Flash spots

[shrumtrop]

It ONLY happens when using the ON-CAMERA BUILT-IN flash unit.

What causes them and how to prevent it?

http://poundit.ca/gallery/albums/spooky8/6_G.jpg


mind you it never happens when I've got a 420EX Speedlite attached.

[jpmccormac]

I've seen this phenomenon before. I believe it's caused by the light from the flash bouncing off particles (dust?) in the air. It seems to be enhanced by the on camera flash due to its close proximity to the lens. I've duplicated when it's snowing by firing the flash in daylight during a snow fall. Makes a nice effect then.

[FlyingPete]

I have had this exact same problem at a staff party, it was a beach theme (at night), so there was a lot of sand, and also a smoke machine running. I was also using the internal flash. I put it down to the smoke machine causing it, I may be wrong though. The smoke machines vaporise a fluid (similar to glycol or anti-freeze), it could be that as these are vapour particles, they all act like little partial mirrors, a bit like peoples eyes. I have noted that I only get issues with red eye when using my internal flash, never with my 420EX.

[rangersvtsplash]

notice little red eye too in the wounderfull ladies their :)
i have not ran into this yet but ive ran into like strange lights that streak all over and turn purple and stuff. wierd. could you not of had like dust on the lense at the time?

[pradeep1]

Those are NYPD fresh recruits!? Wow! :)

[phili1]

The only way it could happen is in fog or a heavy smoke filled room, the angle of the flash causes a bounce back effect. Thats a first for me.