Optical synchronization ... Big question ?

[Yasser]

Dear All ,

I want your opinion about optical strobe sync.

From what I understand , as an electronics engineer first and a beginner photographer , is that in auto mode , the camera meters the light and sets the shutter speed , apreature and the ISO setting to match the light conditions it is exposed to when you depress the shutter.

Meaning that .... When you are shooting with optical sync. & the camera is set on Auto the electronics of the camera compensates for the dim light conditons by firing the internal flash. The Camera doesn't know that you are adding a new source of light ( which is the stobe ) thus the light metering will not be correct and may be over exposed.

Does this make sense or I am not getting things right ?

Please help in fuguring out the benefits of optical sync.

 

[kapula]

That's how I see it. But my opinion is also only theoretic as I don't have a strobe - yet. But as optical sync fires your external strobe from light pulse that your internal strobe makes there's no way your camera could know there's an external light source (other than internal flash). If you want your camera to tell your external strobe what it thinks about light conditions you need a ttl strobe. Then your camera tells the strobe what are those light conditions and so on and strobe adjusts itself to them. If you hace optic sync you'll need to do this manually (setting your camera&strobe).

 

[Yasser]

So you agree with me that strobes with optical sync is not a good choice for underwater photography and can result is wrong exposure.

Its like fooling the camera and wating for the results ....

 

[kapula]

No. You got might have gotten me wrong. There is a whole bunch of people shooting with optical sync (or without ttl anyway) with magnificcent results. I believe most pros do it without ttl. What I mean is you can't use auto (or program) mode with optically synced strobe. You have to use shutter priority or full manual and set your strobe manually too. Shooting in manual mode is a good idea underwater anyway as auto-mode doesn't produce those dramatic lights and black background what we sometimes want to have.

In a nutshell you can get excellent pictures with optic sync but you need to shoot in manual mode

 

[alcina]

I don't agree that an optical cord is not good for uw. I use one all the time with the Inon strobes and Oly 5050/Canon A series - works just peachy fine. But I do not shoot auto or program mode on either the camera or the strobe. Manual all the way

Auto modes are going to result in less pleasing results than using manual controls and having the camera/strobe do what you want it to do instead of letting it decide.

 

[alcina]

Ooops, kapula beat me to it - good answer

 

[Yasser]

Thanks for Kapula and for Alcina ...

Bottom line ... Camera set on auto with a sync stobe in not a good idea.
So for all point and shooters who don't have advanced controls .... don't think of optical sync.
AGREE ?

 

[kapula]

For u/w photography a point and shoot that doesn't have manual controls is basically waste of bottom time That's a bit harsh way to say it but you do need at least manual white balance. With that you can tell your camera that this thingie here is white and it adjusts other colours to match it. Our brain does the same and without external light or white balance tweaking you end up with blue photos. I don't mean that those photos wouldn't be nice memories of a good time while diving but if you want to take at least decent photos you need a strobe or manual white balance.

IMHO that is ofcourse

 

[alcina]

No, I don't really agree (though I absolutely agree that camera set on "auto" isn't the best choice ever underwater). Even if your camera is completely auto, you can still use an external strobe & fibre optic cord - I did with the Canon A20 (ancient).

I also used the Canon A20 with an even older model Ikelite strobe and remote slave unit. Basically the internal flash fired and triggered the external strobe - no cords, there's a little sensor attached to the strobe handle and the light from the internal must fall on this sensor to trigger the external. That strobe has no controls, so it was a matter of positioning the strobe for the correct amount of light onto the subject. It wasn't that hard to light properly and with digital's immediate feedback you can adjust on the spot.

Is it the best way? No, of course not. But if that's the gear you have, with a little patience and trial/error/correction, you can make it work

It would be helpful also to know which camera and which strobe you are using as there may be others who have used the same or similar and can chime in with more information.

 

[f3nikon]

Dear All ,

I want your opinion about optical strobe sync.

From what I understand , as an electronics engineer first and a beginner photographer , is that in auto mode , the camera meters the light and sets the shutter speed , apreature and the ISO setting to match the light conditions it is exposed to when you depress the shutter.

Meaning that .... When you are shooting with optical sync. & the camera is set on Auto the electronics of the camera compensates for the dim light conditons by firing the internal flash. The Camera doesn't know that you are adding a new source of light ( which is the stobe ) thus the light metering will not be correct and may be over exposed.

Does this make sense or I am not getting things right ?

Please help in fuguring out the benefits of optical sync.

Actually yes and no…yes in auto mode the camera’s internal light metering system will fire the internal flash if the light is too dim. But the camera does have a way to monitor and control the flash; this is done via a photo sensor outside the camera’s lens, measuring the light from the internal flash coming into the lens. And yes the external strobe's light out power canot be controlled by the camera, I use the camera's aperture opening to control this.

I use semi-manual mode or aperture priority mode. With the strobe power fixed I let the camera's shutter adjust the BACKGROUND lighting and I control the amount of FLASH striking the recording media by adjusting the aperture opening.