Oddity with 450D flash.

[petersmart]

I'm getting a couple of odd results from using flash on my 450D.

I bought the 450D on here last year and have been very pleased with it - over 10,000 pics taken with no probs.

But just recently I tried to use a Jessops optical slave gun to syncronise with the onboard flash to give extra light on macro shots.

But it doesn't seem to work properly - the onboard flash triggers it OK but the pics are always DARKER.

I have tried various programs, Tv, Av etc but no difference.

The other oddity is that when I try to use the small slave gun in the hotshoe it doesn't work - unless I pop up the onboard flash then both fire together and the exposure is now bright - it doesn't reduce like it does when I try to use the Jessops one as a fill in.

And this isn't the Jessops flash firing on the optical trigger because I can turn the optical trigger off and it still fires.

The onboard flash doesn't come right up so essentially it is illuminating the lens not the scene unless I put a reflector on it.

Is this a quirk with the camera or some problem with it?

I've been all through the menus and tried various settings but nothing makes any difference.

As I say I'm very pleased with the camera - it was a bargain - and this slight oddity isn't going to bother me - I would just like to know.

EDIT: Sorry - I just realised I put this in the wrong section - mea culpa.

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[HoppyUK]

Your main problem is that your optical slave is firing off the pre-flash from the camera. All auto-TTL flash systems calculate the exposure by firing a pre-flash before the shutter opens (it all happens so fast you can't distinguish it visually) and on your camera this cannot be disabled.

There is a workaround that might be okay for you, shooting macro. If you press the flash exposure lock button * that will fire the pre-flash. It will also trigger your remote flash if that's turned on, but then when you take the actual picture only the main flash pulse will fire from the camera, triggering the optical slave in sync. You have to do this for every shot though.

 

[petersmart]

Your main problem is that your optical slave is firing off the pre-flash from the camera. All auto-TTL flash systems calculate the exposure by firing a pre-flash before the shutter opens (it all happens so fast you can't distinguish it visually) and on your camera this cannot be disabled.

Thanks - that solves the problem of the slave not illuminating the macros properly.

What about having to have the on board flash popped up before the hotshoe flash works - anyone got any ideas on that?
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[HoppyUK]

Thanks - that solves the problem of the slave not illuminating the macros properly.

What about having to have the on board flash popped up before the hotshoe flash works - anyone got any ideas on that?
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Which gun is it? Is is Canon compatible? What contacts has it got on the foot?

 

[petersmart]

Which gun is it? Is is Canon compatible? What contacts has it got on the foot?

It's just a single contact on the foot - it's not particularly designed for Canon - it's the Jessop 150S which I believe has now neen discontinued.

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[HoppyUK]

It's just a single contact on the foot - it's not particularly designed for Canon - it's the Jessop 150S which I believe has now neen discontinued.

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As far as I know, the gun should fire off the hot shoe regardless. Maybe take it into Jessops and try it with a different gun if it still doesn't work.

 

[petersmart]

As far as I know, the gun should fire off the hot shoe regardless. Maybe take it into Jessops and try it with a different gun if it still doesn't work.

Bit late now, I bought it about 4 years ago just as an optical slave flash and it worked OK as a slave on my 350D and I have 3 altogether and none work on the 450D hotshoe without the on board flash popped up - or half up.

Not really worried about it - seems like an odd thing to occur.

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[HoppyUK]

Bit late now, I bought it about 4 years ago just as an optical slave flash and it worked OK as a slave on my 350D and I have 3 altogether and none work on the 450D hotshoe without the on board flash popped up - or half up.

Not really worried about it - seems like an odd thing to occur.

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I don't understand that, something isn't quite right. But either way you're a bit snookered trying to sync off the pop-up.

Best way around that is to use radio triggers, like the YN RF-602.

 

[petersmart]

I don't understand that, something isn't quite right. But either way you're a bit snookered trying to sync off the pop-up.

Best way around that is to use radio triggers, like the YN RF-602.

Well as I say it's not major problem for me as the times I use flash are fairly small - just something which puzzled me.

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[HoppyUK]

Well as I say it's not major problem for me as the times I use flash are fairly small - just something which puzzled me.

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For macro, the FEL button pre-flash trick might be a good workable solution. If you cover the pop-up when you press the FEL button, so the optical slave doesn't pick it up, you will be good to go with the main flash in sync.