Long Exposure Photography: Settings, Gear, and Post-Processing

Long exposure photography uses a slow shutter speed — anywhere from 1/4 second to several minutes — to blur motion while keeping static elements sharp. Moving water becomes silky smooth. Car headlights trace glowing lines through city streets. Clouds streak across the sky in painterly smears. Stars draw circles around the celestial pole.

The technique is simple in concept (keep the shutter open longer), but the execution involves gear choices, exposure math, and post-processing that matter. This guide covers the camera settings, essential gear, phone alternatives, and editing workflow.

What Long Exposure Does to Different Subjects

Camera Settings for Long Exposure

The Exposure Triangle

Long exposure shifts the exposure triangle: you need a much longer shutter speed, which means reducing ISO and aperture to compensate and avoid overexposure.

Exposure Time Calculation

When adding an ND filter (which reduces the light reaching the sensor), you need to recalculate the shutter speed:

New shutter speed = Base shutter speed × 2^(ND filter stops)

A 10-stop ND filter turns a 1/60s daytime exposure into a 16-second long exposure — enough to blur water and clouds dramatically.

Essential Gear

Tripod

Non-negotiable for any exposure longer than ~1/15 second (handheld limit). A stable tripod eliminates camera shake that would blur the entire image instead of just the moving elements.

What matters: Weight capacity (should exceed your camera + lens weight by 2×), leg lock type (twist locks are faster; flip locks are more reliable in cold), and center column (avoid extending it — it reduces stability).

ND Filters

Neutral density filters reduce light without affecting color. They let you use long shutter speeds in daylight conditions where the scene would otherwise be massively overexposed.

Recommendation: A fixed 10-stop ND (ND 3.0) covers 90% of long exposure scenarios. Brands: B+W (MRC-coated, minimal color cast), Hoya ProND, NiSi. Avoid cheap ND filters — they introduce color casts (usually magenta or green) that are time-consuming to correct in post.

Remote Shutter Release

Pressing the shutter button physically introduces vibration. Use a wired remote, wireless remote, or the camera's 2-second self-timer to trigger the shutter without touching the camera.

Method 1: DSLR / Mirrorless Camera

Step-by-Step

1. Mount camera on tripod. Level it using the built-in level or a bubble level.
2. Compose and focus. Use autofocus to lock focus on your subject, then switch to manual focus. Do not refocus after this.
3. Attach ND filter if shooting in daylight.
4. Set exposure. Manual mode: ISO 100, aperture f/11, calculate shutter speed (or use a long exposure calculator app).
5. Set Bulb mode if you need more than 30 seconds. Use a remote shutter to open and close the shutter.
6. Shoot a test frame. Check histogram — you want the data centered or slightly left (underexposed slightly is better than blown highlights for long exposure).
7. Shoot the final image. Multiple frames at the same settings give you options and allow for noise reduction stacking in post.

Method 2: iPhone (iOS 18) — Live Photo Trick

iPhones cannot natively set a multi-second shutter speed, but iOS's Live Photo feature captures a burst of frames that can be composited into a simulated long exposure.

Steps

1. Open the Camera app. Ensure Live Photo is enabled (the concentric circles icon is yellow).
2. Hold the phone steady (ideally propped against something stable) and tap the shutter.
3. Open the photo in the Photos app.
4. Swipe up on the photo and under Effects, select Long Exposure.
5. iOS blends the 3 seconds of Live Photo frames into a single image with motion blur.

Limitations: The effective "exposure" is only 3 seconds — not enough for star trails or very smooth ocean blur. Works well for waterfalls, light trails, and moderate motion. The phone must be very steady — any camera shake blurs the entire image, not just the moving elements.

Third-Party App: Slow Shutter Cam (iOS, v6.4)

Slow Shutter Cam v6.4 ($2.99) provides actual control over exposure time (up to 60 seconds) with three capture modes: Motion Blur, Light Trail, and Low Light. It composites frames in real-time to simulate a long exposure without an ND filter.

