Viewfinder Markings The standard KatzEye™ screen for the Samsung GX-20 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 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 KatzEye™ screen and the red AF indicator squares light in the normal fashion.
Metering Information The KatzEye™ focusing screen for the Samsung GX-20 shows only a slight effect on light metering. In our testing, the KatzEye™ screen tested within factory tolerance in nearly all situations. The only exception is when using spot metering with lenses having apertures of f2.8 or smaller. This combination may produce overexposure, so it is advisable to use either center-weighted average metering or multi-segment metering to preserve accurate meter response when using small aperture lenses. In the event that spot metering mode must be used with a small aperture lens, it is advisable to set an appropriate exposure compensation by reading the histogram of a test shot. Approximate exposure compensation values are as follows:
| Aperture | Multi-Segment | Center-Weighted | Spot |
| 1.4 | 0 | 0 | 0 |
| 2.0 | 0 | 0 | 0 |
| 2.8 | 0 | 0 | -1 EV |
| 4.0 | 0 | 0 | -2.0 EV |
| 5.6 | 0 | 0 | NR |
NR = This combination is not recommended. Use an alternate light metering mode or manual exposure settings.
Note: These exposure compensation suggestions are a recommended starting point only and actual results may vary depending on conditions. Users are advised to take a test photo and check the histogram before beginning any critical work. Apertures indicated in the above chart are the lens maximum aperture as indicated on the lens body and are not affected by the actual aperture chosen for a given photo.
The “Plus” Prism The KatzEye™ focusing screen for the Samsung GX-20 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
Since the Samsung GX-20 was 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 Samsung. You may use Samsung’s instructions if you have them available or you may use the KatzEye™ Optics instructions which are available here.
If you do not feel confident installing the KatzEye™ screen, your local camera shop should be able do it 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 more than 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
Like all screens made by KatzEye™ Optics, the Samsung GX-20 screen can be OptiBrite brightness enhanced for the ultimate appearance. The OptiBrite treatment showed no effect on the light metering of the GX-20 in our testing. Click here for more information about the OptiBrite treatment.
Composition Aids
In addition to the AF area brackets, the KatzEye™ focusing screen for the Samsung GX-20 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.
