On 24 Sep 2004 at 14:33, Jack Davis wrote:

> I'm curious about all things photographic including
> digital. Since I own nine 35mm Pentax lenses, seems
> logical to check out the *ist D. While several have
> been playing with the phrase; "*ist D..what a
> wonderful camera", I've also noted the many serious
> praises.
> Please help me understand what I read under the (more
> info) Specification tab on the B&H site: 
> 10D: Raw+Large=8.0MB Fine.             
> 20D: Raw+jpeg(Large)=12.3MB.
> *ist D: Large(Raw)=10.5MB (Tiff)=18.1MB
> All note as "excluding memory".
> The only one which seems to track with its sensor is
> the 10D.
> Trick wording? Meaningful? ...anyone?

Hi Jack,

These file sizes are not really meaningful, beyond an indication of how many 
shots you can expect to cram onto your chosen storage media. 

RAW files in their most basic form consist of a transcription of the RAW values 
corresponding to each pixel in the array, some of these are image forming and 
some are not. Secondly the bit depth of the ADC may be 12 bits but the RAW data 
may be padded (with zeros) to provide a 2 byte word or 16 bits per pixel, 
obviously these extra 4 bits per pixel are redundant but it still increases the 
RAW file size. 

On top of this some RAW file formats are stored uncompressed, some are 
compressed, most also contain EXIF information which can vary between camera 
models and also some (like the *ist D RAW files) can include an embedded JPG 
file.

Most cameras offer similar capabilities WRT noise and exposure latitude and 
from my experience far more differences will be seen between the various post 
processing methods. Generally the in camera processing (TIFF & JPEG) output 
really is little indication of the information that can be extracted from most 
camera RAW files in post processing.

> How does the *ist D's Dynamic Range compare?

The capture latitude of the *ist D is very similar to most other cameras of the 
same age (better than most slide film but poorer than the most forgiving colour 
neg film) but you won't really get to see what it can do if you don't shoot RAW 
and use a good post processing tool like PS CS. The output differences between 
the Pentax Photolab program and PC CS RAW is startling, I didn't realize how 
bad the Pentax program was (and it was much better than the in camera generated 
files).

Cheers,


Rob Studdert
HURSTVILLE AUSTRALIA
Tel +61-2-9554-4110
UTC(GMT)  +10 Hours
[EMAIL PROTECTED]
http://members.ozemail.com.au/~distudio/publications/
Pentax user since 1986, PDMLer since 1998

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