(D)SLR Focusing Screen Experiments

Stephen Coates' Website - stevecoates.net

Created: July 2015
Updated: August 2015

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(D)SLR Focusing Screens


Many modern low end DLSRs, as well as many modern auto-focus film SLRs, have terrible focusing screens. They have no focusing aids, so manual focusing can be difficult. This makes manual focus lenses hard to use, and makes checking the camera's autofocus difficult. Excellent as autofocus is, it isn't perfect.

Many old manual focus cameras (and some modern high end SLRs) have much better focusing screens and viewfinders. On this page, I experiment to see if I can get a better focusing screen for my Canon EOS 500D.

Option 1: Buying a cheap Chinese screen

Third party screens for models like the 500D can sometimes be purchased. A more expensive option is focusingscreen.com, who offer screens manufactured from Canon and Nikon originals, similar to what I've done below, but obviously with a much better process. Sometimes cheap ones can be purchased on ebay. I bought the following screen from 'Terence Camera' in China for approx. £15.

The focusing screen arrived quickly from China. It is manufactured by a company called Bresson.

Here is is, compared to the EOS 500D's original screen:


The Bresson screen is, umm, 'average'.

The diagonal split prism and the microprism ring work quite well, however, the matte surface is not very good. In the matte area, the out of focus areas look 'milky'. They lose some contrast, but are still clearly visible. They don't look particularly blurred. This isn't as good as the original screen, and certainly not as good as the Ec-L screen (below).

I'm inclined to say that the Bresson screen is neither better nor worse than the original 500D screen. Whether or not it is worth getting will probably depend on how much you rely on the split/microprism. I think a good quality matte surface will probably be more useful for me.

View through the viewfinder with the Bresson screen. The lens is not focused properly.

A focused image on the Bresson screen.

Option 2 (failed): Cutting down a Canon Ec-L Screen

Full frame DSLRs such as the 5D and 1D have many different focusing screens available as accessories. Perhaps we can modify one to fit a crop sensor camera like the 500D? The Canon Ec-L screen should probably suite me. It has a cross split prism, and the matte surface is nice too.

This idea was inspired by Mike (of Mike's Electric Stuff). He managed to cut down a (different) full frame screen to fit his cropped frame DSLR. Read Mike's page here: http://www.electricstuff.co.uk/extube.html

Result: Unfortunately this didn't work. Although I managed to fit the screen (as shown below), the calibration is out. Therefore, when the image is in focus on the screen, it is not in focus on the sensor. I'm going to guess that this is because the Ec-L screen is too thick. It is about 2mm thick, whereas the original EOS 500D screen is thinner.

However, the screen did look very nice in the camera. The cross split prism works nicely and the image looks nice on the matte screen. It is clearly a higher quality screen than the 500D's stock screen. Too bad it seems too thick. Maybe the one Mike used in the link above in thinner? Read on to find out how I fitted the screen.

Using Mike's template, I scored the Canon Ec-L...

Snapped the sides off...

Sanded the edges...

Here, it is very easy to scratch the screen or make it dirty. Be careful. Now the screen can be popped into the camera and the retaining clip fitted.

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