Points in Focus Photography

Canon Ec-S Focusing Screen Review

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The Canon Ec-S Super Precision Matte focus screen is a user interchangeable focus screen that allows EOS-1 series users to see the shallow depth of field associated with fast lenses in the viewfinder.

User replaceable focus screens provide an easy way to change the functionality of the viewfinder and are a feature of many of Canon’s digital SLRs. Canon produces 3 basic types of focus screen for all of their cameras that support interchangeable focus screens.

  • Standard precision matte screens are designed to balance viewfinder brightness and good out-of-focus blurring when used with lenses that have a maximum aperture of f/4 or f/5.6.
  • Super precision matte screens are designed to more accurately show depth of field especially when used with lenses with a maximum aperture of f/1.8 to f/2.8.
  • Standard precision grid screens are standard precision screens with etched grid lines for composing the image.

Ec-S Features and Requirements

The Ec-S focusing screen is physically compatible with Canon’s EOS-1 series professional SLRs, including the EOS-1D, EOS-1Ds, EOS-1V and EOS-1N series of cameras. However, built in compensation for metering isn’t supported prior to the EOS-1D mark 3 and EOS-1Ds mark 3.

The Ec-S screen is optimized for lenses with maximum apertures between f/1.8 and f/2.8. Outside of that range Canon states the following will happen:

  • With lenses faster than f/1.8, the auto focus reticle and spot metering circle may become difficult to see.
  • With lenses slower than f/2.8, the screen will appear darker than the standard focusing screen.

Evaluating the Ec-S Screen

The focus screen and installation tool in its case.

In the Package

The Ec-S screen comes in a small box that contains an instruction sheet and a hard plastic case with the Ec-S screen and the tool to change screens.

Installation

  1. Place the camera on a flat surface with the lens mount facing up.
  2. Use the provided tool to release the catch on the focus screen holder at the top of the mirror box.
  3. Remove the old focus screen by grasping the small tab with the provided tool and place it on a clean soft surface, like a Pec-Pad, or in its case.
  4. Insert the new screen by holding the small tab and placing it in the holder.
  5. Use the provided tool to close the focus screen holder until the latch clicks.

Because the Ec-S screen, like most focus screens, changes the brightness of the viewfinder, the camera must also be configured to meter correctly.

  • For the 1D Mk. 4, set Custom Function IV-12 to option 2.
  • For the 1D and 1Ds Mk. 3, set Custom Function IV-11 to option 2.
  • For the 1D Mk. 2N, set Custom Function 00 to option 2.

There is no setting for the Ec-S screen in EOS-1D Mark 2 or 1Ds Mark 2, therefore they are unable to meter properly with this screen installed.

Focus and Depth of Field

The Ec-s does a very good job at showing the depth of field more accurately. Even with an f/1.8 lens, it’s easy to tell what is in focus. Additionally the viewfinder feels slightly sharper due to the higher resolution screen.

Viewfinder Brightness

Compared to the Ec-C IV, the viewfinder was noticeably darker. My first reaction looking though the viewfinder was, “this isn’t good at all”.

Aperture Difference in stops
f/1.8 0.44
f/2.0 0.87
f/2.8 1.27
f/4.0 1.63
f/5.6 2.20
f/8.0 2.17
f/11 2.73
f/16 >3

I tired the screen in an environment that better reflected the real world, an average residential interior lit between Ev 5 and EV 8 (7.4 to 60 foot candles) with f/1.8 an f/2.8 lenses. I found the difficulty of using the viewfinder varied between moderate and hard, depending on brightness, subject contrast and maximum aperture.

At EV 5, it was very difficult for me to determine where I was focusing, especially with an f/2.8 lens. I found myself relying on the AF confirmation light, the exact thing I was trying to avoid with the Ec-S. On top of that, the overall experience was frustrating since everything was so dark. Even at EV 8, things were more manageable, at least if the subject had relatively high contrast.

When there isn’t a lot of light to start with, I found the darker viewfinder quickly negated the increase in precision.

Slower Lenses

Changing focus screens is not something I’d want to do in the field. Moreover, it’s not unlikely that a situation might arise where an Ec-S equipped camera would need to be used with a slower lens. In fact, this would be a frequent condition for me, since my long lenses aren’t f/2.8 or faster.

Unfortunately, the results were disappointing. While the viewfinder was slightly sharper, at f/4 it was also 1-2/3 stops dimmer. Indoors, the dark viewfinder made things unworkable quickly. Even if there was enough light to shoot, there often wasn’t enough to compose or focus. At f/8, the slowest aperture that can auto focus on a 1-series body, the viewfinder was very dim even in full daylight.

Conclusions

The Ec-S high precision matte screen is a specialist tool, though I have a hard time figuring out where it fits any more. The Ec-S does do a very good job at what it was designed to do, as long as you’re prepared for a dark viewfinder. In a studio with bright modeling lights or outside in broad daylight with f/2 and faster lenses, the Ec-S is certainly usable. However, if you use f/4 or slower lenses or teleconverter combination, the Ec-S is not a good choice.

Personally, I find it’s simply too dark to be useful for me, even when paired with f/2.8 or faster lenses.

Unfortunately, Canon doesn’t have a good solution for photographers using f/2.8 to f/5.6 lenses that shows focus well at f/2.8 and doesn’t make the viewfinder very dim at f/5.6. With ISO performance increasing with every generation, the ability to use f/2.8 zooms in very dark environments is becoming more of a reality. In those conditions, visualizing focus is still important, but so is a bright viewfinder.

  1. Measurements were made by metering the viewfinder with a second camera.

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