Method 3: Android (Google Camera v9.3 + Third-Party)

Google Camera does not have a native long exposure mode, but the Night Sight feature uses multi-frame compositing to achieve similar results in low light.

Third-Party: Camera FV-5 (v5.3.5, $3.95)

Camera FV-5 provides full manual control including shutter speeds up to 60 seconds (hardware-dependent). On phones with Pro/Manual camera mode (Samsung, OnePlus, Pixel with Camera2 API support), you can also access long shutter speeds natively.

Post-Processing Long Exposures

Noise Reduction

Long exposures generate thermal noise — colored pixels (hot pixels) that appear in dark areas. Two approaches:

1. In-camera Long Exposure Noise Reduction (LENR). The camera takes a "dark frame" (same duration, shutter closed) and subtracts its noise pattern from the actual image. Doubles the capture time. Worth enabling for exposures > 30 seconds.

2. Software noise reduction. In Lightroom Classic v13.x or Adobe Camera Raw: use the Detail panel, Luminance noise reduction slider. Start at 25-40 for long exposures. For stacked images, averaging multiple frames naturally reduces random noise.

Color Cast Correction

ND filters, especially lower-quality ones, introduce a color cast. In Lightroom or Photoshop:

1. Use the White Balance eyedropper on a neutral area (gray card, white wall).
2. Fine-tune with the Temperature and Tint sliders.
3. B+W MRC and NiSi filters have minimal cast; cheap filters may need significant correction.

Contrast and Clarity

Long exposure images often look flat out of camera because the motion blur averages tonal values. Boost:

• Contrast: +10 to +20 in Lightroom
• Clarity: +15 to +30 (enhances mid-tone contrast, making the sharp elements crisper)
• Dehaze: +5 to +15 if shooting near water (moisture in the air reduces contrast)

After editing, compress your final image for web sharing — long exposure photos at high resolution can easily exceed 10 MB.

Star Trail Photography

Star trails are the most extreme form of long exposure — 15 minutes to several hours of exposure capturing Earth's rotation.

Stacking Method (Recommended)

Instead of a single multi-hour exposure (which introduces massive thermal noise):

1. Set camera to interval shooting: 30-second exposures, 1-second gap, for 60-240 frames.
2. Use ISO 800-1600 (stars need more light than daytime long exposures).
3. Process in StarStax v0.71 (free, Windows/macOS/Linux) or Photoshop. Stack all frames using Lighten blend mode — each frame's star positions combine into continuous trails.

The stacking method produces much cleaner results than a single long exposure and allows you to remove any single frame that has an airplane or satellite trail.

FAQ

What shutter speed makes water look smooth? 1-5 seconds for flowing streams and waterfalls. 10-30 seconds for ocean waves to become fog-like mist. The exact speed depends on how fast the water moves — faster water needs less time to blur.

Do I need an ND filter for long exposure? In daylight, yes. Without an ND filter, even at f/16 and ISO 100, a bright scene will be massively overexposed at shutter speeds over 1/30s. At night or dusk, you can shoot long exposures without an ND filter.

Why is my long exposure photo completely white? Overexposure. The shutter was open too long for the amount of light. Use a stronger ND filter, smaller aperture, or shorter exposure time. Check the histogram — it should not be clipped at the right edge.

Can I do long exposure handheld? For shutter speeds up to about 1/4 second, modern IBIS (in-body image stabilization) can produce usable results handheld. For anything longer, a tripod is essential. Handheld long exposures produce overall image blur, not selective motion blur.

What is the difference between long exposure and HDR? Long exposure uses a single, slow shutter speed to blur motion. HDR merges multiple exposures at different brightness levels to capture more dynamic range. They can be combined — an HDR panorama of a long exposure scene captures both motion blur and wide dynamic range.

How do I avoid hot pixels in long exposures? Enable in-camera Long Exposure Noise Reduction (LENR) for exposures over 30 seconds. Alternatively, shoot a dark frame (lens cap on, same settings) and subtract it in post using Photoshop (Image → Apply Image → Subtract blend mode).