If you’ve never shot with an old manual focus film SLR, you’ve probably never experienced the joys (and pains) of focusing with a split screen and microprism ring. YouTube user ttcalan created this short video that demonstrates how the system looks and works. He writes,
Just a demonstration of how manual focus works on a Minolta X-700. It’s shot through the viewfinder and shows how the split prism and microprism ring help the photographer focus. I also show how stopping down the lens causes the split prism to go dark.
Here’s what Wikipedia says about the system:
The most common type of focusing screen in non-autofocus 35 mm SLR cameras is the split screen and microprism ring variation that aids focusing and became standard in the 1980s. The microprism ring blurs the image unless the lens setting is in focus, the split screen shows part of the image split in two pieces. When both pieces are aligned the setting is in focus. The drawback is that the prisms have considerable light loss, making low-light focusing almost impossible.
When autofocus crashed the photography party, these focusing screens were replaced with simple screens and AF points.
from PetaPixel http://www.petapixel.com/2013/01/02/a-demo-of-split-screen-and-microprism-ring-focusing-in-old-slrs/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+PetaPixel+%28PetaPixel%29