Why and how to replace? (When it is not officially supported)
For about a half year I am using the Canon 5D Mark III, which is a very good camera in many ways. But there is a serious flaw: The standard matte cannot be exchanged for another. You may ask: Why is this a problem?
Standard matte vs. the high-precision matte
Just for clarification: A matte is a specially crafted piece of plastic (glass?) on which the image is projected (when the DSLR is not taking a picturee). Therefore, in the viewfinder we do not see the scene, but its projected image.
The standard matte is optimized for an usage with lenses with the speed up to F5.6 and perhaps even slower. Even with such lenses it produces relatively bright image. The disadvantage is that with speed lenses (F2.8 and better) we cannot see the real depth of field. Even with 50/1.4, what we see is the DOF corresponding to apprioximately F2.5.
On the other side the high-precision matte reveals the real depth of field, which allows much better manual focusing and also shows any autofocus errors very clearly. The problem is that with slow lenses (F5.6 and slower), the image gets dark and the usage is difficult.
For illustration, here are the photos of a viewfinder of Canon 5D Mark III with Sigma 50/1.4 lens with the standard matte and with the high-precision one on the mouse over. In both cases, I tried to focus on the tip of the pliers:
In the case the mouse over isn’t working for you, here is the photo of the viewfinder with the precision matte:
You can clearly see that the image with the high-precision matte is quickly getting blurred further of the focus point.
Problem with the Canon 5D Mark III
Unfortunately, Canon decided to NOT support matte replacement with the 5D Mark III. While the 5D Mark II and plenty of lower-class APS-C Canon cameras have several matte options, the higher version has no such alternative. Various matte optims are available again for 1D X, but that model is significanly more expensive.
The standard matte pose a serious problem especially when using lenses without an autofocus, which have to be focused manually. When searching the web, wyou can find plenty of contributions in various forums from people, who hesitate to buy this camera just because of this single (non-)feature.
Luckily, there are several companies producing alterantive mattes for various cameras. The mattes are usually made by a precision cutting a larger existing matte from spare parts of a different camera to fit the particular model. For 5D Mark III there was no such alternative for a long time, but currently there is one on FocusingScreen.com. The long waiting was over and I rushed to order it.
The communication with the company and also the delivery were very good. Two days after the dispatch, I have got mail that they are very sorry, but probably forgot to put rubber fngers into the package, so they are sending it in another package. I did’t wait for that one and after the arrival of the first package I just used a one-time rubber medacal gloves. They work as well and I really recommend using one of these options as any dirt is difficult to remove from the matte.
I was really surprised to find that the package contains not only the matte and the tweezers, but also so called shims (or washers), which are this rectangular plates that can be inserted under the matte. This is to precisely position to matte in the right distance from the mirror. The distance has to be identical to the one from the mirror to the sensor. Fractions of milimetre matters and because that is outside the factory tolerances, these shims have to be used. This practice is usual, I even found two of these shims from Canon when I opened the camera.
To have another set of shims is an advantage. They are of a different width and can be used if any problem occurs. I have already exchanged a few mattes for different cameras and those times I bought mattes from Katz Eye. But there are not delivering the shims, so once time I needed them, I was out of luck and the matte was shifted by a little bit.
Here is the package contents, the shims are found on the right:
Keeping in mind the instructions from the web of the manufacturer I was done in less then five minutes.
I had a bit of experience though, because I already used an identical procedure to exchange the matte of Canon 7D, whcih is otherwise also officially fixed.
The time might be longer if there was a necessity of installing the shims, but forutnately there was no need for the this time. In the other case you would need to test the focusing, unscrew, get the matte out, change the number of shims, screw back and test again.
I am very happy with the result. You can see the change in the viewfinder on the beginning of the article. Now it is really easy to focus manually and don’t rely on the autofocus.
Just for the sake of curiosity, I compared matte of 5D Mark III and 5D Mark II, because previously I thought of exchanging the matte between these two models and hoping it would fit. But it probably wouldn’t – the mattes have different protrusions on the edges.
So for the end, just to show the mattes, from left: Canon 40D (probably), 5D Mark II and 5D Mark III. Aside the differences on the edges, you can see also the ration of APS-C to Fullframe matte, which corresponds to the sizes of their sensors:
I hope that I helped you with the decisions on at least show, that a matte is an important piece of camera.