Hi Vinny, because you asked so nicely and your son clearly has an eye for a photograph I will offer my ramblings. They may seem harsh and very small details, but that is the point. It's a good photo so it's worth looking at the details.
Main critique, for me it is overexposed. Some of the highlights in the water have turned to pure white and the midpoint of the image is too bright. I feel looking at the highlights in the water that are nearly white and reading the same colour value, this overexposure was done in camera, and the fact there is no black point. Or, if the RAW file shows no clipping in the highlights there is a chance your son has used the white point clicker on the water somewhere, which caused the overexposure in post. If that is the case it can be rectified easily.
Composition is very good. The only thing I would have done differently is separated the rock in the water at the bottom on the left from the green rock on the river bank but moving the camera to the right a fraction.
White balance is pretty good, it is a hair blue by the numbers and for me personally.
Diffraction or slight camera movement over the 2 second exposure has taken the edge of the sharpness at 100%. I can see why he used f/22 for the water movement, but a lens on a crop camera stopped down beyond f/11 really can start to show diffraction, which ends up as softness throughout. The ways round this are to either accept a shorter exposure and less water movement, or to either use a neutral density filter to reduce the light entering the lens or to shoot the image once at f/11 say for the rocks, then again without moving the camera at f/22 for the water and blend them in Photoshop.
Colour profile, great that he is working in Adobe RGB especially if your monitor/s at home support the wider gamut. However for displaying on the web I would recommend converting to sRGB to allow a more accurate representation of colour on other devices, this will stop the image looking washed out on other peoples devices as the colour space for web browsers is only sRGB. (This may also contribute to the feeling the image is overexposed actually).
I include below the jpeg fro flickr with minor levels adjustments only (and converted to sRGB). black and white points adjusted to equalise the blue channel in line with the red and green. Moved the mid point down to 0.80. This is just a suggestion, that for me gives the image more contrast and the feel of a wooded waterfall more.
vinnyvsonsimage by
Craig Hollis, on Flickr
