Every photo is made from three settings working together: aperture, shutter speed and ISO. Photographers call this the exposure triangle. Change one, and you have to change another to keep the same brightness. Once you understand how they trade off, you can leave Auto mode and take control of every shot.
1. Aperture: How Wide the Lens Opens
Aperture is the opening inside the lens, measured in f-numbers like f/1.8, f/4 or f/11. The confusing part: a smaller number means a bigger opening and more light.
- Wide aperture (f/1.4 – f/2.8): lots of light and a blurred background. Great for portraits and low light.
- Middle (f/5.6 – f/8): sharp and balanced. Good for street and travel.
- Narrow (f/8 – f/16): less light, and more of the scene in focus from front to back. Ideal for landscapes.
2. Shutter Speed: How Long the Sensor Sees Light
Shutter speed is how long the shutter stays open, from fractions of a second to many seconds.
- Fast (1/500 s or faster): freezes motion. Birds in flight, sports, dancers.
- Normal (1/60 – 1/250 s): everyday handheld photos.
- Slow (1/30 s and slower): shows motion as blur and needs a tripod. This is the world of long exposure photography.
A handy rule: to avoid shake when handheld, use a shutter speed at least 1 divided by your focal length. At 200 mm, use 1/200 s or faster.
3. ISO: How Sensitive the Sensor Is
ISO brightens the image electronically. Low ISO (100–400) gives the cleanest files. High ISO (3200 and above) lets you shoot in dim light but adds grain, called noise. Modern cameras handle ISO 3200–6400 well, so don’t be afraid to raise it rather than miss a sharp shot.
How the Three Work Together
Each full step in any setting, called a “stop”, doubles or halves the light. To keep the same exposure, a change in one must be balanced by another:
| If you… | You gain | Balance it by |
|---|---|---|
| Open aperture f/8 → f/5.6 | Twice the light, softer background | Faster shutter, or lower ISO |
| Speed up shutter 1/125 → 1/250 s | Sharper motion | Wider aperture, or higher ISO |
| Raise ISO 400 → 800 | Twice the brightness | Faster shutter, or narrower aperture |
Starting Settings for Common Situations in Nepal
| Situation | Aperture | Shutter | ISO |
|---|---|---|---|
| Himalayan landscape, sunny day | f/8 – f/11 | 1/250 s | 100 |
| Portrait in open shade | f/2 – f/2.8 | 1/250 s | 100 – 400 |
| Street scene in Asan or Patan | f/5.6 | 1/250 s | Auto ISO |
| Birds in Chitwan or Koshi Tappu | f/5.6 – f/8 | 1/1000 – 1/2000 s | Auto ISO |
| Tihar lamps at night, handheld | f/1.8 – f/2.8 | 1/60 s | 1600 – 3200 |
Which Mode Should You Use?
- Aperture priority (A or Av): you choose the aperture, the camera picks the shutter. Best for most landscapes and portraits.
- Shutter priority (S or Tv): you choose the shutter, the camera picks the aperture. Best for action and wildlife.
- Manual (M), often with Auto ISO: full control. Best for night, long exposure and tricky light.
Practise and Share
Pick one setting to explore each week. Shoot the same scene at f/2.8, f/8 and f/16, or at 1/1000 s and 1/4 s, and compare. When your photos start to look the way you imagined, upload them to Image Pasal and let buyers find them.
Frequently Asked Questions
What is the exposure triangle?
The relationship between aperture, shutter speed and ISO, the three settings that control how bright a photo is.
Which setting should I change first?
Decide what matters most: background blur (aperture), motion (shutter) or clean files (ISO). Set that first, then adjust the others.
Is high ISO bad?
No. A slightly noisy sharp photo is better than a clean blurry one.
