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Avoid the Canon Powershot A620 digital camera

 
 
Don Klipstein
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      01-09-2006
In article <g1owf.32579$(E-Mail Removed)>, Logan Shaw wrote:
>Don Klipstein wrote:
>> If you shoot movies and want to do equalization on the sound track, then
>> I suggest finding software to do that. Reducing content at frequencies
>> above about 4 KHz should reduce hiss. An alternative is to hack the
>> camera to add a capacitor in the microphone circuit to reduce content at
>> higher frequencies where most of the hiss is.

>
>Assuming that the hiss is coming in at that early a stage and not through
>some crappy electronics somewhere between the microphone and the A/D
>converter.


A common weak point is condenser microphones and/or the first stage of
amplification - sometimes built into the microphone package.

>Also, if it is properly designed, everything before the A/D should have
>a signal-to-noise ratio approximately as good as the bit depth that
>the A/D converter achieves across the whole spectrum that the A/D can
>handle based on its sample rate. That is, if it's an 8-bit A/D, then
>the signal-to-noise ratio of the stuff before the A/D should probably
>be around 48 dB (6 dB per bit). And if the sample rate is 44.1 kHz,
>then the signal to noise ratio should be 48 dB or better from 20 Hz
>up to 22.05 kHz (at least).


I have heard 8-bit audio. No way my Powershot A70 has 8-bit audio,
gotta be much better than that. 8-bit in my experience is always more
distorted than the soundtracks from my camera. Since I always hear
noise and it sounds like I only get s/n estimated about 40 dB, most of
my noise would have to come from before the A/D converter. Wondering if
it would be worse if I played back through speakers with good high
frequency response?

>Of course, this could be a problem with some kind of super-cheap,
>horrid automatic gain control. The signal going into the A/D might
>be totally at the wrong level. Or maybe it's really just a bunch
>of wind noise. Obviously the microphone can't be all that hot if
>it's a miscellaneous feature in a $400 camera, considering that good
>microphones often cost $400 themselves.


I think it's mainly the microphone, maybe also the first stage of
electronics after the microphone element (possibly inside the microphone
package). Some of the noise I hear sounds like some kind of wind noise
but I always hear noise.

- Don Klipstein ((E-Mail Removed))
 
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Logan Shaw
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      01-09-2006
Don Klipstein wrote:
> I have heard 8-bit audio. No way my Powershot A70 has 8-bit audio,
> gotta be much better than that. 8-bit in my experience is always more
> distorted than the soundtracks from my camera. Since I always hear
> noise and it sounds like I only get s/n estimated about 40 dB, most of
> my noise would have to come from before the A/D converter. Wondering if
> it would be worse if I played back through speakers with good high
> frequency response?


Yeah, probably, unless the sample rate is low and you aren't even
getting much high-frequency content at all.

By the way, 8-bit audio doesn't have to sound really distorted.
If you compress the SNOT out of a signal before converting it
to 8 bit, it can sound fairly distortion-free. I did this one
time when converting some audio for use in a Palm OS program
where we needed to go with 8 bit for reasons of size. Also,
the regular telephone network uses 8-bit samples and they sound
relatively undistorted because they compress the signal within
an inch of its life.

> I think it's mainly the microphone, maybe also the first stage of
> electronics after the microphone element (possibly inside the microphone
> package). Some of the noise I hear sounds like some kind of wind noise
> but I always hear noise.


Yeah, you're probably right. I'm starting to remember hearing that
condenser mics often have high self-noise, and then it's not surprising
at all there would be a noisy pre-amp in there. This is an area where
you'd totally expect a manufacturer to skimp on parts, because it's a
little-used function and pennies count.

- Logan
 
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Racer X
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      01-10-2006

> Try using it for what it was designed for.


I did. It's designed for still *and* movies.
 
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Racer X
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      01-10-2006
Rod Speed wrote:
> Logan Shaw <(E-Mail Removed)> wrote:
>
>>Don Klipstein wrote:
>>
>>> If you shoot movies and want to do equalization on the sound
>>>track, then I suggest finding software to do that. Reducing content
>>>at frequencies above about 4 KHz should reduce hiss. An alternative
>>>is to hack the camera to add a capacitor in the microphone circuit
>>>to reduce content at higher frequencies where most of the hiss is.

>>
>>Assuming that the hiss is coming in at that early a stage and not
>>through some crappy electronics somewhere between the microphone and
>>the A/D converter.
>>
>>Also, if it is properly designed, everything before the A/D should
>>have a signal-to-noise ratio approximately as good as the bit depth
>>that the A/D converter achieves across the whole spectrum that the A/D can
>>handle based on its sample rate. That is, if it's an 8-bit A/D, then
>>the signal-to-noise ratio of the stuff before the A/D should probably
>>be around 48 dB (6 dB per bit). And if the sample rate is 44.1 kHz,
>>then the signal to noise ratio should be 48 dB or better from 20 Hz
>>up to 22.05 kHz (at least).
>>
>>Of course, this could be a problem with some kind of super-cheap,
>>horrid automatic gain control. The signal going into the A/D might
>>be totally at the wrong level. Or maybe it's really just a bunch
>>of wind noise. Obviously the microphone can't be all that hot if
>>it's a miscellaneous feature in a $400 camera, considering that good
>>microphones often cost $400 themselves.

>
>
> There's plenty of dirt cheap mics that dont have that obvious problem.


Any $5 headphones can be also used as a
good quality microphone. I know because I've
tried it. The signal is weak but the noise
is typically small.



