Everyone photographs autumn for its color. Take the color away and most of those pictures collapse into gray mush, which is exactly why the season is worth working at.
There is a pull off on every scenic road in New England right now with half a dozen people standing at it, all pointing at the same hillside. The light is flat, the trees are blazing, and the pictures will be fine in color and almost unusable in black and white. That is not bad luck. Red and green foliage sit at nearly the same brightness, so the moment the color is gone they merge into one undifferentiated mass, and no amount of editing pulls them back apart.
The season is still worth photographing. It just asks for different decisions than the ones the postcards are made from.
Shoot against the sky, not against more trees
This is the single most useful change, and it costs nothing. A branch photographed against a bright sky separates cleanly, because sky and foliage are far apart in brightness. The same branch photographed against a hillside of other trees disappears into them, because everything behind it is the same tone.
So get underneath things and look up. Find the tree standing alone at the edge of a field rather than the one in the middle of the woods. Put the subject where the background is something other than more of the subject. If you want to push the sky darker and the separation further, a yellow or orange filter will do it at the moment of capture, which we went through in two filters that monochrome photographers need.
Backlight does the job color used to do
A leaf lit from behind glows. That is not a metaphor, it is physics, and it is the most reliable separation tool the season hands us. Light coming through a leaf makes it brighter than everything around it, which means it stops being one more red shape in a field of red shapes and becomes the brightest thing in the frame. Autumn leaves are thin and translucent in a way summer leaves are not, so they take backlight better than they ever will again.
Practically this means shooting into the sun rather than with it behind you, early or late when it is low enough to come through the canopy rather than down onto it. Walk until the light is in front of you and watch what happens to the same tree you just photographed from the other side.
Then take a stop off
The meter will try to ruin this for you. Pointed at a backlit scene it sees all that brightness, panics, and brings the exposure down just enough to make the glow ordinary, or it does the opposite and opens up to protect the shadows until the leaves blow out to blank white.
What works is deciding that the glow is the subject and exposing for it. Dial in a stop of negative compensation, let the trunks and the ground go dark, and keep the detail inside the lit leaves. The histogram will look wrong, bunched to the left with a spike at the top end, and the picture will look right. We made the general case for this in overexposure, underexposure and the mood in between, and autumn backlight is the clearest example of it we know.
Go out in the rain
Rain solves the contrast problem that dry autumn light creates. Wet pavement turns into a mirror and picks up every bright thing above it. Wet leaves on the ground go dark and glossy, so the pale ones sitting on top of them stand out. Everything gains a specular highlight, and specular highlights are the brightest tone available to us, which gives a frame somewhere to peak.
The hour after the rain stops is better still. The surfaces are still wet, the sky often breaks, and if any low sun gets underneath the cloud you get the backlight and the reflections at the same time. A polarizer is worth carrying here, not to deepen the sky but to control how much glare comes off the wet leaves, because at full strength it turns them dark and rich rather than white and blown.
Then go out in the fog
Mist is the one weather that separates a scene by tone alone, which is exactly the thing autumn color normally does and monochrome cannot. The nearest trees come out dark, the ones behind them lighter, the ones behind those lighter again, until the furthest row is barely there. You get depth without needing a single hue to carry it, and a woodland that was an impenetrable gray tangle on a clear day becomes legible.
Autumn mornings produce this constantly, because the ground is still warm and the air has turned cold. It usually burns off within an hour or two of sunrise, which is the real reason most people never photograph it.
None of these moves are about rescuing a color subject. They are about photographing what autumn actually is underneath the display, which is a season of thin light, wet ground, bare structure arriving and everything being briefly lit from behind. Color shows you the party. Gray shows you what the party is for.