Following is a step-by-step guide on how to clean the Pentax Super A's focusing screen. The author is not a repairman, nor has he received formal instructions on camera maintenance or repair. The author's knowledge of the subject was derived from observation, his own experimentation and experience, largely driven by curiosity and the high cost of camera repair. The author has no knowledge whether the manufacturer built Super As in varying specifications, or whether these cleaning instructions are applicable to all Super As. That said, the author had performed this procedure on his own Super A, and the body remains functional to this day. The author had also seen the same procedure performed by a repairman on a Program Plus.
Dirt in the viewfinder is one of those unavoidable problems inherent with age, like falling hair and tooth decay in people. Most of the time a blower brush will work well to keep the dirt off. But when the dirt gets between the prism and the viewfinder, no amount of shaking and blowing will suffice. That's when you have to remove the focusing screen. Fortunately for Super A owners, cleaning the focusing screen can be a very simple do-it-yourself project.
When the lens is removed, you will notice two tiny screws above the rapid return mirror just inside the lens mount (see photo below).
These two screws hold up the trapdoor-like rectangular metal housing containing the focusing screen. The housing is hinged at its opposite end. Without the two tiny screws, the housing opens downward like a trapdoor.
Remove these two screws. I use a Stanley #0 Philips-head screwdriver, although a smaller one may be more appropriate. The two screws are so tiny they're difficult to retrieve or hold with the fingers. I use my wife's tweezers to hold them.
With a little nudge, the housing will open downward. The focusing screen itself has a metal frame. Hold the focusing screen by its metal frame using tweezers, and gently pull it out. Note the orientation of the focusing screen in its housing.
Clean the focusing screen with a blower brush. I prefer to use a mini-vacuum cleaner powered by four AAs. If the dirt is stubborn you can wipe the focusing screen with lens tissues lightly soaked in cleaning solution. I prefer to follow this up with a microfiber cloth and some more vacuuming.
The focusing screen is not fragile. I dropped it on a wooden floor and it didn't break. With the trapdoor-like housing down the underside of the prism is also accessible and may be cleaned in the same manner if necessary.
To re-install the focusing screen, just pop it in, lift the trapdoor-like housing back up, and replace the screws. The housing has two leaf springs that keep the focusing screen pressed against the prism, so there should be a slight downward pressure against the housing. While holding up the housing, use tweezers to hold the screws by the head and stick them in one at a time. Tighten the screws.
The viewfinder should now be clean as new.
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©1998 PhSantiago