More RAW pics with the DRebel russian firmware

I have read that with the russian firmware hack for the DRebel, it is possible to take more raw pics than with the canon firmware. I'm just wondering how is this possible ? Are they some information that the russian firmware does not record

Yacine.

There is a feature in the firmware hack that allows you to change the type of JPEG saved and embeded in the raw file. By Default canon has set it to save a RAW File, but with also a Large Jpeg embeded in it, making the files roughly 6MB or so in side, the firmware allows you to change the size of the jpeg saved, most people never even use the embeded jpeg, so when you set to Raw+Small , you get a bit of extra room to save the files. The files them become on adverage 4.5MB each or so.

oh I see, Thanks.

I don't think you are trying to claim that Raw+Small will yield a 4.5MB file, are you?

Raw+anything will be at least 6MB.

Raw alone gives me at least 6MB. Sometimes 6-9MB.

Please clarify.

---Bob Gross---

Actually , it gives me anywhere from 4.5MB to 7.5MB at the most for all my .CRW files, the sizes were somewhat larger when set with +Large JPG. My average CRW file is about 5MB

Average CRW file is about 5MB?

Very interesting!

Somebody explain how that works, because on my D60, the CRW file (Raw only, no JPEG) is 6-9MB. Most of these cameras have the same sensor size (6 Megapixels).

Is this for an ordinary (random) subject, or is this for some plain background, or test pattern? Does the 5MB figure vary with ISO?

In general, on mine, the higher the ISO, the more the color noise, so the less-compressible the CRW file is, so the closer to 9MB it is.

---Bob Gross---

each picture has a certain amount of information in it (entropy). an uncompressed raw file does include this information plus redundant parts.

the goal of lossless compression is now to extract the entropy, so the total size decreases.

now, with high ISO, the noise adds more information to the picture. even if this is false information (it was not in front of the lens, but the sensor that created it - random noise). because random signals have the highest possible entropy rate, these raw files do not compress well - as there is simply more information contained in them.

OTOH, if you take a picture witht the cap on the lens (or even a lot of black areas, or white - whatever) - you will get a relatively small raw file (the same with JPEG), because there is almost no information in this picture.

hope this makes sense.

regards
nicola

I've just checked the only set of RAW files I have on my hard disc (I can't be bothered to go and dig out any DVDs to check them). The largest RAW file is 5.8MB and the smallest 4.9MB. I would say (without doing the arithmetic but just taking a visual feel for the file size distribution) that the "average" size was around 5.2MB.

The shots were of racing cars taken at Silverstone circuit using a 10D. ISO was 400 for all shots. The camera was set to RAW (small JPEG).

So far, you have been discussing the size of RAW+JPEG within the DRebel, and you are mentioning sizes around 5MB.

On my D60 (similar sensor), the size of RAW alone is never less than about 6MB, unless I shoot something highly compressible, like the inside of a lens cap.

Interesting.

I would have thought that the RAW non-lossy compression would be very similar between the DRebel and the D60. Now, it seems that they are not.

Hmmm.

---Bob Gross---

Aside from the fascinating RAW size versus entropy discussion, I'd like to point out that the 300D default is RAW+Medium JPEG, not large, as was stated previously.

I'm interested in the hack mainly because I'd like to actually get full-size JPEGs embedded in my RAW. If I nail a few photos with proper exposure and color balance, I may consider it redundant to develop the RAW at all.

This, I'm sure would please those that claim that they always shoot in JPEG, because they get it right (most) every time, thus not invoking a RAW post-processing penalty if not needed (but keep that 'ace-in-the-hole' for those times that their infallable mental metering system breaks down )

Bob just checked a bunch of 10D RAWs.. I have the smallest joeg embedded.. and the files are Averadging 5.5 MB

Maybe with the 10D Canon imcreased the lossless compression?

Who did?

Mere speculation.

---Bob Gross---

Capture one raw converter

I'm by no means an expert but it would seem that there is in deed a difference between the way each of these particulaly the 300d and 10d cameras write the raw files to the cards. Why? Well if Capture one software are able to say and imbed into their software a different generic profile for each and in fact every camera then surely the reason is each camera writes to the cards slightly differently? Well it might be the reason.

Unclear.

Capture One doesn't have anything at all to do with the size of the Raw file that a camera writes.

---Bob Gross---

The only few files that I could find (I've got a 10D) and go below 5,000.000 bytes are either really dark, or really bright or somwhere inbetween but with no detail, like pure sky or fog.

The smallest crw shot has 4,321.140 bytes, interestingly the largest file that I have is shot in ISO 100 and has 8,514.954 bytes. The estimated average is a bit above 6,000.000 bytes.

Please note that 6,000.000 bytes does not equal 6 megabytes. Perhaps some people have made mistakes this way, so there are bigger discrepancies...

I think it all depends on what you shoot and how you shoot it, only a head to head comparison could prove if there actually are differences between models.