Canon XSi Viewfinder

Canon XSi Viewfinder

The Canon XSi features a digital SLR design, so the optical viewfinder offers a true, through-the-lens (TTL) display. A dioptric adjustment dial accommodates eyeglass wearers, letting them adjust the viewfinder optics between -3.0 to +1 diopters. Coverage is rated the same as the previous XTi model at 95%, but magnification is higher, at 0.87x for a 50mm lens and -1 diopter, versus the XTi's 0.83x magnification. The viewfinder eyepiece has an eyepoint of approximately 19mm from the eyepiece lens center, a little lower than the XTi's 21mm eyepoint.

A pair of horizontal infrared sensors just below the viewfinder, which we've highlighted with a green rectangle, detect your eye as it approaches the viewfinder, and deactivates the LCD information display if you have the LCD Auto-off option enabled.

Like the Canon XTi, the XSi viewfinder uses a pentamirror design. The advantage of a pentamirror is that it is lighter and less expensive, however an all-glass pentaprism design delivers more light to the viewfinder eyepiece, thanks to its more efficient internal reflection. As a result, the Canon XSi's viewfinder image is not as bright as the EOS 40D, which uses a true pentaprism. However, Canon says they used a more efficient coating on the mirrors in the pentamirror which makes for a brighter image compared to the XTi. Viewfinder blackout has also been improved from 170ms on the XTi to 130ms on the Canon XSi.

The illustration below shows all the elements in the Canon XSi's viewfinder. The extensive information available appears beneath the image area in a small strip, and reports all of the major camera settings, such as shutter speed, aperture, flash mode, EV compensation, etc. Compared to the XTi, the XSI's viewfinder info adds ISO speed (sensitivity), a welcome addition that is even more useful now that there is a dedicated ISO button, and a Black & White mode indicator.