I was born myopic. Really very short sighted indeed. Without spectacles, I can focus to about 9" away from my face, and everything beyond that turns into an Impressionist blur.
Which is absolutely brilliant.
Because, as a painter, it's the best of all possible worlds. When I peer over the top of my specs, all I can see is big, soft edged shapes and average colour values.
When I slide them back up my nose, I can see pin sharp detail in depth.
Which is exactly the best combination a painter could ask for.
Whenever a drawing or painting threatens to get bitty and piecemeal, just take off the specs and immediately see the big picture. And pretty much nothing but.
It applies to painting from photographs too. I've talked elsewhere about working from photographs, but the problems I listed - particularly excess detail - can be overcome by the simplest means.
Turn off your camera autofocus, and using the focus ring on the lens, just blur the picture slightly. Take a sharp picture, and a fuzzy, out of focus one. Or just run your sharp picture through a blur filter in GIMP. Go on. It's free. All the functions of Photoshop at the price point everybody loves.
Detail is a weird thing to deal with, and a snare to get hung up on if you're not careful. If you're a photo-realist, who takes three months to paint a large canvas, squaring up a photograph and painstakingly copying it, detail is everything.
If you're an impressionist, trying to catch a fleeting light effect, detail is a trap.
Most figurative painters work somewhere between those two extremes, and constantly run the risk of getting snarled up in a tight, fussy interpretation of what they can see. It's something that lends itself to overthinking, which will hamper your painting efforts if you let it.
Perhaps the best way to deal with detail is to not consider it as something separate, but as part of the process.
A simple solution is to start with a big brush, and never get too small. If you ever find yourself fiddling with a one hair brush and squinting, you're doing it wrong.
As you gradually work towards smaller and tighter areas, relate your small brushstrokes to the large ones in terms of how you make them. And remember, you can't paint everything, and if you did it would look awful.
Imagine, for example, you're painting some trees. In the foreground, some leaves are hanging above you and 'in shot', as it were. You could paint these one by one insofar as they contribute to your composition. How closely you observe them is up to you, but if you go into so much detail that they take over the whole painting, you've failed. Paint objects as well as they need to be painted for the part they play in the painting as a whole.
And at some point, as they recede into the distance, individual leaves become foliage masses. That tree fifty feet away? Probably best rendered by a well drawn green blob with some subtle edge and mass detail to suggest foliage. That stand of trees in the distance? A tiny blue speck explained by context and well judged tone and value.
Remember that a painting is about big, beautiful shapes. You should be able to judge a painting from across a large room.
On the other hand, if you walk across that room and find the painting gets no clearer, you're entitled to feel somewhat cheated, and a little more detail might well be in order.
You have to strike the balance between the broad picture and the telling detail for a painting to work. I once ruined a landscape painting by working too closely from photographs. If you ever do this, make sure you keep stepping back from close detail work to judge the painting from its proper viewing distance. While detail is necessary, some passages should be broadly handled to provide contrast and give the eye a rest. I ended up painting detail all over the place, which just looks weird.
There's a particular kind of amateur painter who thinks that adding detail can only improve a painting, but they're wrong. Exactitude in painting matters, but it's a different kind of exactitude. A ragged flick of paint, providing it's of the right tone, the right colour, and in the right place, can tell the viewer more than any amount of fussy, nit-picking detail. Context is everything.
What if you're not lucky enough to have been born short sighted?
Squint. When you're face with a big, complex subject, whether it be a landscape or anything else, the first thing to do is to see less of it.
Squint, until you can just make out the big shapes and get a handle on how to tackle your drawing or painting. Start with the general and work towards the particular - and only include as much of the latter as you strictly need.