Beginner’s Guide to DSLR Photography: Lens Choice, Exposure Basics, and Composition

If you’re moving beyond auto mode, your DSLR can become a deliberate, creative tool. This guide builds a solid foundation in lens choice and exposure (aperture, shutter, ISO), then layers on composition so your photos are not just technically correct but compelling. You’ll get actionable setups you can try today, plus best practices that help you shoot with confidence.

How DSLRs See: Sensors, Field of View, and Lenses

A DSLR’s sensor size and your lens’s focal length together define what your photo looks like. Most DSLRs are either APS-C (crop) or full-frame. APS-C sensors are smaller, so they crop the image circle—making lenses feel “longer.”

• Crop factor: Canon APS-C ≈ 1.6×; Nikon/Sony/Fuji APS-C ≈ 1.5×. Multiply focal length by this factor for the full-frame equivalent field of view. A 50 mm on APS-C behaves like ~75–80 mm on full-frame.

Choosing focal length

• Wide (10–24 mm APS-C, 16–35 mm FF): Expansive scenes, architecture, environmental portraits. Exaggerates perspective; watch for distortion near edges.
• Normal (30–35 mm APS-C, 50 mm FF): Natural perspective; versatile for street, travel, and documentary.
• Short telephoto (50–85 mm APS-C, 85–135 mm FF): Flattering portraits; compresses background and isolates subjects.
• Telephoto (70–200 mm+ FF equivalent): Sports, wildlife, distant details. Requires faster shutter speeds to avoid blur.

Tip: If you own a kit zoom (e.g., 18–55 mm APS-C), learn its endpoints. Practice at 18, 35, and 55 mm so you feel how perspective changes.

Prime vs. zoom

• Primes (single focal length, e.g., 35 mm, 50 mm): Typically sharper, lighter, and faster (wider maximum aperture like f/1.8). Great for low light and subject isolation.
• Zooms (e.g., 24–70 mm, 70–200 mm): Flexible framing without moving. Modern zooms are optically excellent but often slower (f/2.8–f/4 on mid/high-end; f/3.5–5.6 on kit lenses).

Recommendation: A 50 mm f/1.8 (FF) or 35 mm f/1.8 (APS-C) is an affordable prime that instantly expands low-light and portrait possibilities.

Aperture matters on the lens

A lens’s maximum aperture (smaller f-number is wider) dictates how much light you can gather and how shallow your depth of field (DoF) can be. For portraits, f/1.8–f/2.8 isolates subjects. For landscapes, f/8–f/11 maximizes sharpness front-to-back. Beware of diffraction at very small apertures (f/16–f/22) on APS-C, which can soften detail.

Stabilization and filters

• Image stabilization (IS/VR/OS/IBIS) helps with slow shutter speeds but doesn’t freeze moving subjects.
• Turn stabilization off on a tripod to prevent micro-vibrations (unless your camera explicitly supports tripod mode).
• Carry a circular polarizer for skies and reflections and an ND filter when you need slow shutter speeds in bright light.

Exposure Basics: Aperture, Shutter, ISO

Exposure is a balance between three controls. Each “stop” doubles or halves light.

Aperture (f-number)

• Controls depth of field and light. Lower f-number = wider aperture = more light + shallower DoF.
• Creative use:
  • Portraits: f/1.8–f/2.8 for background blur and eye focus.
  • Landscapes: f/8–f/11 for sharpness front-to-back (hyperfocal focusing helps).
  • Groups: f/4–f/5.6 to keep multiple faces sharp.

Shutter speed (time)

• Controls motion. Faster shutters freeze action; slower shutters blur motion creatively.
• Baselines:
  • Handheld minimum: reciprocal rule—use at least 1/(effective focal length). On APS-C at 50 mm, aim for 1/80–1/100 s. Stabilization can buy 2–4 stops for static subjects.
  • People in candid scenes: ~1/125–1/250 s.
  • Sports/wildlife: 1/500–1/2000 s depending on speed.
  • Creative blur (waterfalls, light trails): 1/4 s to multi-seconds with tripod.

