First and foremost, anyone who has not cleaned one of these before, don't. It's a specialist job.
The screen must be removed to clean it. This is best done in an ultrasonic bath, exactly what cleaning agents to use depends on what the smudge is, but do not use solvents. The screen may be made from pastic, and solvents will ruin it. When clean the screen must be rinsed with distilled water and air dried.
To remove it the camera must be opened-up and the prism removed. To see how this may be done look at this Pentax camera repair website.
What kind of camera? Some camera's have removable fresnel lens held on by a spring loaded frame. Other camera's must be disassembled to replace the lens. There is no way to repair a damaged fresnel lens. Pentax K1000 must be disassembled.
Answers & Comments
First and foremost, anyone who has not cleaned one of these before, don't. It's a specialist job.
The screen must be removed to clean it. This is best done in an ultrasonic bath, exactly what cleaning agents to use depends on what the smudge is, but do not use solvents. The screen may be made from pastic, and solvents will ruin it. When clean the screen must be rinsed with distilled water and air dried.
To remove it the camera must be opened-up and the prism removed. To see how this may be done look at this Pentax camera repair website.
What kind of camera? Some camera's have removable fresnel lens held on by a spring loaded frame. Other camera's must be disassembled to replace the lens. There is no way to repair a damaged fresnel lens.
Pentax K1000 must be disassembled.