Viewfinder Markings

The standard Katz Eye™ screen for the Pentax K10D/K20D does not have the focus area brackets marked like the original screen - we prefer the clean look on the screen. For those users that wish to have the focus area brackets marked, this is available as an option. If you want the AF area markings, please be sure to select the focus area bracket pattern when adding the screen to your cart. The original spot metering arcs cannot be shown due to their coincidence with the prism, but that area corresponds roughly to the diameter of the split prism. All other viewfinder information is unaffected by the installation of the Katz Eye™ screen and the red AF indicator squares light in the normal fashion.

Metering Information

Because of the presence of the prisms, the Katz Eye™ focusing screen for the Pentax K10D/K20D will have some effect on the camera’s light metering. Test results for each of the three metering modes are as follows:

• Center Weighted Average (CWA) Metering Mode: Our testing showed CWA metering mode to be accurate for all AF lenses having a maximum aperture of f5.6 or larger (lower f number).
• Multi-segment Metering Mode: Our testing showed evaluative metering mode to be accurate for all AF lenses having a maximum aperture of f5.6 or larger (lower f number).
• Spot Metering Mode: Our testing showed spot metering mode to be within factory tolerance for all AF 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 with lenses slower than f2.0. 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.

Please note that Katz Eye testing was performed on the K10D and while it is expected that the K20D results will be similar, K20D users are strongly advised to confirm metering results with a test photo prior to beginning critical work.

The “Plus” Prism

The Katz Eye™ focusing screen for the Pentax K10D/K20D is 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

Since the Pentax K10D and K20D were designed with user-changeable focusing screens, installation is very straightforward and a suitable installation tool will be included with your purchase. No modifications or calibration are required. The installation procedure is identical to the procedure to install the replacement screens sold by Pentax. You may use Pentax’s instructions if you have them available or you may use the Katz Eye™ Optics instructions which are available here.

If you don’t feel confident installing the Katz Eye™ screen, your local camera shop should be able do it 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 can, though it’s not the normal procedure. 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

Like all screens made by Katz Eye™ Optics, the Pentax K10D/K20D screen can be OptiBrite brightness enhanced for the ultimate appearance. The OptiBrite treatment showed no effect on the light metering of the K10D in our testing. Click here for more information about the OptiBrite treatment.

Composition Aids

In addition to the AF area brackets, the Katz Eye™ focusing screen for the Pentax K10D/K20D is available with optional guide patterns to aid in proper composition. We have a variety of standard patterns of gridlines and croplines available or we can provide a custom pattern to your design. Click here for more information about our gridline and cropline patterns. Please note, that if you choose the AF Area Brackets AND an additional composition aid pattern, the two will be combined in an aesthetically pleasing way and will appear different than the drawings shown.