Lens Cap Guide: Snap-On vs Rear Caps
By The Camera Exchange | Published: 2026-10-29
Category: Buying Guides
Learn the differences between snap-on and rear lens caps, and find the right protection for your camera gear.
Quick answer
Choose a snap-on lens cap for front element protection while shooting, and a rear lens cap to keep dust off the mount when the lens is stored.
Snap-on vs Rear: Different Jobs
A snap-on lens cap clips onto the front of the lens to shield the glass from scratches, dust, and accidental bumps. It is the cap you pop off before every shot and replace when you stow the camera.
A rear lens cap covers the metal mount at the back of the lens. Its main job is to keep dust and debris off the electrical contacts and the rear element while the lens is off the camera body.
Fit Matters More Than You Think
Front lens caps are sized by filter thread diameter (e.g., 39mm, 77mm). Using the wrong diameter means the cap either won't stay on or will scratch the barrel. Rear caps are specific to the lens mount system — a Nikon F rear cap will not fit a Sony A-mount lens, and vice versa.
The ProMaster Rear Lens Cap for Nikon F is a budget-friendly option that does the job reliably, while the Sony ALCR55 Rear Lens Cap is designed specifically for Sony A-mount lenses.
Material and Build Trade-offs
Snap-on caps are typically made from rigid plastic with a spring-loaded center clip. Cheaper caps may feel flimsy and crack over time, while more expensive ones like the Nikon LC-77 offer a sturdier build and a smoother snap action.
If you frequently swap lenses in dusty environments, investing in a well-sealing rear cap can save you sensor cleaning headaches later.
How to choose your lens cap
- Identify the cap type you need: Front snap-on cap for everyday lens protection; rear cap for storage and transport. Most lenses come with a front cap, but rear caps are often sold separately. Check whether your lens already includes a cap before buying.
- Match the size or mount: For front caps, look for the filter thread diameter printed on the lens barrel or in the manual (e.g., 39mm, 77mm). For rear caps, match the lens mount system (e.g., Nikon F, Sony A).
- Consider build quality: A cap that feels loose or too tight can be a nuisance. Try a branded option like the Nikon LC-77 for a precise fit, or a value option like ProMaster if you need multiple caps.
Product facts
- ProMaster Rear Lens Cap – Nikon F: Price Guarantee Rent Now The ProMaster Rear Lens Cap for Nikon F is an affordable, reliable choice for protecting your Nikon lenses when they are off the camera.
ProMaster Rear Lens Cap – Nikon F - Nikon LC-77 77mm Snap-On Lens Cap: Price Guarantee Rent Now The Nikon LC-77 77mm Snap-On Lens Cap offers a premium fit and durable construction for photographers who want a cap that stays put.
Nikon LC-77 77mm Snap-On Lens Cap
Who should buy which cap
Best for
- Photographers who want a reliable, affordable rear cap for Nikon F lenses — ProMaster Rear Lens Cap
- Shooters with a 77mm filter thread who prefer a snug, durable snap-on cap — Nikon LC-77
Not for
- Users with Sony A-mount lenses looking for a rear cap — choose the Sony ALCR55 instead
- Anyone needing a front cap for a non-77mm thread — check the diameter before buying
