Some help on the settings please

[sobolik]

Ok.. so the preflashes still shoot before the shutter opens.

The question is does it affect the photo if it does. I think both happen simultaneously and it can register on the sensor. I do know that a shutter can open and be closing before a flash fires.

Here is how to find out. Take a flash photo in a totally dark room - light proof box or somewhere. (at the flash sync shutter speed or any slower speed will work) and rig the flash so it can't flash but the pre flash can. Did the pre flash register? I did and it did not register to the eye. The histogram shows nothing but that don't mean that the tiny amount was not there.

A person can do this no fuss.

Totally dark room with no windows - like my bathroom.

Camera in manual and bulb with rear curtain flash settings

Push shutter release and hold so that pre flash fires as shutter opens

Place lens cap on lens before releasing shutter and firing the flash. Done this way to prevent main flash from registering on the sensor.

Did the pre flash register? I did and mine is not detectable to the eye. Even so if it was there it would be insignificant in terms of exposing the photograph. it is like taking a photograph of a star at night using 1/1000 sec and F 8 - the star would not show up. But we know the star was there.

So the answer is no. The pre flash does not affect the photo.

 

[Chamelion 6]

I'll be trying some of this stuff out tonight. My house is over 100 years old and not very light tight anywhere.

 

[Josh66]

Ok.. so the preflashes still shoot before the shutter opens.

The question is does it affect the photo if it does. I think both happen simultaneously and it can register on the sensor. I do know that a shutter can open and be closing before a flash fires.

Here is how to find out. Take a flash photo in a totally dark room - light proof box or somewhere. (at the flash sync shutter speed or any slower speed will work) and rig the flash so it can't flash but the pre flash can. Did the pre flash register? I did and it did not register to the eye. The histogram shows nothing but that don't mean that the tiny amount was not there.

A person can do this no fuss.

Totally dark room with no windows - like my bathroom.

Camera in manual and bulb with rear curtain flash settings

Push shutter release and hold so that pre flash fires as shutter opens

Place lens cap on lens before releasing shutter and firing the flash. Done this way to prevent main flash from registering on the sensor.

Did the pre flash register? I did and mine is not detectable to the eye. Even so if it was there it would be insignificant in terms of exposing the photograph. it is like taking a photograph of a star at night using 1/1000 sec and F 8 - the star would not show up. But we know the star was there.

So the answer is no. The pre flash does not affect the photo.

Here's an even better test... (Which I would expect to have the same results.)

Do everything you did, with one exception - get the flash off camera and aim it right at your camera.

Pretty sure TTL will still work wirelessly. I know it does on the 580EX II anyway, it has it's own light meter.

If you can't make it work wirelessly, I KNOW it will work with a sync cord.


With the flash aimed at the camera, even with the (what I assume to be) low power of the TTL preflash - if anything is there, you should be able to see it.

 

[sobolik]

Ok.. so the preflashes still shoot before the shutter opens.

The question is does it affect the photo if it does. I think both happen simultaneously and it can register on the sensor. I do know that a shutter can open and be closing before a flash fires.

Here is how to find out. Take a flash photo in a totally dark room - light proof box or somewhere. (at the flash sync shutter speed or any slower speed will work) and rig the flash so it can't flash but the pre flash can. Did the pre flash register? I did and it did not register to the eye. The histogram shows nothing but that don't mean that the tiny amount was not there.

A person can do this no fuss.

Totally dark room with no windows - like my bathroom.

Camera in manual and bulb with rear curtain flash settings

Push shutter release and hold so that pre flash fires as shutter opens

Place lens cap on lens before releasing shutter and firing the flash. Done this way to prevent main flash from registering on the sensor.

Did the pre flash register? I did and mine is not detectable to the eye. Even so if it was there it would be insignificant in terms of exposing the photograph. it is like taking a photograph of a star at night using 1/1000 sec and F 8 - the star would not show up. But we know the star was there.

So the answer is no. The pre flash does not affect the photo.

Here's an even better test... (Which I would expect to have the same results.)

Do everything you did, with one exception - get the flash off camera and aim it right at your camera.

Pretty sure TTL will still work wirelessly. I know it does on the 580EX II anyway, it has it's own light meter.

If you can't make it work wirelessly, I KNOW it will work with a sync cord.


With the flash aimed at the camera, even with the (what I assume to be) low power of the TTL preflash - if anything is there, you should be able to see it.

Great idea. I don't have a remote so I can't. It should tell if the shutter opens first if the flash is very close.

I do want to buy one for a spring mission I have planned.

 

[Josh66]

I might try it in a little bit - just to confirm what I already know, lol.

I'm not sure If I can do it with my digital body though...

My 'real' body is 35mm, so it would take me a while to post the results, lol.

I have a Olympus E-300 with a Sears 50mm (Pentax mount) that I might be able to test it with. The only thing I'm unsure about is if 2nd curtain sync will work wirelessly with a Canon flash & Olympus body, and my cheap-ass Chinese wireless triggers.

This camera doesn't have a PC socket, so I can't use the PC cord. (Why do only the 'top of the line' bodies have that feature...?)

I have a Canon off camera cord though (OC-E3), I see no reason why that wouldn't work. That's probably what I'll use. Assuming I can get the Canon flash & Oly body to play nice for 2nd curtain sync.