ISO (sensor sensitivity)

• Raises signal and noise. Increase ISO to maintain shutter speed in low light.
• Practical ranges:
  • Base ISO (100–200): Maximum quality.
  • Moderate (400–1600): Good trade-off for indoor/night with motion.
  • High (3200–6400+): Usable on many modern DSLRs; expect more noise—expose carefully.

Balancing exposure: simple workflow

• Decide creative priority first:
  • Need blur or DoF control? Use Aperture Priority (A/Av).
  • Need to freeze action? Use Shutter Priority (S/Tv).
  • Need full control or consistent studio work? Manual (M) with Auto ISO can be efficient.
• Exposure compensation (+/–) in semi-auto modes nudges brightness without changing your chosen priority.
• Watch your histogram: aim to preserve highlights (don’t slam up against the right edge). Slightly underexpose high-contrast scenes to protect bright areas; lift shadows in post if you shoot RAW.

Metering modes and when to use them

• Evaluative/Matrix: Default for general scenes; considers the entire frame.
• Center-weighted: Good for subjects near the center when background brightness varies.
• Spot: Precisely meter a small area (e.g., a face). Recompose after metering or use AE-Lock.

Common pitfall: Spot metering off a dark jacket will overexpose the whole scene. Know what you’re metering and why.

Autofocus and Sharpness Control

• AF modes:
  • Single (AF-S/One Shot): Locks focus—best for still subjects.
  • Continuous (AF-C/AI Servo): Tracks moving subjects—sports, kids, pets.
• AF areas:
  • Single point: Precision on the eyes.
  • Dynamic/Zone: A small cluster for erratic subjects.
  • Wide/Auto: Let the camera decide; works in simple scenes but can grab the wrong subject.

Best practices:

• Prioritize eye focus in portraits; use single-point AF on the nearest eye.
• Consider back-button focus to separate focusing from shutter release—reduces focus errors.
• Use burst mode (low/medium) with AF-C for action; refine timing.

Sharpness checklist:

• Shutter speed: Follow or exceed the reciprocal rule.
• Support: Brace elbows, use a wall or monopod, or go tripod for critical sharpness.
• Diffraction: Avoid stopping down beyond f/11 on APS-C unless you need the DoF.
• Micro-adjustments: If your DSLR supports AF fine-tune and a lens consistently front/back focuses, calibrate.

Practical Setups You Can Try Today

Use these as starting points; adjust for light and subject distance.

Portrait in window light (no flash)

• Lens: 50–85 mm (FF) or 35–50 mm (APS-C) prime.
• Settings: Aperture Priority; f/2–f/2.8; ISO 200–800; watch shutter ≥ 1/125 s.
• AF: Single-point on nearest eye.
• Metering: Evaluative; dial +0.3 to +0.7 EV if the background is bright.
• Composition: Angle subject ~45° to window; use the window as a large soft light; place eyes along top third.

Travel/street walk

• Lens: 35 mm (FF) or 24 mm (APS-C) prime, or a 24–70 mm.
• Settings: Auto ISO capped at 3200; Aperture Priority; f/4–f/5.6; minimum shutter 1/250 s.
• AF: AF-C with small zone for responsiveness.
• Tip: Anticipate moments—pre-focus at a typical distance to reduce lag.

Landscapes at golden hour

• Lens: Wide zoom (16–35 mm FF/10–20 mm APS-C).
• Settings: Manual; f/8–f/11; base ISO; choose shutter as needed (often 1/4–1/30 s). Use tripod.
• Focus: At or just beyond the hyperfocal distance; live view magnification helps.
• Extras: Use a 2-second self-timer or remote; enable mirror lock-up if available.

Indoor action (kids/pets)

• Lens: 50 mm f/1.8 or 70–200 mm f/2.8 (space permitting).
• Settings: Shutter Priority 1/500 s; Auto ISO up to 6400; widest available aperture.
• AF: AF-C, small zone; use burst.
• Tip: Expose for faces; don’t be afraid of higher ISO—sharp with some noise beats blurry and clean.