 
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Racer X
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      01-10-2006
Don Klipstein wrote:

> I think it's mainly the microphone, maybe also the first stage of
> electronics after the microphone element (possibly inside the microphone
> package).


Just a comment, the A80 that I used to own never had
this noise problem, nor does my friend's A70. This is
an A620 issue.

 
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Tzortzakakis Dimitrios
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      01-12-2006


--
Tzortzakakis Dimitrios
major in electrical engineering,freelance electrician
FH von Iraklion-Kreta, freiberuflicher Elektriker
dimtzort AT otenet DOT gr
? "Racer X" <(E-Mail Removed)> ?????? ??? ??????
news:(E-Mail Removed)...
>
> > Try using it for what it was designed for.

>
> I did. It's designed for still *and* movies.

I agree with everyone saying that a still camera is *mainly* intented for
still pictures, while a camcorder is mainly designed for movies.So none does
both in excellence.My digital still camera (Kodak CX 7300) only takes silent
video and worse than an 1981 camcorder, but this never bothers me as it's
quite sympathetic even that bad video for my cousins in Canada, to see my
sister's fiancee brother playing the piano.For *real*movies I have the 8mm
Sony CCD-TR425E pal which is even today excellent.Of course it's no good for
overseas relatives since VCRs in USA and Canada don't playback PAL cassetes,
I asked'em.


 
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David J Taylor
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      01-12-2006
Tzortzakakis Dimitrios wrote:
[]
> I agree with everyone saying that a still camera is *mainly* intented
> for still pictures, while a camcorder is mainly designed for
> movies.So none does both in excellence.My digital still camera (Kodak
> CX 7300) only takes silent video and worse than an 1981 camcorder,
> but this never bothers me as it's quite sympathetic even that bad
> video for my cousins in Canada, to see my sister's fiancee brother
> playing the piano.For *real*movies I have the 8mm Sony CCD-TR425E pal
> which is even today excellent.Of course it's no good for overseas
> relatives since VCRs in USA and Canada don't playback PAL cassetes, I
> asked'em.


... whereas your relatives anywhere in the world /could/ most likely view
the .MOV files produced by today's digital cameras. Cameras like the
Nikon 8400 can produce 640 x 480 pixel movies at 30 fps, probably at least
as good as your 1981 camcorder, with added benefit of electronic image
stabilisation.

David


 
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Dave Martindale
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      01-12-2006
Racer X <(E-Mail Removed)> writes:

>> Try using it for what it was designed for.


>I did. It's designed for still *and* movies.


It's generally agreed (if you bothered to read the photo and video
newsgroups that you are now sending your complaints to) that most
digital still cameras make poor movie cameras at best, and most movie
cameras make poor still cameras at best.

If you really insist on having a single camera for both purposes, you
might have tried searching for discussion of that issue in these
newsgroups. Various people recommended the Canon S2IS, among Canon
cameras, as one whose video capabilities were pretty good. Nobody has
recommended the A620 for its video as far as I can remember.

I'll bet that you're spending more time now complaining about the A620
than you ever spent researching cameras before you bought one. If so,
doesn't that seem a bit strange?

Dave
 
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Rod Speed
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      01-12-2006
Dave Martindale <(E-Mail Removed)> wrote:
> Racer X <(E-Mail Removed)> writes:
>
>>> Try using it for what it was designed for.

>
>> I did. It's designed for still *and* movies.

>
> It's generally agreed (if you bothered to read the photo and video
> newsgroups that you are now sending your complaints to) that most
> digital still cameras make poor movie cameras at best, and most movie
> cameras make poor still cameras at best.
>
> If you really insist on having a single camera for both purposes, you
> might have tried searching for discussion of that issue in these
> newsgroups. Various people recommended the Canon S2IS, among Canon
> cameras, as one whose video capabilities were pretty good. Nobody has
> recommended the A620 for its video as far as I can remember.
>
> I'll bet that you're spending more time now complaining about the A620
> than you ever spent researching cameras before you bought one. If so,
> doesn't that seem a bit strange?


All completely irrelevant to the problem he actually had with the
A620, LOUSY SOUND, WITH A HIGH BACKGROUND HISS.

It should be routine to avoid that with any decently designed camera.


 
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Ron Hunter
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Posts: n/a
 
      01-13-2006
Tzortzakakis Dimitrios wrote:
> --
> Tzortzakakis Dimitrios
> major in electrical engineering,freelance electrician
> FH von Iraklion-Kreta, freiberuflicher Elektriker
> dimtzort AT otenet DOT gr
> ? "Racer X" <(E-Mail Removed)> ?????? ??? ??????
> news:(E-Mail Removed)...
>>> Try using it for what it was designed for.

>> I did. It's designed for still *and* movies.

> I agree with everyone saying that a still camera is *mainly* intented for
> still pictures, while a camcorder is mainly designed for movies.So none does
> both in excellence.My digital still camera (Kodak CX 7300) only takes silent
> video and worse than an 1981 camcorder, but this never bothers me as it's
> quite sympathetic even that bad video for my cousins in Canada, to see my
> sister's fiancee brother playing the piano.For *real*movies I have the 8mm
> Sony CCD-TR425E pal which is even today excellent.Of course it's no good for
> overseas relatives since VCRs in USA and Canada don't playback PAL cassetes,
> I asked'em.
>
>

Some of the newer digital cameras make excellent short videos. You
might check out the Kodak C330, which does full motion VGA video an
allows many options while shooting. Or go with the P850 which does
great stills, and great video. If you don't want to carry both types of
camera around, the ability to do good video and stills in one camera is
a nice feature.
 
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