There is so much good material in this forum concerning the merits of employing ProPhoto RGB, but a search on my part has failed (for me) to answer the following query, which I will preface with a quote from Vincente Versace's 2011 update of his book "Welcome to Oz 2.0."
His page eight, with a heading "Setting Up Photoshop for a Non-Destructive Workflow," discusses the relative merits of ProPhoto, sRGB, and Adobe RGB.
He then has a separate "NOTE" on the page which reads as follows"
"Once you capture in or convert into a smaller color space, all you have are the colors of that space. So if you have been converting your sRGB captured files into ProPhoto RGB thinking that you have maximized the gamut of color, what you really have done is similar to pouring a quart of water into a gallon container; it is still only a quart of water."
The use of the words "capture' and "captured' in the above quote are what concern (and puzzle) me. My cameras only have the options of designating as color space sRGB and Adobe RGB. Does this therefore mean, according to my understanding of Versace's NOTE, that any attempted use of ProPhoto RGB in my Lightroom or Photoshop processing is of no real benefit because of the inherent limitations of my cameras' color "captures" in either sRGB or Adobe RGB?
Is this really so? Or am I -- one again! -- confused.