The 1N's focusing screen is noticeably darker than the EOS 3. The screens are very dense-matte:this makes determination of depth of field precise, but at the expense of illumination. The 3 has 8 different types of screen available; go to a Dealer who will permit you to change through a couple to see if a change provides any improvement. Likewise, the EOS 1N has a stable of screens to change over too, so a bit of experimenting and comparison is in order rather than jump from one camera to another. Mind you, the 1N has firepower where the 3 does not, and it would be (is) my tool of choice. Biased, aint I!?