Q about Lightroom setting . . .

OK, a few weeks ago I was having problems with Lightroom (conversions), but I just got a brand new computer and things already seem better. I do have one question though . . .

Looking at the preferences, LR has selected "ProPhoto RGB" as my color space (for edits.) I can switch it to plain ole "sRGB", but then it tells me: "The sRGB color space cannot encompass the full range of colors available within Lightroom." Should I just ignore that and switch anyway?

(NOTE: If I keep it "ProPhoto RGB" is says, "16-bit ProPhoto RGB is the recommended choice for best preserving color details from Lightroom.")

Thanks!

All the advice I've ever read, is stick with ProPhoto RGB for editing. If you are planning on printing any of your images you need all the color information you can have before converting to a print profile. Convert to sRGB only when/if you are outputting JPEGs to the web.

I've always been disturbed by that blurb that LR puts there, because it is technically correct but misleading and potentially dangerous. Over and over again I see people using ProPhoto RGB and Adobe RGB inappropriately because they have heard or been told that they are better. Yes, it is true that ProPhoto RGB has a gamut nearly as big as the camera's native capture gamut, but there are at least four things you need to be aware of:
1. Those extra colors mostly don't exist in the real world. They do exist in brightly colored flowers and kids plastic toys and a few other things but the majority of your subjects will have no greater range of colors than can fit into the narrow gamut of sRGB. Ideally, you should use a space whose gamut is only slightly wider than the subject gamut. Using a gamut a lot wider than the subject means that a lot of the space is wasted and as a consequence you actually end up with fewer discrete color tones than you would have had in sRGB. Moreover, if you do not edit ProPhoto RGB in 16 bit depth, you can do your image real damage.
2. Even if you do have those ProPhoto colors present in your subject you won't be able to see them on your monitor, so you will have to be adept at editing according to the histogram and the numerical readout and at understanding what they mean in a wide gamut. To be something like Beethoven composing music even though he was deaf because his brain knew what sounds the written notes represented. Of course, nobody else will see them on their monitors either.
3. Even if you do have those ProPhoto colors present in your subject, you won't be able to print them. High end home inkjets, the kind with 7 to 10 ink colors, can print Adobe RGB and sometimes a bit more. None of them can get close to ProPhoto. As for commercial print labs, their machines have color spaces even smaller than sRGB.
4. At the end of the day, when you have to convert down to sRGB anyways, if you haven't set up your ProPhoto image properly, that conversion can cause a load of highlight clipping and anything you may have gained by editing in ProPhoto will be lost.

ProPhoto RGB has its place and its uses, but using it without understanding why and how is, in my opinion, ill-advised

Kristen, one important thing to bear in mind here is that the Preference you are referring to is only applied to when you are opening an image to edit in another application, such as Photoshop but it could be any app.

Lightroom itself only uses the ProPhoto color space (actually a derivative called "Melissa") internally, meaning that you can do best keeping color space considerations in mind before you do a conversion -- for example, if you are working with bright, saturated colorful flowers or fabrics or something similar (like Elie's toys), you may want to tone those colors down a bit in Lightroom. Then, when you open the file in Photoshop, you can do this in a "tamer" color space -- sRGB is "safe", although many people prefer aRGB if they are preparing an image for printing using a wide gamut monitor and if their system is capable of handling aRGB images without being "messy". But, for "safe" images for general use, like the Web and sharing with family/friends/clients​, sRGB is necessary. So for these uses, have both your Export dialog and your External Editor preferences set to sRGB, and then make sure that a color managed app (Photoshop or DPP) is set to sRGB so that you can have a smooth "pass it on" transition. In time as you learn more about all the complicated "stuff", you will hear people "talking up" an aRGB workflow, but don't rush into things until you really have a grasp on what's going on!

To make matters worse, LR will not give you a clipping warning for sRGB: http://www.getcolorman​aged.com …management/clip​warninglr/

Then again: If you work in ProPhotoRGB and convert to sRGB later, any out of sRGB gamut colors will be clipped as well.

If you want to use ProPhotoRGB, you should use 16bpc as well.
There are a few links in the "Color problems?" sticky on the sRGB-AdobeRGB-ProphotoRGB and 8 vs. 16bpc topic.

tzalman wrote in post #12280075
3. Even if you do have those ProPhoto colors present in your subject, you won't be able to print them. High end home inkjets, the kind with 7 to 10 ink colors, can print Adobe RGB and sometimes a bit more. None of them can get close to ProPhoto. As for commercial print labs, their machines have color spaces even smaller than sRGB.

^^
No commercial photo printing labs even directly use aRGB files. (I periodically publish a 'challenge' on POTN for anyone to identify a photo printer who directly prints from aRGB files, and no one has yet met that challenge!) Most photo print labs will not accept aRGB files, and those that accept aRGB files will first convert them to sRGB before making the print!

Printers who accept aRGB are more typically for offset print tasks (file output with CYMK for quality and registration control reasons during multi-pass printing) like brochures and high quality photo reproduction in books.