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movie with Canon A75 problem

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Anonymous
December 18, 2004 6:30:53 PM

Archived from groups: rec.photo.digital (More info?)

I am still a newbie to digital cameras. I really like my Canon A75.

One question: when I use it to take a movie, sometimes I will get a pencil
or two of vertical purple light. For example, the other day we had a
birthday party and I took a movie which included a relative blowing out the
candles on a birthday cake. But when I looked at it, there were these thin
pencil beams of purple light above (and below) each burning candle. (As
each candle got blown out, the corresponding beam disappeared)

Any idea what causes this and what to do about it?

Mel
Anonymous
December 19, 2004 4:09:54 AM

Archived from groups: rec.photo.digital (More info?)

This is completely normal with CCDs when used at high frames rates such as
for video. I've noticed it years ago with my first camcorder. I see it in
the live previews of any digicam I've used. It even happens with
professional gear. Without getting technical, it is a flood over effect when
the CCD is over saturated from strong light.
John

"MB_" <mel@prodigy.invalid.net> wrote in message
news:Nz0xd.14334$N35.1359@fe06.lga...
> I am still a newbie to digital cameras. I really like my Canon A75.
>
> One question: when I use it to take a movie, sometimes I will get a pencil
> or two of vertical purple light. For example, the other day we had a
> birthday party and I took a movie which included a relative blowing out
the
> candles on a birthday cake. But when I looked at it, there were these thin
> pencil beams of purple light above (and below) each burning candle. (As
> each candle got blown out, the corresponding beam disappeared)
>
> Any idea what causes this and what to do about it?
>
> Mel
>
>
December 19, 2004 6:14:15 PM

Archived from groups: rec.photo.digital (More info?)

MB_ wrote:

>I am still a newbie to digital cameras. I really like my Canon A75.
>
>One question: when I use it to take a movie, sometimes I will get a pencil
>or two of vertical purple light. For example, the other day we had a
>birthday party and I took a movie which included a relative blowing out the
>candles on a birthday cake. But when I looked at it, there were these thin
>pencil beams of purple light above (and below) each burning candle. (As
>each candle got blown out, the corresponding beam disappeared)
>
>Any idea what causes this and what to do about it?

Unfortunately you can't do anything about it other than not record small
bright light sources in a relatively darker scene. It's normal for any
digital camera system to produce artifacts under conditions like this.

With time and practice, you'll learn what to record and how without
experiencing too many problems. The beauty of digital is that you can
practice all you want. :) 
Anonymous
December 20, 2004 1:46:48 AM

Archived from groups: rec.photo.digital (More info?)

"MB_" <mel@prodigy.invalid.net> writes:

> I am still a newbie to digital cameras. I really like my Canon A75.
>
> One question: when I use it to take a movie, sometimes I will get a pencil
> or two of vertical purple light. For example, the other day we had a
> birthday party and I took a movie which included a relative blowing out the
> candles on a birthday cake. But when I looked at it, there were these thin
> pencil beams of purple light above (and below) each burning candle. (As
> each candle got blown out, the corresponding beam disappeared)

I can reassure that it's not just your A75. without digging into the
details, when you have a relatively strong lightsource in a mostly
dark frame, you'll be prone to this. I believe it has to do with
sense amplifiers on that colum of image sensor pixels blowing out the
column, if I were a betting man.

> Any idea what causes this and what to do about it?

A proper videocamera. The bear may dance slowly, but one should be
impressed he can dance at all--sort of true for using these digicams
to do short videos as it were.

Best Regards,
--
Todd H.
http://www.toddh.net/
!