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Hallo. I have an EOS 350 and a Sky box, I've been
trying to get some images from the tv. Trying to get
rid of those vertical lines you get on the photo. Using
google, the suggestions I got were :
~ don't use flash
~ try and get speed below 1/25th
~ use a tripod.

Sadly it didn't work. Anyone help on this please? TIA.

Bertie Doe wrote:
> Hallo. I have an EOS 350 and a Sky box, I've been trying to get some
> images from the tv. Trying to get rid of those vertical lines you get on
> the photo. Using google, the suggestions I got were :
> ~ don't use flash
> ~ try and get speed below 1/25th
> ~ use a tripod.
>
> Sadly it didn't work. Anyone help on this please? TIA.

In what way didn't it work?
The suggestions are correct, so you need to tell us what happened.

On Mon, 26 Oct 2009 15:37:27 +0000, Bertie Doe wrote:

> Hallo. I have an EOS 350 and a Sky box, I've been trying to get some
> images from the tv. Trying to get rid of those vertical lines you get on
> the photo. Using google, the suggestions I got were :
> ~ don't use flash
> ~ try and get speed below 1/25th
> ~ use a tripod.
>
> Sadly it didn't work. Anyone help on this please? TIA.

I would have thought that you would be more likely to get horizontal
lines from a TV pic. As you say above - a shutter speed of slower than
1/25 - ideally longer if the scene on the screen is not fast moving -
maybe a 10th of a second so that several scans are completed to avoid the
darker/brighter lines.

"Willy Eckerslyke" <(E-Mail Removed)> wrote
in message news:(E-Mail Removed)...
> Bertie Doe wrote:
>> Hallo. I have an EOS 350 and a Sky box, I've been
>> trying to get some images from the tv. Trying to get
>> rid of those vertical lines you get on the photo.
>> Using google, the suggestions I got were :
>> ~ don't use flash
>> ~ try and get speed below 1/25th
>> ~ use a tripod.
>>
>> Sadly it didn't work. Anyone help on this please?
>> TIA.
>
> In what way didn't it work?
> The suggestions are correct, so you need to tell us
> what happened.

The picture is spoilt by numerous thin lines, similar
to a finger print or lines on an OS map, but mostly in
a North/South direction.

"Bertie Doe" <(E-Mail Removed)> wrote:

>
> "Willy Eckerslyke" <(E-Mail Removed)> wrote
> in message news:(E-Mail Removed)...
>> Bertie Doe wrote:
>>> Hallo. I have an EOS 350 and a Sky box, I've been
>>> trying to get some images from the tv. Trying to get
>>> rid of those vertical lines you get on the photo.
>>> Using google, the suggestions I got were :
>>> ~ don't use flash
>>> ~ try and get speed below 1/25th
>>> ~ use a tripod.
>>>
>>> Sadly it didn't work. Anyone help on this please?
>>> TIA.
>>
>> In what way didn't it work?
>> The suggestions are correct, so you need to tell us what happened.
>
> The picture is spoilt by numerous thin lines, similar
> to a finger print or lines on an OS map, but mostly in
> a North/South direction.

That sounds like moire patterns, a clash between the pixels of the tv
screen and the pixels of the camera sensor. Were you using a low
resolution such as 1024x768? If so I would try using a high resolution and
then downsize the image to TV resolution afterwards.

It may be worth blurring the image before resizing to help suppress
artefacts. Eg. a digital tv picture has a resolution of 1024 x 576 (if we
assume square pixels), if you shot at a resolution that was say 3072 pixels
wide and applied a radius-1 blur (either precisely in photoshop or by eye
in a program like Irfanview) then you still have 1536 pixels of detail (in
other words more than enough) but when you downsize to the final 1024
pixels wide (or whatever size you choose) you will be less likely to get
moire patterns. This strategy is basically the same as the one that the
anti-aliasing filter in a camera uses.

