'Focal length' is what you're referring to I guess(?) While a 55mm lens on a 35mm (film) camera will cover the same area (or give the same field of view), different focal lengths and different film (or electronic image sensors) sizes give different field of views (or coverage).

I'm not sure what you mean by 'reference photos'. Are these images or renders you make and want to keep as a reference for future work?

I have no idea if either Daz's or Poser's cameras are based on real world optics. I just set them to whatever I feel gives the view I want. I generally use 55mm to start since that's historically a 'normal' view. On a 35mm film camera, a 55mm lens shows the same view as the naked eye (mostly). During the early days of digital, manufacturers gave field of views, or compared them to 35mm cameras. I don't see this much anymore since the pro cameras are pretty much the same size as 35mm film and no one really cares much when using an amateur camera (point and shoot). As a pro I don't bother with numbers anymore. What I see is what I get and that's all I care about. It becomes a factor only for the occasions when I'm doing technical or engineering stuff.

If you're looking for a starting point or want some kind of standard, pick settings that work for you, write them down and go from there.

Does this help or did I miss the point of your question?

Bob