Composition Essentials That Elevate Your Shots

Technical exposure gets you a clean file; composition tells the story.

Rule of thirds and visual balance

• Place key subjects along the grid lines or at intersections to create tension and flow.
• Balance a large subject with a smaller counterweight opposite it.
• Break the rule intentionally when symmetry or central framing strengthens the image.

Leading lines, framing, and layers

• Use roads, fences, or streams to lead the eye to your subject.
• Frame with doorways, branches, or archways to add context and depth.
• Add foreground interest (rocks, flowers, silhouettes) to create layers and a sense of scale.

Background control

• Scan edges of the frame for distractions (bright blobs, poles “growing” from heads).
• Adjust your position or focal length to simplify. Move two steps left/right more often than you zoom.
• Use depth of field intentionally: open up (lower f-number) to blur clutter; stop down to include context.

Perspective and viewpoint

• Change height: crouch for kids and pets; climb for graphic patterns.
• Wide lenses exaggerate depth; get close to emphasize scale.
• Telephotos compress distance; use them to stack mountains or simplify busy scenes.

Light, color, and contrast

• Side light reveals texture; backlight creates glow and rim light; overcast equals soft, even portraits.
• Complementary colors (blue/orange, red/green) add pop; watch for color casts with mixed lighting.
• In high-contrast scenes, expose for highlights and compose with shapes and silhouettes.

Visual hierarchy and subject clarity

• Decide what the photo is about, then remove everything that doesn’t support it.
• Use brightness contrast, color contrast, sharpness, and size to rank elements.
• Avoid tangents: keep important edges from kissing the frame border; give subjects breathing room.

Working Smart: File Quality, White Balance, and Review

• Shoot RAW (or RAW+JPEG) to recover highlights/shadows and adjust white balance without quality loss.
• White balance:
  • Auto WB is good, but set custom WB under consistent light (e.g., tungsten) for accurate skin tones.
  • Warm scenes often feel more inviting; you can bias WB slightly warmer for portraits.
• Use the histogram and highlight warnings (blinkies). Don't judge exposure purely from the rear LCD brightness.
• Bracketing: For static high-contrast scenes, shoot ±2 EV brackets for later blending.

Common Pitfalls and How to Avoid Them

• Motion blur from too-slow shutter: Raise ISO or open aperture; prioritize shutter speed for action.
• Out-of-focus eyes in portraits: Use single-point AF, faster shutter (≥ 1/125), and avoid recomposing at very shallow DoF—move the AF point instead.
• Overreliance on wide open apertures: Stop down to f/2.8–f/4 for sharper lenses and sufficient DoF when needed.
• Diffraction softness: Avoid extreme f-numbers (f/16–f/22) unless you absolutely need DoF, especially on APS-C.
• Messy backgrounds: Compose first; step to clean up; use longer focal lengths to simplify.
• Stabilization on tripod: Turn it off to prevent feedback-induced blur (unless your system detects tripod use).
• Dirty lenses/sensors: Keep a blower in your bag; clean gently and regularly.

A Quick Field Checklist

• Intent: What’s the photo about?
• Light: Direction, quality, color—how can you use it?
• Lens: Focal length that supports your story (perspective first, then framing).
• Exposure: Priority mode set? Shutter fast enough? Aperture fits DoF? ISO reasonable?
• Focus: AF mode and area appropriate; focus on the right spot.
• Composition: Edges clean; background controlled; strong subject placement.
• Review: Histogram ok; highlights retained; shoot a safety frame with slight compensation.

Next Steps

• Practice deliberately: pick one variable (e.g., shutter speed) and create a mini-project.
• Study contact sheets: keep near-misses and annotate what you’d change.
• Limit gear on walks: one lens forces you to see better.
• Seek feedback: share sets of 5–10 images with a clear intent and ask specific questions.

With a thoughtful lens choice, intentional exposure, and purposeful composition, your DSLR becomes more than a camera—it becomes a way to translate how you see into images that resonate. Grab your camera, pick one scenario from this guide, and head out to shoot today.