Viewfinder Markings

The Katz Eye™ focusing screen for the Canon 40D 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 Katz Eye screen. No changes will occur.

Metering Information

The Katz Eye™ focusing screen for the Canon 40D 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.

The “Plus” Prism

The Katz Eye™ focusing screen for the Canon 40D is available exclusively in the Katz Eye™ “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 Katz Eye™ “Plus”. More information about the Katz Eye™ “Plus” can be found here.

Installation

The Katz Eye™ screen is a direct replacement for the original and no modifications to the camera are required. Since the Canon 40D focusing screen is 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 and the link will be included with your purchase.

If you don’t feel confident installing the Katz Eye screen, your local camera shop should be able to complete the installation for you. Since the Katz Eye 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 Katz Eye Optics, we would be happy to do so. Please see the Installation Service page to order installation with your focusing screen. Installation service at Katz Eye™ Optics costs $65, plus the cost of return shipping of your camera.

Brightness Enhancement

The standard Canon 40D 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 Katz Eye™ screen is optimized for manual focus applications and has a much improved matte surface. The matte surface on the Katz Eye™ screen is designed to give excellent DOF indication and a very sharp ‘snap’. However, because of this, the standard Katz Eye™ screen for the 40D 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 OpitBrite treatment, the brightness of the Katz Eye™ screen is comparable to the standard Canon Ef-A screen. The OptiBrite treatment affects only the matte portion of the screen; it had no effect on the prism and the OptiBrite treatment will have no significant effect on light metering in the 40D. Click here for more information about the OptiBrite treatment.

Grid/Crop Lines

All Katz Eye™ focusing screens are available with grid patterns or crop lines. We have a variety of standard patterns available or we can provide a custom pattern to your design. Click here for more information about our grid/crop line patterns.