Going through some of my Iceland Wildlife images from 2014 when I came across this - I didn’t intentionally shoot any landscapes then - barely knew how to use a 600mm lens then 
But obviously got taken away by that beautiful light with some lovely fog as icing!
Up for anything really
Is this a composite: No
Nikon D4s - 600mm
F8, ISO 4000, 1/800sec
any slower shutter speed might have resulted in lesser definition in the fog / low lying clouds ?
I think I prefer the landscape version, Karl. It has some space to give it a sense of size. Nice catch with the light.
Great light Karl, the photo gods rewarded you with these conditions, warm light and foggy, clouds what more could you ask for? Of the two images you have presented, like @David_Bostock I also prefer the horizontal composition for the sense of grandeur it conveys. It makes the mountain feel and look bigger. The noise reduction in the processing of the horizontal also helps.
In the horizontal, there is a bit of haloing along the mountaintop, particularly along the right. When you have high contrast edges like this, your processing of contrast can result in halos. I was recently watching a video by Michael Frye where he suggests removing such halos in Lightroom by using a very small local adjustment brush to paint in negative clarity, negative texture, and negative sharpness to soften edge halos. You might wan tot try that out to see if it helps.
The reddish overall caste makes the image for me in the original.
