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It sounds like you're observing the laser etched glass focussing screen. A focusing screen requires a rough surface so an image can be formed for you to view through the viewfinder.

Ground glass used to be used for this purpose but now glass etched in a circular pattern with a laser is used, to improve the brightness of the viewfinder when used with slower lenses. This pattern is probably what you're interpreting as moire.

Here's what a standard DSLR focussing screen looks like close up:

[![][1]][1] [1]: https://web.archive.org/web/20150907092654/http://www.mattgrum.com/experiments/focus_screen_closeup.jpg

It sounds like you're observing the laser etched glass focussing screen. A focusing screen requires a rough surface so an image can be formed for you to view through the viewfinder.

Ground glass used to be used for this purpose but now glass etched in a circular pattern with a laser is used, to improve the brightness of the viewfinder when used with slower lenses. This pattern is probably what you're interpreting as moire.

Here's what a standard DSLR focussing screen looks like close up:

It sounds like you're observing the laser etched glass focussing screen. A focusing screen requires a rough surface so an image can be formed for you to view through the viewfinder.

Ground glass used to be used for this purpose but now glass etched in a circular pattern with a laser is used, to improve the brightness of the viewfinder when used with slower lenses. This pattern is probably what you're interpreting as moire.

Here's what a standard DSLR focussing screen looks like close up:

It sounds like you're observing the laser etched glass focussing screen. A focusing screen requires a rough surface so an image can be formed for you to view through the viewfinder.

Ground glass used to be used for this purpose but now glass etched in a circular pattern with a laser is used, to improve the brightness of the viewfinder when used with slower lenses. This pattern is probably what you're interpreting as moire.

Here's what a standard DSLR focussing screen looks like close up:

[![][1]][1] [1]: https://web.archive.org/web/20150907092654/http://www.mattgrum.com/experiments/focus_screen_closeup.jpg

It sounds like you're observing the laser etched precision glass focussing screen. The focusing screen has a rough surface so an image can be formed for you to view through the viewfinder.

Ground glass used to be used for this purpose but now it's a laser etched glass which sometimes has a circular pattern which is what you're interpreting as moire.

It sounds like you're observing the laser etched glass focussing screen. A focusing screen requires a rough surface so an image can be formed for you to view through the viewfinder.

Ground glass used to be used for this purpose but now glass etched in a circular pattern with a laser is used, to improve the brightness of the viewfinder when used with slower lenses. This pattern is probably what you're interpreting as moire.

Here's what a standard DSLR focussing screen looks like close up: