Flash Card Capacity Changes Based on ISO Setting
Tom from WI
capacity of my flash card changes if I change the ISO setting. For example,
at ISO 100, the camera readout says I have room for 287 pictures (on my 1GB
flash card). At ISO 1600, the camera says I have room for 232 pictures. The
estimated capacity changes at each of the ISO setting as follows: ISO 100 -
287 pictures; 200 - 270; 400 - 255; 800 - 241 and 1600 - 232.
Obviously the ISO 1600 setting results in a larger file than ISO 100, but I
am curious as to why the capacity isn't the same for all ISO settings.
Any ideas?
Tom
Jeff R.
"Tom from WI" <not_read...@no-name-isp.us> wrote in message
news:2_hii.2239$rL1....@newssvr19.news.prodigy.net...
Noise is "expensive" (in terms of space) to save.
I'm amazed that the camera's firmware acknowledges this in advance.
--
Jeff R.
DoN. Nichols
Just a guess -- as I don't have a Canon -- my experience is
with the Nikon D70. And this does not seem to do that.
But as you change the ISO, the amount of noise will change
somewhat, and if you are in a JPEG mode instead of in RAW (or if there
is compression used with RAW as well), the amount of compression
possible will vary with the noise level.
So -- I suspect that the camera bases the estimate of FC
capacity on the expected compressibility of the file. Nikon simply
makes a safely large estimate of file size, and refines the estimate of
capacity as it acquires more images on the card -- so you almost
*always* get more images than its initial estimate.
I hope that this helps,
DoN.
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Paul Furman
More noise at high ISO just looks like more detail to a computer.
--
Paul Furman Photography
http://www.edgehill.net/1
Bay Natives Nursery
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Somebody
compression means that it can't compress as much. That is why some programs
like Photoshop in their save for web option have a blur slider. If you
smooth out your image tones so that they are closer to each other (less
detail/noise, etc.) jpg is able to get a higher amount of compression making
a smaller file.
Like others I am surprised that the camera indicates this. However, you also
need to keep in mind that since the camera can't see the future the actual
number of shots you get on your card could be more or less than what the
camera indicates and that again is because each image will compress
differently. The same holds true for formats like RAW that use a lossless
compression. An almost black image will compress far better than one that is
loaded with fine details or noise.
Somebody!
Tom from WI
quality JPG) was as follows:
ISO 100 - 2029KB, 200 - 2381, 400 - 2963, 800 - 3477, 1600 - 3786
I took the same (roughly) picture at the 5 ISO sppeds, saving them as RAW
files. The file sizes were:
ISO 100 - 6701KB, 200 - 6675, 400 - 6920, 800 - 7300, 1600 - 7783.
With the camera set to record in RAW mode, again the different ISOs give
different estimated storage capacities:
ISO 100 - 115 Pictures, 200 - 113, 400 - 110, 800 - 106, 1600 - 99
As stated before, capacity is based on my 1GB flash card.
I was surprised that the RAW files also varied.
Tom
"DoN. Nichols" <dnic...@d-and-d.com> wrote in message
news:f6cbc...@news1.newsguy.com...
achilleas...@yahoo.co.uk
wrote:
> I was surprised that the RAW files also varied.
They are losslessly compressed, so anything such as noise, which
doesn't compress (ie random) will obviously also increase the
resulting size.
Robert Coe
: It is the noise. As the ISO goes up so does the noise. Noise in JPG
Even ignoring noise, a higher ISO setting should produce more detail and
therefore a larger image file. That assumes, of course, that you're using the
higher ISO because of low light. Under light strong enough to cause gross
overexposure, higher ISO settings might actually lead (through loss of detail)
to smaller files. But it's reasonable for the camera manufacturer to assume
that either you or the camera will be smart enough not to let that happen and
that higher ISO will result in larger files.
Bob
Clive
a 720 images available no matter what ISO I set (80-800)
Clive
DoN. Nichols
[ ... ]
> I was surprised that the RAW files also varied.
That suggests that this camera, at least, does some compression
of RAW images (hopefully a lossless compression). (I forget what camera
we were talking about.)
The Nikon D70 does not do any compression of its RAW, but I
understand that the D200 offers the choice of lossless compression or
none with RAW files.
Enjoy,
Paul Furman
> According to Tom from WI <not_read...@no-name-isp.us>:
>
>>I took the same (roughly) picture at the 5 ISO speeds, the file size (Finest
>
>>I was surprised that the RAW files also varied.
>
> That suggests that this camera, at least, does some compression
> of RAW images (hopefully a lossless compression). (I forget what camera
> we were talking about.)
>
> The Nikon D70 does not do any compression of its RAW, but I
> understand that the D200 offers the choice of lossless compression or
> none with RAW files.
My understanding (perhaps mistaken) is that they all do some raw
lossless compression and the D70 had the same lossy highlight
compression which is what prompted them to offer completely lossless
compression on the D200 but in fact the loss is completely trivial
except perhaps for some very scientific purposes, even then I doubt
there's any real impact.
DoN. Nichols
> DoN. Nichols wrote:
[ ... ]
> > The Nikon D70 does not do any compression of its RAW, but I
> > understand that the D200 offers the choice of lossless compression or
> > none with RAW files.
>
> My understanding (perhaps mistaken) is that they all do some raw
> lossless compression and the D70 had the same lossy highlight
> compression which is what prompted them to offer completely lossless
> compression on the D200 but in fact the loss is completely trivial
> except perhaps for some very scientific purposes, even then I doubt
> there's any real impact.
You could easily be right. I have no magic pipeline into the
format of the .NEF files (though I guess that I could dig it out from
the ton of source code in dcraw -- but it is rather convoluted. :-)