image, they are either firing before the shutter opens or after it closes. Therefore something has changed in the camera or 580 flash setup. You can't tell visually if they fire before or after the shutter, so don't assume they are firing after the shutter closes.</p>

<p>So go thru the current settings and post them here so someone has a hope of helping you, cause at the moment you can't be helped as there is no information on which to base a diagnosis.</p>

 

[richard_cochran]

<p>Assuming you're not set to 2nd curtain sync, your camera is sending the fire signal at the time the first curtain is opening. Switch to a long shutter speed (1/4 second, maybe even 1 second), and you will definitely catch the flash if it's flashing late. Darken the room as much as possible and stop down the aperture so that ambient light doesn't blow everything out. Play with the shutter speed dial and you'll be able to figure out exactly how late the flash is. As an aside, using a long shutter speed like 1 second will easily let you verify that your camera isn't set to 2nd curtain sync.</p>

<p>But my guess is that even a long shutter speed won't catch the flash, because I'm guessing it's firing early. If it IS firing early, that must mean your camera is sending a signal early. That would be a pre-flash, which you need to turn off.</p>

<p>You might also want to make sure you haven't set things to FP sync (using a shutter speed faster than your sync speed).</p>

<p>I'm not at all sure what's happening. But trying a long shutter speed will help give you some information to narrow it down.</p>

[picturesque]

<p>Well I looked at the specs for your Interfit 150s. It is probably the combination of the built in infrared receivers in the Interfits, and the 580EXII that is causing the trouble. Even though you put the 580EXII into manual flash mode, it still (I guess) emits a near infrared signal of some kind (this is even NOT using the wireless system) that confuses the infrared receivers in the Interfits.</p>

<p>I ran into this problem as soon as I bought my first DSLR (a 20D) and a 580EX. I tried to use my existing Wein ProSync triggering system, which is infrared based. I soon found out that if the off camera lights were fairly close, they wouldn't fire--even with the 580EX set to manual flash mode, and the wireless system was not turned on. If I put the off camera flash farther away--it worked fine.</p>

<p>I couldn't figure it out, and called both Canon and Wein. Nobody knew anything. I gave up on the ProSyncs and went with radio slaves.</p>

[scott_mills]

<p>Thanks everyone, I will look into all of the above.<br>

Nadine, neat idea that may be it!</p>

 

[felix_mizioznikov]

<p>1st or 2nd curtain wont matter. +1 for the problem being the pre-flash. use the flash in manual mode or use a cheap manual flash, best would be using wireless transmitters like on alienbees.com website or similar. </p>

[lornesunley]

<p>Is the camera using some function on the 580 to generate a focus assist light? That could set off the strobes before the shutter opens.</p>