Start by seeing in tones, not colours
Black and white photography removes colour, so everything the picture says has to be said with brightness. Your job is to look at a scene and ask where the bright parts, the dark parts and the middle greys sit.
A red door and a green hedge can look completely different in colour and almost identical in black and white, because they are about the same brightness. If two things you want to separate are the same tone, the picture will feel muddy. Look for differences in light and dark, not differences in hue.
A useful habit is to squint at the scene. Squinting blurs detail and colour and leaves you with shapes of light and shade. If the scene still reads clearly when you squint, it will probably work in mono.
Light and contrast do the heavy lifting
Without colour, light becomes the subject. Hard side light from a low sun carves faces and walls into bright and dark shapes. Window light gives a softer gradient across a face. Overcast skies give gentle, even tones that suit quiet, moody pictures.
Contrast is the gap between your darkest and lightest areas. High contrast feels graphic and bold. Low contrast feels soft and calm. Neither is better. Pick the one that fits the mood of the scene, and avoid the middle zone where everything is a similar grey.
On iPhone, tap the screen to set focus and exposure, then drag the sun icon down slightly. Protecting the bright areas usually gives a better black and white photo than letting them burn out to plain white. Shadows can be lifted or deepened later.
Subjects that work well
Portraits are the classic choice. Without colour, attention goes to the eyes, the shape of the face and the expression. Skin tones also become more forgiving, because uneven colour disappears.
Architecture and street scenes suit mono because they are full of lines, shadows and repeated shapes. Look for a strip of light on a pavement, a staircase, a window casting a pattern on a wall.
Textures also reward black and white: weathered wood, rain on glass, rough stone, fabric. And scenes with messy or clashing colour, such as a busy market or a room with bright plastic everywhere, often become calmer and cleaner once the colour is gone.
When to choose black and white
Choose it when colour is a distraction. Mixed lighting, a strong colour cast or a background full of loud colour can all pull attention away from the subject.
Choose it when the light is the interesting part. A beam through a window or a long shadow across a street is often stronger in mono.
Choose it when the mood is more important than the record. Colour tells people what a place looked like. Black and white tends to tell them how it felt.
If you are not sure, shoot normally and decide later. Keeping the original gives you both options, and a photo that disappoints in colour sometimes turns out to be your best mono frame.
Add grain with a light hand
Film photographs have grain, a fine texture made by the light-sensitive material itself. A little grain can take the edge off a sharp phone image and make black and white pictures feel more physical.
Add it after you have set exposure and contrast, and add less than you think you need. Look at the photo at the size people will actually see it, usually a phone screen. Grain that looks gentle on a small screen can look heavy when the picture is enlarged.
If the grain is the first thing you notice, reduce it. It should support the picture, not compete with it.
Common beginner mistakes
The first is converting every colour photo and hoping for the best. A picture with no clear light or no strong subject will not improve just because it is grey.
The second is pushing contrast too far, so shadows turn to solid black and highlights to white with no detail left. Check that you can still see some texture in both ends of the tonal range.
The third is ignoring composition. With less information in the frame, clean shapes and a clear subject matter even more. Move closer, remove clutter and let one thing lead the eye.
Try it in Simul
Simul Studio is a film-inspired camera and photo editor for iPhone and Android. On iPhone, the live camera shows film looks before you shoot, so you can judge the tones while you frame the picture.
For black and white, the iPhone looks include ones based on Kodak Tri-X 400 and Ilford HP5. Tri-X has a reputation for punchy contrast and visible grain, which suits street scenes and hard light. HP5 tends to feel a little softer and more flexible, which suits portraits and overcast days. Try both on the same photo and compare.
Once you have a look you like, open the darkroom to adjust exposure, contrast, curves and grain. Editing is non-destructive and your original is always kept. You get five free exports to try it, then it is a one-time purchase with no subscription and no account.