Question: Is the color something that is added by the photographer or does it really look red in the telescope I wonder?
It would just be a shift in wavelength if they did, wouldn’t it?
Red or pink is the typical color of emission nebula, which this is. With a big enough telescope you could begin to see color, but to be enhanced like this you need a time exposure. Additionally, this is no doubt a composite of 3 photos using red/green/blue filters, which really brings out the color because these are the peak wavelengths seen by the human eye.
Under VERY dark skies, with a large scope and really good eyesight, you MIGHT see color in this.
When I was younger, I could regularly see reds (and somenights blues) in the Orion Nebula. But now, even in larger scopes, it’s all gray/green.
Most light through a telescope isn’t bright enough to activate the color sensors in your eye. And if it is, then your night vision is shot for a bit.
M17 IS bright enough to see through a small telescope in the city. It’s in the Astronomical League’s Urban list.