Shooting RAW ?

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The Hat

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Can anyone explain in idiot terms what is meant by shooting RAW, it's advantages and disadvantages ?

I'm after finding out wether it's of use to me,esp as the S95 I'm thinking of getting doesn't have the ability. Do I really need the ability when I dont do much printing at mo.

Cheers

Paul
 
In idiot terms which I understand

Yes think of it as layers of glass. Jpeg is just one sheet and you can only adjust a certain amount on that sheet. In Raw it is like several layers of glass one on top of the other, this allows you to "pull" out one sheet (level) and make adjustments and put it back, if that makes any sense

Realspeed
 
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Basically RAW is like a Digital negative and the shot image can be adjusted in PP for many different things- very useful to shoot in RAW as opposed to JPG :thumbs: as RAW has many advantages

When a digital camera makes an exposure the imaging chip (whether it's CCD or CMOS) records the amount of light that has hit each pixel, or photo site. This is recorded as a voltage level. The camera's analog to digital circuitry now changes this analog voltage signal into a digital representation. Depending on the camera's circuitry either 12 or 14 bits of data are recorded. Incidentally, if the camera records 12 bits of data then each pixel can handle 4,096 brightness levels (2^12), and if 14 bit then it can record 16,384 different brightness levels (2^14). (To my knowledge no current imaging chip records a true 16 bits worth of data).

Of course what happens after you've taken the photograph depends on whether you have the camera set to save images to the memory card as raw files or JPGs.

If you've saved the file in raw mode when it is subsequently loaded into a raw conversion program and then saved to a TIFF or .PSD format file it can be exported in 16 bit mode. The 12 or 14 bits recorded by the camera are then spread over the full 16 bit workspace. If you've saved the file in-camera as a JPG than it is converted by the camera's software to 8 bit mode and you will only ever have 256 brightness levels to work with. SIMPLES ......


Les :thumbs:
 
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The Hat said:
Can anyone explain in idiot terms what is meant by shooting RAW, it's advantages and disadvantages ?

I'm after finding out wether it's of use to me,esp as the S95 I'm thinking of getting doesn't have the ability. Do I really need the ability when I dont do much printing at mo.

Cheers

Paul
Click to expand...

A raw file contains all the information captured by your image sensor.

A jpeg is a file that has processed and compressed this information.

A raw file (from my D700) is around 12Mb, a jpeg would be around 6Mb so the cameras on board computer has processed the raw information and discarded 6Mb (or half) of the data from the image.

I use raw for any serious stuff, and jpeg for holiday / family event snaps.

If you get everything right when taking the photo jpeg is fine, raw gives you a bit more latitude for adjustment in PP.

I take a lot of wild bird images, this can involve a hefty crop of the original image, with shooting raw I know I am still going to have a decent sized file to work with even after cropping.




.
 
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I haven't followed the links above which may well be more helpful but I'd explain as follows.

Consider a black and white image.

Imagine that this image is produced using only 256 shades of grey between fully black and fully white. That probably allows for about 2 or 3 shades to be used for a very bright sky. This is a jpg.

But now imagine that each one of those shades of grey is divided into as many as 256 subdivisions so you have, maybe, 65,000 shades of grey rather than just 256. This is a raw image

Now imagine that you're not quite happy with your slightly overexposed sky and you decide to darken it a bit. If you only have 2 or 3 shades of grey in the sky it will just be large areas of the same shade but with noticeable and ugly steps between the areas and it will have almost no detail. If you have hundreds of shades used in the sky you will be able to do it almost seamlessly.

I'd advise anyone who cares even slightly about the images they take to always shoot raw.
 
The Hat said:
Why does a good camera like an S95 not have this ability
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Because Canon has decided its S95 target buyers don't need it, and are unlikely to use Raw if it was provided anyway, because they don't have the software or the time/skill/inclination to use it. Many professionals only shoot JPEG, because if you get things right in-camera, the output is indistinguishable from a post-processed Raw, and you can still tweak the JPEG quite a lot if needs be.

All images start out as Raw, even in phone-cams, and can't be viewed without processing. Even if you shoot only Raw, the image you see on the camera's LCD is a small JPEG, and all images are finally output and viewed as JPEGs (well, 99.9% of them).

