Pre Flash in P-TTL mode

ian0138 · 20th February 2008

I been using K10D with a AF-360FGZ flash for a while now, pretty decent with the exposure (not fantastic), have read in other forum the pre flash fire before the main flash causes more blink. But I never notice any pre flash fire before the main flash...

So is the pre flash fire so fast that I can not tell that a pre flash has fired ?

Any kind soul can enlighthen me...

Kind of curious if the pre flash did fired or not ?

Thanks

flowerpot · 20th February 2008

most probably...

extract from Metz manual...pentax Af540 manual does not mention this AFAIK

The P-TTL flash mode with measuring preflash is a further development of the
standard TTL flash mode of analogue cameras. During the shot and before the
actual exposure, one or more almost indiscernible preflashes are executed by the
flash unit. The light reflected by the preflash is evaluated by the camera.
According to the evaluation, the subsequent flash exposure will be adjusted by
the camera to suit the situation (see the camera's operating instructions).
Depending on the camera model, the preflashes precede the main flash
by such a short interval that they practically cannot be distinguished from
the main flash! The preflashes do not contribute to the lighting of the shot.

VSonic06 · 20th February 2008

Originally Posted by ian0138

Kind of curious if the pre flash did fired or not ?

The pre-flash is very brief and fast but some people are more sensitive to flash and you could get pictures of people with closed or semi-closed sleepy eyes when using P-TTL. It happened to me more than a few times and its pretty annoying especially when taking group shots

A-mode fixes the problem of sleepy eyes

because there is no pre-flashing.

istDeS · 20th February 2008

The P-TTL pre-flash is too quick that you may not be able to notice. There are actually two bursts of light very, very close together. You should be able to “just” discern the two bursts after a while. To completely disable pre flash is to use the "A" or "M" mode on the flash and camera body on "M".

zveron · 20th February 2008

One time I was taking a group shot with AF540 and K10D with the wireless release. The pre-flash was so far away from the main flash that all of us, including me, thot the shot is done and was moving around when the main flash fire, great candid but a lousy group shot.

ian0138 · 21st February 2008

Thanks all for your respond.

Originally Posted by zveron

The pre-flash was so far away from the main flash that all of us, including me, thot the shot is done and was moving around when the main flash fire, great candid but a lousy group shot.

This is ultimate

20th February 2008	#1
ian0138 Member Join Date: Mar 2007 Posts: 148	Pre Flash in P-TTL mode I been using K10D with a AF-360FGZ flash for a while now, pretty decent with the exposure (not fantastic), have read in other forum the pre flash fire before the main flash causes more blink. But I never notice any pre flash fire before the main flash... So is the pre flash fire so fast that I can not tell that a pre flash has fired ? Any kind soul can enlighthen me... Kind of curious if the pre flash did fired or not ? Thanks

20th February 2008	#2
flowerpot Member Join Date: Mar 2007 Location: Both East n West Posts: 2,242	Re: Pre Flash in P-TTL mode most probably... extract from Metz manual...pentax Af540 manual does not mention this AFAIK The P-TTL flash mode with measuring preflash is a further development of the standard TTL flash mode of analogue cameras. During the shot and before the actual exposure, one or more almost indiscernible preflashes are executed by the flash unit. The light reflected by the preflash is evaluated by the camera. According to the evaluation, the subsequent flash exposure will be adjusted by the camera to suit the situation (see the camera's operating instructions). Depending on the camera model, the preflashes precede the main flash by such a short interval that they practically cannot be distinguished from the main flash! The preflashes do not contribute to the lighting of the shot. __________________ ~Towards Sublime Gallery~

20th February 2008	#4
istDeS Senior Member Join Date: Dec 2005 Location: "River end" Posts: 2,921	Re: Pre Flash in P-TTL mode The P-TTL pre-flash is too quick that you may not be able to notice. There are actually two bursts of light very, very close together. You should be able to “just” discern the two bursts after a while. To completely disable pre flash is to use the "A" or "M" mode on the flash and camera body on "M".

20th February 2008	#5
zveron New Member Join Date: Jul 2007 Posts: 40	Re: Pre Flash in P-TTL mode One time I was taking a group shot with AF540 and K10D with the wireless release. The pre-flash was so far away from the main flash that all of us, including me, thot the shot is done and was moving around when the main flash fire, great candid but a lousy group shot.