About two years ago I set up one of my Pentax MZ-S cameras with a split image/microprism focusing screen. In this thread I want to share the how-to part so if someone feels they need a similar setup with their MZ-S they can do it.

What you'll need:

- a bit of courage if you have not done camera DIY before (if you feel anxious a shot of spirit /strictly one!!!!/ gets rid of shaking hand while doing fiddly jobs)

- a split image/microprism focusing screen of a Pentax MX (LX screen should be good as well).

- a very fine grain so called glass sand paper (at least P1000 but should be no more than P2000 as that is way too fine and takes longer to take off the excess on the edges of the screen). Do not use the spongy nail polishing thingy! Not suitable as that is soft and you need hard surface to keep the screen's edges straight.

- very-very fine nail file - (it is important that you do not use rough ones. The smoother the better as you should not carve off big bits of your focusing screen). If you do not have glass sand paper you can use the nail file for the whole process as long as it is has really fine grain.

- a tab with some water in it.

- examination gloves to handle the screen and avoid having your fingerprints all around it.

- tweezer (either the original tool for changing focusing screens as pictured or a small one that you can grab the pin of screen with).

- baby wipe and microfibre cloth to wipe and dry the edge of screen.

- a quiet half an hour and a clean desk.


And here is the process step by step:

1. For a start it is enough to put on one glove (on the hand you will hold the screen with).

2. Remove the original AF focusing screen from your MZ-S camera. Leave the screen holder open.

3. Prepare the sandpaper: put some water on it. You should only wet the paper but should not have excess water or water drops on the surface. The thumb rule is that if you lift the paper and hold it vertically there should be no water dropping from it.
The water is there to absorb fine dust so you won't need to clean the screen later (you'll only need to wipe the edges at the end).
During the process (described later) wet the paper from time to time as needed.

4. With one hand (thumb and pointing finger) hold the paper down on the desk by stretching it.

5. As pictured start filing the three edges of your focusing screen (left, right and back edge). Make sure that you count the moves on each side. That enables you to take off even amount on each edge. The back does not need much adjustment. It is the left and right edge that needs more taken off. From time to time try to fit the screen into the holder. You do not need to put it in properly, just have it measured by eye. (You cannot put it in anyway as you have not adjusted the pin on the front yet. If you wish you can start with adjusting that one first and doing the edges second.)

6. File some excess off of the pin. About 1/3 on the inner side of the pin closer to the centre should be filed off.

7. When it seems that it fits the MZ-S' screen holder insert it and close the holder until it locks in place. Please note that the holder of MZ-S has flat springs/pressure plates that push up and hold the screen off the holder frame itself so you need to be careful. If you feel it still does not fit perfectly do not force it just file some excess off on the edges and on the pin. Even if it goes in a bit loose it will not fiddle around as the flat pressure spring/plates will hold the screen firm.
Obviously before placing the screen wipe the edges with baby wipe and dry it with the microfibre cloth. Make sure you only wipe the edges and avoid touching the screen. That saves you cleaning the whole screen.

Well, that is it. If you feel that this description is a bit messy just ask before attempting anything with your camera. Please only do the above process if you feel confident as I only provided this as a guideline out of experience but I will not take any blame if you mess something up with your MZ-S. You do it at your own risk (although there is not much risk if you do not force the screen).

The pictures presented here are purely for demonstration as I did this project about 2 years ago. Back then I used glass sand paper with water for the edges as described above. If you use file as pictured it is adviseable to use water as dust absorbent as I did with the paper.