The key difference is that when you choose JPEG, the post processing parameters are decided before you take the picture and applied immediately in-camera, as opposed to being decided and applied afterwards with specialist software on the PC. The result is a dramtically smaller file, which is ready to view and is much faster/easier to manage.

The main reduction in the file size is from the mathematical compression, not the 'loss' of data as such - the pixels are still there. For example, if you have an area of uniform tone such as a clear sky, if that occupies 2m pixels it might be written as 01010101 two million times - a massive string of data half a mile long. That can be reduced to a formula 01x2m, and that cluster of pixels in the image still looks exactly the same. You get the idea.

After the JPEG process, some data is discarded, but only because it's not needed (depending on the JPEG level selected). The difficulty comes if you then want to further modify the JPEG, and find that some aspects of the compressed clusters are locked together - you can change the cluster to make it darker or lighter or more blue, but only as a group. Fortunately, most clusters are only a dozen or so pixels on average, if you've selected JPEG Fine, but of course you can't modify anything that's been discarded. However, you can still do a lot more to a JPEG than some folks think - it's not completely set in stone, far from it, but obviously there's less scope.

Bottom line these days is to shoot both Raw and JPEG, and get the best of both worlds (if you have sotware). It used to be a big decision because memory was expensive and cards were very small, but it's cheap as chips today, eg 8gb for £20 whereas only a few years ago 1gb would cost £100 or more.

Edit: hang on a minute, Canon S95 does Raw!
 
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When you look at a RAW file, you're not actually seeing the RAW data. You can't, because it's a meaningless series of ones and noughts, arranged differently by each manufacturer. Lightroom, and every other piece of photo software, interprets the data to produce a JPG or TIFF image on your screen, often using the camera settings for sharpening, tone curve, colour balance and the like. This isn't the finished picture, it's just that Lightroom, Photoshop or whatever has to do something to make a picture from the RAW, so it does that.

If you shoot in JPG, you do that something in the camera, using the various shooting menu options (vivid, portrait, landscape, extra sharpening etc.) and the result is not exactly fixed, but there is only a limited amount of adjustment available to you if you don't like the finished result.

Shooting in RAW brings the well, raw, data into Lightroom (which makes a viewable picture from it as detailed above), but you are free to perform as much processing as you like yourself, one parameter at a time. When you perform these adjustments, and this is a really important bit, you do not change the original RAW data at all. You are producing a JPG to order for a particular purpose. You can make one version for printing, a different one for the web, yet another for a T-shirt and so on.

For an analogy, if you buy a piece of music in MP3 format you can change the volume, turn up the treble and bass, change the stereo panning and that's about it. All the mixing has been done in the studio. That's a JPG produced in camera.

If you go to the studio and get hold of the individual tracks for each instrument you could make your own mix, sounding exactly the way you want it, and leave the original recordings untouched for a remix later on. That's RAW.
 
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Why is it that i cannot see a dif between a RAW and a Jpeg? I have seen some on here and just cant tell the difference.
 
cam1986 said:
Why is it that i cannot see a dif between a RAW and a Jpeg? I have seen some on here and just cant tell the difference.
Click to expand...

Because the one's you see on here have been converted to jpg and once that's happened you can't tell the difference. The reason for doing it like that is you can manipulate it much more BEFORE you convert it into jpg.


Have a read of some of the links posted, it should explain everything.
 
But if i can't see a difference whats the point in using RAW if they are both going to turn out the same or is it that lots more manipulation in RAW can produce more varied results?
 
cam1986 said:
or is it that lots more manipulation in RAW can produce more varied results?
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This.

For me one of the main benefits is highlight recovery which means if you over expose you can recover the blown bits much better than with jpg.

Read the links.
 
You haven't seen the RAW picture, you've seen a JPG produced from the RAW data.
 
cam1986 said:
But if i can't see a difference whats the point in using RAW if they are both going to turn out the same or is it that lots more manipulation in RAW can produce more varied results?
Click to expand...

Think of it as painting by numbers. Shoot jpeg and it's like using putting the colours on the numbers. Shoot RAW and your can have the same painting, or slightly, or massively different using your own paints and no numbers to follow, but still have the same scene though.:)
 
There is an excellent series of videos about RAW here.

It is sometimes easier for people to watch videos describing the subject rather than explanations and analogy's. ;)
 
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