"Gordon Freeman" wrote in message
> "Bertie Doe" <(E-Mail Removed)> wrote:
>
>>
>> "Willy Eckerslyke" < wrote in message >>> Bertie Doe
>> wrote:
>>>> Hallo. I have an EOS 350 and a Sky box, I've been
>>>> trying to get some images from the tv. Trying to
>>>> get rid of those vertical lines you get on the
>>>> photo. Using google, the suggestions I got were :
>>>> ~ don't use flash
>>>> ~ try and get speed below 1/25th
>>>> ~ use a tripod.
>>>>
>>>> Sadly it didn't work. Anyone help on this please?
>>>> TIA.
>>>
>>> In what way didn't it work?
>>> The suggestions are correct, so you need to tell us
>>> what happened.
>>
>> The picture is spoilt by numerous thin lines,
>> similar to a finger print or lines on an OS map, but
>> mostly in a North/South direction.
>
> That sounds like moire patterns, a clash between the
> pixels of the tv screen and the pixels of the camera
> sensor. Were you using a low resolution such as
> 1024x768? If so I would try using a high resolution
> and then downsize the image to TV resolution
> afterwards.
> It may be worth blurring the image before resizing to
> help suppress artefacts. Eg. a digital tv picture has
> a resolution of 1024 x 576 (if we assume square
> pixels), if you shot at a resolution that was say
> 3072 pixels wide and applied a radius-1 blur (either
> precisely in photoshop or by eye in a program like
> Irfanview) then you still have 1536 pixels of detail
> (in other words more than enough) but when you
> downsize to the final 1024 pixels wide (or whatever
> size you choose) you will be less likely to get moire
> patterns. This strategy is basically the same as the
> one that the anti-aliasing filter in a camera uses.

Higher resolution Gordon, but blurring did help a
little.


"Garry Douglas" < wrote in message
>> I would have thought that you would be more likely
>> to get horizontal
>> lines from a TV pic. As you say above - a shutter
>> speed of slower than
>> 1/25 - ideally longer if the scene on the screen is
>> not fast moving -
>> maybe a 10th of a second so that several scans are
>> completed to avoid the
>> darker/brighter lines.
>
> And if the action on screen is fast moving but you
> are watching a recording (or have a clever HDR that
> let's you pause live action) pause the picture. The
> quality of the paused image on a Sky Plus or Freeview
> HDR box is very good.
>
> If you are still seeing the lines do a series of
> shots at different shutter speeds and find the
> fastest speed that doesn't produce the lines.
>

Thanks Garry, I should have used the freeze-frame on
the Sky digi-box, I'd forgotten it had a couple of hard
drives. It did the trick. Strangely, the optimum speed
was 1/50th.
Thanks all.

..

On Mon, 26 Oct 2009 22:32:26 +0000, Garry Douglas wrote:

> "Bertie Doe" <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed)...
>> "Gordon Freeman" wrote in message
>>> "Bertie Doe" <(E-Mail Removed)> wrote:
>>>
>>>
>>>> "Willy Eckerslyke" < wrote in message >>> Bertie Doe wrote:
>>>>>> Hallo. I have an EOS 350 and a Sky box, I've been trying to get
>>>>>> some images from the tv. Trying to get rid of those vertical lines
>>>>>> you get on the photo. Using google, the suggestions I got were : ~
>>>>>> don't use flash
>>>>>> ~ try and get speed below 1/25th
>>>>>> ~ use a tripod.
>>>>>>
>>>>>> Sadly it didn't work. Anyone help on this please? TIA.
>>>>>
>>>>> In what way didn't it work?
>>>>> The suggestions are correct, so you need to tell us what happened.
>>>>
>>>> The picture is spoilt by numerous thin lines, similar to a finger
>>>> print or lines on an OS map, but mostly in a North/South direction.
>>>
>>> That sounds like moire patterns, a clash between the pixels of the tv
>>> screen and the pixels of the camera sensor. Were you using a low
>>> resolution such as 1024x768? If so I would try using a high resolution
>>> and then downsize the image to TV resolution afterwards. It may be
>>> worth blurring the image before resizing to help suppress artefacts.
>>> Eg. a digital tv picture has a resolution of 1024 x 576 (if we assume
>>> square pixels), if you shot at a resolution that was say 3072 pixels
>>> wide and applied a radius-1 blur (either precisely in photoshop or by
>>> eye in a program like Irfanview) then you still have 1536 pixels of
>>> detail (in other words more than enough) but when you downsize to the
>>> final 1024 pixels wide (or whatever size you choose) you will be less
>>> likely to get moire patterns. This strategy is basically the same as
>>> the one that the anti-aliasing filter in a camera uses.
>>
>> Higher resolution Gordon, but blurring did help a little.
>>
>>
>> "Garry Douglas" < wrote in message
>>>> I would have thought that you would be more likely to get horizontal
>>>> lines from a TV pic. As you say above - a shutter speed of slower
>>>> than 1/25 - ideally longer if the scene on the screen is not fast
>>>> moving - maybe a 10th of a second so that several scans are completed
>>>> to avoid the
>>>> darker/brighter lines.
>>>
>>> And if the action on screen is fast moving but you are watching a
>>> recording (or have a clever HDR that let's you pause live action)
>>> pause the picture. The quality of the paused image on a Sky Plus or
>>> Freeview HDR box is very good.
>>>
>>> If you are still seeing the lines do a series of shots at different
>>> shutter speeds and find the fastest speed that doesn't produce the
>>> lines.
>>>
>>>
>> Thanks Garry, I should have used the freeze-frame on the Sky digi-box,
>> I'd forgotten it had a couple of hard drives. It did the trick.
>> Strangely, the optimum speed was 1/50th.
>> Thanks all.
>
> I did a series of tests with a 350D and a Freeview digital tuner and
> 1/50th produced the best results for me too although I didn't pause the
> picture.

