sRGB vs AdobeRGB

I'd appreciate some guidance on this.
Depending on what I read it seems that there is not one setting that will cover all eventualities.

The two things I do most with my photos are (1) post them on my website in galleries and safari diaries (2) have them printed onto canvas by a professional lab for sale as limited edition prints.

which setting should I use in my camera?
I have tried both and, to be honest, I struggle to see the difference.

"which setting should I use in my camera?"

Assuming you're shooting in RAW, the in-camera setting is meaningless. This setting is only relevant to JPEG image files. You choose the color space in your RAW converter. I always work in the largest color space possible (ProPhoto RGB) and save master files in that space. Only then will I convert to a narrower gamut color space such as ARGB and/or sRGB. If your lab's printer will work with ARGB (ask them), then you probably should choose that color space for your print file for the wider color gamut, while files for Web viewing generally work best in sRGB color space since many Web browsers are not color managed and you also have no control over what viewers with non-calibrated monitors will perceive your images.
In short, I always capture and 'develop' images with the largest amount of information possible because I can use less information down the line should I choose. I cannot gain that information back if I work with more truncated files.
You can learn more and see some color gamut comparison charts with this simple tutorial

Thanks John.
I had a look at the article but it's pretty technical (to me at least).
If I understand you right: basically I can leave the decision until it comes time to convert my RAW file and then choose whichever one is appropriate for my specific output whilst retaining my original RAW file.

That's correct, although as I noted I always choose the color space with the widest gamut (or range) to work with in the RAW converter and then use my image editor to change that space for print or Web files. In Photoshop, you would use Edit->Convert to Profile to achieve that task.

I agree with John. Start with a wide-gamut color space for your 'master file'. You can then change the color space depending upon the output. My master files use Adobe RGB, and I use sRGB for Web images and Adobe RGB for printing.

One caution is is in order, though, and that relates to the color space your monitor is capable of displaying. Most consumer-grade monitors today will easily display the full gamut of colors in sRGB, but cannot display some colors in wider spaces such as Adobe RGB or Prophoto. Unless one uses a wide-gamut monitor, and the images have colors outside what the monitor will display, you may get out-of-gamut warnings in Photo Shop. If you have out-of-gamut colors and then convert to (say) sRGB, the conversion will attempt to map those colors as closely as it can, and the results may not be pleasing.

Now, this may seem academic, and may not affect you to any great degree, but it's something to be aware of, especially for printing.

--P

There's 3 main case figures:

1- Convertion and Master Files
Use ProPhoto RGB for those because most cameras capture more colors than Adobe RGB can display. As an aside, Adobe RGB is what I call an 'accidental color space.' It exists because Adobe needed a color space that was theirs and so they created Adobe RGB. It is the default color space in Photoshop and Lightroom because it is owned by Adobe, not because it is the best or the widest color space.

2 - Prints
Send the print file to your printer in ProPhoto, 16 bit and have Photoshop or the Rip (I use Image Print) convert the file to the printer profile.

3 - Web:
When you export for the web, use the 'save for web' command in Photoshop and convert to sRGB. sRGB is the web's color space and is basically only necessary when displaying photos on the web.

A couple of you have referred to ProPhoto RGB. I've not come across this,what is it?

ProPhoto RGB is a larger color space than either ARGB or sRGB. Currently, no monitors or printers can reproduce such a large color gamut, The reason for choosing it is that, similar to working with 16 bit RAW images, this color space uses the maximum amount of information from the camera sensor. Sometime in the future, we may see monitors and/or printers that can incorporate all of the colors within the PPRGB color space. When that day occurs, your master files in that color space will be ready to take full advantage of the technology.

Thanks John.
I've just upgraded my version of Capture NX to the most recent available and it still doesn't offer me the option of ProPhoto RGB colour space.
Which program could I use for RAW conversion that would offer me ProPhoto?

To my knowledge all raw converters do offer ProPhoto as choice of color space. If ProPhoto is not in your profile library, just add it manually. ProPhoto is available free.

The default color space in LightRoom is ProPhoto. I recommend using ProPhoto there and setting the default color space in Photoshop to ProPhoto for exactly the reasons John outlined above. There will be a day when we can take full advantage of this very wide color space.

Everyone has provided good feedback that accords with my own understanding of color spaces and the "best" approaches to preparing images for the print and web. I have to say, however, that one of your initial remarks (i.e., "I struggle to see the difference" between sRGB and AdobeRGB) is also in line with my own experience. I have a wide-gamut monitor that is supposed to display 97% or so of the Adobe RGB color space, but it's not often that I notice much of a difference when I convert from AdobeRGB to sRGB...or from ProPhotoRGB to sRGB. When I do, it seems that it's the reds, oranges, and pinks that seem to be the most affected.

Long story short, if you don't see that much of a difference, often that's because there isn't one.

Martin,
You can download a ProPhoto profile included in a zip file with other color space profiles here.

Long story short, if you don't see that much of a difference, often that's because there isn't one.

To add to that information, if your image is in AdobeRGB, but only contains colors that exist in sRGB, then a good conversion from ARGB to sRGB might show zero difference. (It's dependent on rendering intent chosen and the algorithms your software uses.)

However, if your image has a lot of colors that exist in AdobeRGB (which would most likely show up in very saturated greens) then a conversion to sRGB will definitely mute those colors.

Note that it also depends on what your monitor can display, as at the edges of the color gamuts that we're talking about, you can definitely have colors in your image that can't be properly shown on the screen.

Thank you all for your assistance. Admittedly some of it went over my head - but it has helped immensely.
I now have the ProPhoto profile (thanks Alain) and I will wait in anticipation for the day when I can see all those extra colours.

" I will wait in anticipation for the day when I can see all those extra colours."

As noted, that may be some time in the distant future.