Viewfinder Markings

The KatzEye™ focusing screen for the Canon 40D and 50D has no effect on existing viewfinder information. All active viewfinder information, including the focusing points will still function normally.

Live View Mode

Live View mode continues to function normally with the installation of the KatzEye screen. No changes will occur.

Metering Information

The KatzEye™ focusing screen for the Canon 40D and 50D has little to no effect on light metering in Evaluative or Center Weighted metering modes. Partial and Spot metering modes are somewhat more affected, depending on conditions. We recommend use of the Ef-A selection in the camera’s focusing screen type custom function for most accurate results. Please see your owner’s manual for instructions on adjusting the custom function settings. Detailed test results for each of the four metering modes are as follows*:

• Evaluative Metering Mode: Our testing showed evaluative mode to be within factory tolerance for all lenses having a maximum aperture of f4.5 or larger (lower f number). AF lenses with a maximum aperture of f5.6 or slower (higher f number) will overexpose slightly. With an f5.6 AF lens, we recommend an exposure compensation of -2/3EV. Manual (non-CPU) lenses with a maximum aperture of f5.6 or slower (higher f number) will underexpose slightly. With an f5.6 non-CPU lens, we recommend an exposure compensation of +2/3EV.
• Center Weighted Average (CWA) Metering Mode: Our testing showed CWA metering mode to be within factory tolerance for all lenses having a maximum aperture of f4.5 or larger (lower f number). Lenses with a maximum aperture of f5.6 or slower (higher f number) will underexpose very slightly. With an f5.6 lens, we recommend an exposure compensation of +1/3EV.
• Partial Metering Mode: Our testing showed partial metering mode to be within factory tolerance for all lenses having a maximum aperture of f2.0 or larger (lower f number). Lenses having a maximum aperture smaller than f2.0 (lager f number) will show a shift toward increased exposure. The shift will be greater for lenses with smaller maximum apertures. When using partial metering mode, it is advisable to first take a test shot, check the histogram, and adjust exposure compensation as required. Starting points for exposure compensation are as follows: f2.8 lens: -1/3EV, f4.0 lens: -2/3EV, f5.6 lens: -1EV.
• Spot Metering Mode: Our testing showed spot metering mode to be within factory tolerance for all lenses having a maximum aperture of f2.0 or larger (lower f number). Lenses having a maximum aperture smaller than f2.0 (lager f number) will show a significant shift toward increased exposure, with the shift increasing for lenses with smaller maximum apertures. Spot metering mode is not recommended when using a split prism focusing screen except with very fast prime lenses. However, if spot mode must be used, it is strongly advised to first take a test shot, check the histogram, and adjust exposure compensation as required.

* Note: Metering test results presented are based on testing of the 40D model. While results are expected to be similar for the 50D, users of this model are strongly encouraged to take a test shot and check the histogram before beginning any critical shooting.

The “Plus” Prism

The KatzEye™ focusing screen for the Canon 40D and 50D is available exclusively in the KatzEye™ “Plus” version. The “Plus” version has a unique prism design which delays the prism ‘blackout’ phenomenon until well after f11. Ordinary split prisms will black out by about f5.6, rendering them difficult to use with slower zoom lenses, teleconverters, or in extreme macro photography... but not the KatzEye™ “Plus”. More information about the KatzEye™ “Plus” can be found here.

Installation

The KatzEye™ screen is a direct replacement for the original and no modifications to the camera are required. Since the Canon 40D and 50D focusing screens are designed to be user changeable, the process is quite straightforward and a suitable installation tool will be included with your purchase. Nonetheless, if you are not confident in your vision or dexterity, professional installation might still be advisable. For those users installing the screen themselves, a detailed installation guide, with plenty of high resolution photos, is available for download here.

If you don’t feel confident installing the KatzEye screen, your local camera shop should be able to complete the installation for you. Since the KatzEye screen is a direct replacement for the original, any competent shop should be able to handle the installation and the original screen can be reinstalled at any time, should you so desire. If you want us to install it at KatzEye Optics, we would be happy to do so. Please see the Installation Service page to order installation with your focusing screen. Installation service at KatzEye™ Optics costs $65, plus the cost of return shipping of your camera.

Brightness Enhancement

The standard Canon 40D/50D screen (type Ef-A) is optimized for automatic focusing. As such, it is very bright, but it gives a very poor indication of DOF and has very little ‘snap’ (indication of when focus is achieved). The KatzEye™ screen is optimized for manual focus applications and has a much improved matte surface. The matte surface on the KatzEye™ screen is designed to give excellent DOF indication and a very sharp ‘snap’. However, because of this, the standard KatzEye™ screen for the 40D and 50D is slightly darker than the standard Canon Ef-A screen, particularly at smaller apertures. If viewfinder brightness is a concern for you, consider the optional OptiBrite enhancement. With the OptiBrite treatment, the brightness of the KatzEye™ screen is comparable to the standard Canon Ef-A screen. The OptiBrite treatment affects only the matte portion of the screen; it has no effect on the prism and the OptiBrite treatment will have no significant effect on light metering in the 40D/50D. Click here for more information about the OptiBrite treatment.

Composition Aids

All KatzEye™ focusing screens are available with optional guide patterns to aid in proper composition. We have a variety of standard patterns of grid lines and crop guides available or we can provide a custom pattern to your design. Click here for more information about our composition aid patterns.