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My daughter has recently noticed a problem with the images on her EOS 350D
when taking photographs as 1600 ISO.

I've put a copy of one up here:

http://www.zen31010.zen.co.uk/images...lipboard01.jpg

I haven't got the original alas but if you look particularly in the bottom
left, you can see faint horizontal striations. My daughter seems to think
this is a new problem.

If so, what's the cause and is there any cure?

TIA

Tim

Sorry, I can't answer your question because I have not seen this before on a
DSLR, however it's not just bottom left, it's uniform across the whole
bottom of the photo.

Are you sure that it only occurs at ISO 1600?


"Tim Downie" <> wrote in message
news:...
> My daughter has recently noticed a problem with the images on her EOS 350D
> when taking photographs as 1600 ISO.
>
> I've put a copy of one up here:
>
> http://www.zen31010.zen.co.uk/images...lipboard01.jpg
>
> I haven't got the original alas but if you look particularly in the bottom
> left, you can see faint horizontal striations. My daughter seems to think
> this is a new problem.
>
> If so, what's the cause and is there any cure?
>
> TIA
>
> Tim
>
>
>

"Ali" <> wrote in message
news:qv-dnc94JZ-...
> Sorry, I can't answer your question because I have not seen this before on
> a DSLR, however it's not just bottom left, it's uniform across the whole
> bottom of the photo.

I know, it's just most apparent there.
>
> Are you sure that it only occurs at ISO 1600?

I couldn't see it on her other photos that were taken on lower ISO settings
so it does seem to be only on the highest sensitivity setting.

Tim

On Wed, 12 Mar 2008 20:58:04 -0000, in rec.photo.digital "Tim Downie"
<> wrote:

>
>"Ali" <> wrote in message
>news:qv-dnc94JZ-...
>> Sorry, I can't answer your question because I have not seen this before on
>> a DSLR, however it's not just bottom left, it's uniform across the whole
>> bottom of the photo.
>
>I know, it's just most apparent there.
>>
>> Are you sure that it only occurs at ISO 1600?
>
>I couldn't see it on her other photos that were taken on lower ISO settings
>so it does seem to be only on the highest sensitivity setting.

Any way this might be heat related? The sensor is affected by heat. The
hotter it gets the more noise and high iso will magnify the issue.

Agreed, heat and humidity aren't particularly helpful to sensors.

It maybe worth taking some test shots in similar conditions at different
ISO's and shutter speeds (including long exposures), etc to pin point when
it's at it's worse. Do the lines appear in the same place every time, in
different places, etc.

Really, with an issue like this, I very much doubt it's going to be an easy
DIY fix, so personally I would get it looked at by a professional/Canon
Service Centre. If you do, let us know what they find.


<> wrote in message
news:...
>
> Any way this might be heat related? The sensor is affected by heat. The
> hotter it gets the more noise and high iso will magnify the issue.

On 12 mar., 20:42, "Tim Downie" <timdownie2...@obviousyahoo.co.uk>
wrote:
> My daughter has recently noticed a problem with the images on her EOS 350D
> when taking photographs as 1600 ISO.
>
> I've put a copy of one up here:
>
> http://www.zen31010.zen.co.uk/images...lipboard01.jpg
>
> I haven't got the original alas but if you look particularly in the bottom
> left, you can see faint horizontal striations. My daughter seems to think
> this is a new problem.
>
> If so, what's the cause and is there any cure?
>
> TIA
>
> Tim

I'm pretty sure this is sensor read noise and it was there from the
beginning. If the image was underexposed, than it becomes even more
obvious. My 20d is even worse at iso 3200. Both cameras are from
2004/2005 so...

One thing your daughter can do, is take high iso photos in raw mode.
External raw to jpg conversion (PhotoShop,...) can be much better than
in camera conversion. The striations that are obvious on in camera
jpg, mostly dissapear when raw is converted to jpg out of the camera.

Bhogi wrote:
> On 12 mar., 20:42, "Tim Downie" <timdownie2...@obviousyahoo.co.uk>
> wrote:
> > My daughter has recently noticed a problem with the images on her
> > EOS 350D when taking photographs as 1600 ISO.
> >
> > I've put a copy of one up here:
> >
> > http://www.zen31010.zen.co.uk/images...lipboard01.jpg
> >
> > I haven't got the original alas but if you look particularly in the
> > bottom left, you can see faint horizontal striations. My daughter
> > seems to think this is a new problem.
> >
> > If so, what's the cause and is there any cure?
> >
> > TIA
> >
> > Tim
>
> I'm pretty sure this is sensor read noise and it was there from the
> beginning. If the image was underexposed, than it becomes even more
> obvious. My 20d is even worse at iso 3200. Both cameras are from
> 2004/2005 so...
>
> One thing your daughter can do, is take high iso photos in raw mode.
> External raw to jpg conversion (PhotoShop,...) can be much better than
> in camera conversion. The striations that are obvious on in camera
> jpg, mostly dissapear when raw is converted to jpg out of the camera.

Thanks, I'll suggest that but I have a feeling that she saves her pictures
in RAW already.

Tim

U¿ytkownik "Tim Downie" <> napisa³ w
wiadomo¶ci news:...
> My daughter has recently noticed a problem with the images on her EOS 350D
> when taking photographs as 1600 ISO.
>
> I've put a copy of one up here:
>
> http://www.zen31010.zen.co.uk/images...lipboard01.jpg
>
> I haven't got the original alas but if you look particularly in the bottom
> left, you can see faint horizontal striations. My daughter seems to think
> this is a new problem.
>
> If so, what's the cause and is there any cure?
>
> TIA
>
> Tim
>
>
>

It looks like warm matrix (typical for higher iso setting, sometimes
smaller, sometimes much intensive),
but,
are you sure this is not the effect of resizing the image using wrong resize
filter (eg triangle filter)?

Best wishes
Martin
www.gorgolewski.com