There's a beautiful painting from Edgar Payne, one that I enjoy a lot. I think the main thing I like so much about it is the lively brushwork used and the simplicity used to create such a powerful image. Do you think his painting would've been as powerful if he had painted it exactly as he saw it?
The majority of my work since starting in October 2011 has been created using photo references for the most part [although there have been some paintings, mostly my fantasy genre pieces, that were created completely out of my mind]. On the surface, there's nothing particularly wrong with using references - they can be a great help when you are having trouble rendering a certain object for a scene or for when you may need some inspiration to spark your creativity. The trouble is that most beginners, myself included, don't understand how to properly use them for their work - which in the long run ends up hurting their work and slowing progress, not helping it.
One of the first things you must understand is that almost all of the time, nature will never give you an appealing image. Even most photographers nowadays end up cropping, adjusting colors and settings, and manipulating their pieces after a photo is taken. An image from nature. I would definitely have to manipulate elements in this photo to create an image worth painting.
Art is designed - elements within nature moved around and placed elsewhere, some taken out or inserted, colors improved upon or toned down, value shifted up or down, etc.
From my own experience [of being a beginner], the beginner doesn't design but rather they copy what is in front of them completely whether it's a photograph or en plein air - matching the tones of nature, every branch and leaf, every fence post, cloud and detail. I've been guilty of this numerous times! Of course, matching colors exactly isn't a bad exercise and probably should be done for practice and color-mixing control but don't believe that by copying nature in its entirety will give you a pleasing or even interesting painting.
John Carlson sums it up quite nicely in his book stating "The beginner in painting copies nature in all its literalness. He makes his painting look like the place. Soon he learns to omit the superfluous, grasp the essentials and arrange them into a more powerful and significant whole."
Working from photographs is difficult due to all of the detail found in them and flatness of shapes and colors. You must learn to simplify, as Carlson said - I always wondered as a kid why artists would squint and now I do it myself and find it to be quite useful. And remember, if something doesn't add anything to the overall image, get rid of it - it's as simple as that.
I find myself these days working from value sketches and simplified drawings. These give me more control over my design and make it easier to manipulate what I wish. By using a sketch, it also allows me to freely use color as I'm not concerned with making it match mother nature tone for tone. It allows me to create my own compositions, no longer a slave to what is in front of me.
The thing is - those paintings from your favorite artist that you enjoy so much, the ones that look so believable, were not found in nature as they are on the canvas - they were designed, crafted and created. Sure, they may be based on a particular place but you can believe that things were cut out, moved around and changed for the purpose of creating a beautiful image.
Here's a subtle example of that above - 3 paintings by Scott Christensen. At a quick glance, you will notice that all 3 paintings are of the same place and don't look much different. But upon closer inspection you can begin to see subtle differences between them, particularly between the bottom image and the top 2. He gives more prominence to the trees in the bottom image - the cropping is different and also the height of the mountains in the distance - and even the background trees in the distance are difference sizes between all three.
I have heard that you should at least be painting for 10 years before painting from a photo - and now I understand why. After spending my first 2 years of painting using reference photos for everything, I can tell you that they did not help me to improve or create appealing images. I did not know how to manipulate them while painting from them.
My latest works have been created using photos initially but only for the purpose of getting the subject and perspective correct in my sketches. I then begin to manipulate the elements [adding, subtracting, moving] through many thumbnail sketches I create. After many small sketches to determine the overall design, I move to a larger, more finalized sketch. In this stage I start thinking about how I felt when I was at this particular place and what I remember - this helps me with color choices and emotion of the painting.
In the future, I plan on working more from memory, and also from life, than from using any photos. Free yourself from the slavery of the photo reference!