What is a focusing screen, and where is it in an SLR/DSLR?
Asked 5/29/2012
6 views
2 answers
0
I’ve seen references to a “focusing screen” in discussions about SLRs/DSLRs. What does it do, where is it located inside the camera, and how is it used for composing or focusing?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
14y ago
2 Answers
15
On a reflex camera (those with a mirror allowing you to compose and focus through the same lens that you will shoot the picture - aka SLR or DSLR) the focussing screen is a glass surface on which the image is projected by the mirror. You can see it by removing the lens and looking inside the body above the mirror: 
When looking into the viewfinder you see the focussing glass through the prism which inverts the image (the image on the focussing screen is flipped horizontally).
The focussing screen may be engraved with design such as the focus points on a DSLR, however on high end cameras it is possible to replace the focussing screen with one displaying a grid allowing you to better compose the image or an other such design.
For manual focus purpose some focussing screens have a micro-prism in the centre which splits the image when out of focus.
Originally by user9409. Source · Licensed CC BY-SA 4.0
user9409
14y ago
0
Generated from our catalog & community — verify before relying on it.
A focusing screen is a translucent screen inside an SLR or DSLR that the lens image is projected onto by the mirror. It’s part of the optical viewfinder system: when you look through the viewfinder, you’re seeing the image formed on this screen through the pentaprism/pentamirror.
Location: remove the lens and look into the camera body. The mirror is at the bottom/front, and the focusing screen sits above it.
Purpose: it lets you compose and check focus through the taking lens. Some screens include markings such as AF points or composition grids. On some higher-end cameras, the screen can be replaced with a different type.
For manual focus, certain focusing screens use aids such as microprisms or split-image rangefinder patterns. These make it easier to judge when the subject is in focus.
This applies to reflex cameras with mirrors; mirrorless cameras do not use a traditional focusing screen in the same way.
Recommended products
UniqueBot
AI14y ago
Your Answer
Related Questions
What’s the difference between a rangefinder and an SLR, and what are the advantages of each?
How are DSLR viewfinder focus-point indicators displayed?
What’s the difference between vertical and horizontal focal-plane shutters?
What is a focusing rail, and when is it useful?
Where is the phase-detect autofocus sensor located in a DSLR?