Replacing the 159 focus screen

The 159 focus screen is not considered user replaceable despite it being fairly easy to remove. The problem is refitting it. In the user manual it says the screen should only be replaced at a service centre and with good reason. If not done correctly the screen will, almost certainly, be damaged. I know, I've done it.

I experimented with an old screen to see if I could find a way the screen could be changed without damaging it. Described here is my method found through that experimentation, it's not a manufacturer recommended way.

Before proceeding a method of holding the screen without damaging it is necessary. Later camera models had screens with a tab to be used to hold the screen by but the 159 screen doesn't have a tab. I use a pair of flat tipped tweezers that have had the tips covered in heat shrink cable insulation. This is permanent and I only use them for this purpose but a temporary solution could be some rubber sleeving fitted over the end of some tweezers.

I also recommend the mirror buffer foam be removed. This makes it easy to see the release catch.

First, the camera needs to held inverted.

A piece of card needs to be cut and bent to fit into the camera such that the edge sits against the back of the focus screen frame (see arrow in next picture). The card will stop the frame jumping out of its retaining slot and will also protect the mirror from possible scratching.

Release the screen by pulling back on the catch. The screen frame will pop up. Lift it up and remove the screen from underneath. This is best done by using something with a point to press against the edge of the screen and lift it up then use the covered tweezers to grab the screen and remove it while holding the frame clear. Don't try and remove the frame first, you will probably scratch the screen while trying to remove the frame.

If you do remove the frame after removing the screen, note it has two tabs on it, a wide one on one side and a narrow one on the other, The wide ones goes to the back, the narrow one to the front.

Refitting is the reverse order to the above. Fit the frame first, hold it clear and fit the screen under it. Note the dull (matte) side of the screen goes towards the prism.

Finally, lower the frame but DO NOT try and press down on it to engage it with the latch.

Use a pair of tweezers to pull the latch back as far as it will go. Use the tweezers against the mirror box frame and make sure the latch is held firmly before going further.

This is the most important part of the process. If the latch isn't held back the frame, which is quite flimsy, will get pushed inwards and will scratch the surface of the screen.

With the latch held back, hold the frame into position then release the latch.

This is not an easy procedure to carry out and requires practice of using two pairs of tweezers and a steady hand.

Canon EOS EF Eyecup will fit Contax and Yashica

The Kyocera F-3 eyecup was used on the Contax S2, 167, Aria and maybe other bodies. It also fits earlier bodies like the 139, 137 and 159 and also Yashica bodies like the FX-3, FX-D, FX-103 etc. I, personally, prefer it to the round eyecups that were used on the earlier Contax and Yashicas.

However, the Kyocera F-3 eyecup has become scarce and when they do become available they are expensive. So I looked for an alternative and found the Canon EOS EF eyecup fits perfectly. It's the same style as the Kyocera F-3 though slightly different in shape. Original Canon eyecups are available and are not expensive but there are Chinese made copies that are available very cheaply on ebay.

The Canon EF eyecup fits Canon EOS 350D, 400D, 450D, 500D, 550D, 600D, 1000D etc. bodies. There are other similar models so, if buying, check it's the correct one.

Here's a few pics of one I bought fitted to a FX-3, a 139 and the KF-M1 mentioned in my previous post.

And a couple of pictures of the eyecup itself.

An unusual fault

Thought I'd document a fault I saw recently as it's an unusual one.

The symptoms are that, when a manual shutter speed is selected and the camera not cocked, when the shutter release button is pressed, the LED in the viewfinder that indicates the selected shutter speed will come on immediately but the LED showing the shutter speed required will not come on until after a period equal to the selected shutter speed. And if B is selected, it will never come on.

The cause was a faulty transfer switch - the first type which is a sealed micro switch. Normally, when these fail the camera won't release the shutter as the transfer switch goes open circuit and the processor never gets the signal to say the shutter is cocked. In this case, the switch went short circuit so the processor thought the shutter was cocked even though it wasn't. Consequently, the processor would activate the shutter magnet for the selected shutter speed and, for reasons I don't understand but it's probably just part of the programming, the meter is not activated and the LED showing the suggested shutter speed isn't lit.

This is only unusual in the way the transfer switch failed. I've never seen one fail this way before. And, because the camera otherwise worked normally, there was little to indicate what the issue was.