<Chucks in lighted fuse>

At 1/50th you are just capturing one field - on a standard UK TV picture
it's an interlaced display - so half the lines are doen in a 50th of a
second, then the other half - so you've captured only about 300
horizontal lines of detail.

It's probably fine though :-)

"Simes" wrote in message
>
> <Chucks in lighted fuse>
>
> At 1/50th you are just capturing one field - on a
> standard UK TV picture
> it's an interlaced display - so half the lines are
> doen in a 50th of a
> second, then the other half - so you've captured only
> about 300
> horizontal lines of detail.
>
> It's probably fine though :-)

This sequence was at 1/50th
http://www.flickr.com/photos/79133573@N00/tags/adverts/

Thin lines at 1/20th and dark horizontal bar at 1/125th
sec.
http://www.flickr.com/photos/7913357...7622552680591/

Bertie Doe <(E-Mail Removed)> was inspired to say
>
>"Simes" wrote in message
>>
>> <Chucks in lighted fuse>
>>
>> At 1/50th you are just capturing one field - on a standard UK TV
>>picture
>> it's an interlaced display - so half the lines are doen in a 50th of
>>a
>> second, then the other half - so you've captured only about 300
>> horizontal lines of detail.
>>
>> It's probably fine though :-)
>
>This sequence was at 1/50th
>http://www.flickr.com/photos/79133573@N00/tags/adverts/
>
>Thin lines at 1/20th and dark horizontal bar at 1/125th sec.
>http://www.flickr.com/photos/7913357...7622552680591/
>
Your point?

You've captured one-half raster at 1/50, and it's fine. 1/25 would have
given you better clarity, but there may be differences between the two
half rasters (if there's movement on screen etc.)

The 1/125th image merely show the lack of persistence of the screen - so
you've got about 40% bright, another 30% fading and 30%dark.

Mike
--
Michael J Davis

Now with added pictures on http://www.flickr.com/photos/watchman

<><
I have a photographic memory;
but then I forget to load the film
<><

On Tue, 27 Oct 2009 21:10:56 +0000, Bertie Doe wrote:

> "Simes" wrote in message
>>
>> <Chucks in lighted fuse>
>>
>> At 1/50th you are just capturing one field - on a standard UK TV
>> picture
>> it's an interlaced display - so half the lines are doen in a 50th of a
>> second, then the other half - so you've captured only about 300
>> horizontal lines of detail.
>>
>> It's probably fine though :-)
>
> This sequence was at 1/50th
> http://www.flickr.com/photos/79133573@N00/tags/adverts/
>
> Thin lines at 1/20th and dark horizontal bar at 1/125th sec.
> http://www.flickr.com/photos/7913357...7622552680591/

You'd expect this at 1/125 as you are only exposing for a tiny fraction
of the time it takes the scanning dot on the TV to travel the height of
the screen.

Have you any at 1/25th?