Focusing Systems

Hi,

I have an 35mm SLR with microprism focusing screen, and i was curious about the split-screen type, because never seen one of them. How are they like? How is the focusing process like with them?

Another one: auto focus SLRs still has the focusing aids, or you must focus only 'by eye' in manual mode? What about digital SLRs?

Thank you. I hope my english isn't too bad... :)

I used to have a manual-focus SLR with split-screen (I forget which one). It worked fine. I can't say I really found it better than microprisms.

On my Nikon F100 in manual focus mode then in the information panel at the bottom of the viewfinder you have a couple of arrows telling you which way to turn the focussing ring plus a dot in the middle that lights up when you're in focus. On the F75 you only have the dot. If I was doing manual focussing then I would prefer the F100 because the viewfinder is brighter and larger.

Charles

For manual focusing, I prefer split image over microprism because it's easier to see against most subjects. The split might be horizontal, vertical or diagonal which I think would be best. Basically how it works is that in the split portion of the screen (small circle in the center), you'll see something - say a fence post - cut in two halves. In the case of a horizontal split image screen, the top will be towards the left (or maybe it's right) of where it actually is, and the bottom will be opposite. Line up the two halves and you're in focus.

It's possible to change the focusing screen on some cameras, but not all. What camera do you have?

I've got an F100 and a Fuji S2 which is built on a Nikon N80. That camera just has the dot as Charles describes too, and it's not so easy to manually focus because of that and the relatively small viewfinder image (due to the 1.5 crop factor). Since the Kodak and the Nikon D100 are built on an N80 I'm sure they just have the "dot" too. I prefer to use fast lenses and only autofocus with it, but I'm sure other cameras work differently.

There is no one perfect focusing screen that works best with ALL subjects.

As the others have pointed out, the split-screen type works great with solid lines or edges. This can be just about anything. Poles, trees, horizons, doorways, neckties, you get the idea.

When you have a more abstract subject with little or no clean edges, the split-sceen loses much of its advantage, as there may be nothing to line up. This is when a microprism screen would probably work better, as you simply use your eye to choose the sharpest focus in the viewfinder.

I always liked the hybrid screen best, with a split-screen center spot, and a microprism around it. I simply use what works best for the situation...

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Originally Posted by Norfindel

Hi,

I have an 35mm SLR with microprism focusing screen, and i was curious about the split-screen type, because never seen one of them. How are they like? How is the focusing process like with them?

Another one: auto focus SLRs still has the focusing aids, or you must focus only 'by eye' in manual mode? What about digital SLRs?

Thank you. I hope my english isn't too bad... :)

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Thank you, i understand now how it works. Seems like split-screen is better for most situations. I find my focusing screen to be a bit difficult to use on low light.
I have an zenit 12xp, and the focusing screen is fixed (hey!, but at least, with this camera i don't need to worry about battery life :) ).