35mm SLR with differently placed microprisms?

pulatom · Joined: 01 Dec 2010 Posts: 109 Location: Wroclaw, Poland

All the SLR's I've known so far have the microprism in the center of the frame. This forces me to recompose after focusing so I won't waste the frame area by cropping. But this causes a problem with loss of focus, I seldom get an unsharp image if I keep the main subject in the center of the frame, but after recomposing the focus goes far below the acceptable level (we're talking about shooting wide open ofc Razz

). I don't know if it's caused by the curvature of field or loss of the edge resolution, but I've seen many photos with, let's say, Jupiter 9 or Helios 40, that are shoot wide open and are pretty sharp even if the subject's eyes are far from the center. I bet they're made with a DSLR that has more focus confirmation points and there's no need to recompose before relasing the shutter.
I wonder if there's a full manual 35mm SLR (old Praktica MTL like) that has differently placed microprisms, on the Golden Rule lines' crossings for example? I think it would help a lot in making a sharp portrait photos wide open Smile

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RioRico · Posted: Thu May 19, 2011 2:22 pm Post subject:

The only 35mm SLR I know with nonstandard VF is the Olumpus Pen-FT half-frame, with a vertical porroprism. But that doesn't really address your question. Maybe you're thinking of focusing screens? I think KatzEye will custom-cut screens, so you could possibly get a screen with focus zones set in halves or thirds or whatever. That's the best I can think of.

Nesster · Expire: 2014-02-20

A good, contrasty and reasonably bright ground glass is very effective for focusing on a film SLR. Some cameras have better ground glass than others - and it's not always the same as a large or bright viewfinder, it has more to do with how effectively the glass snaps into focus.

Among Pentaxes the KX has a very effective vf, better than the later, brighter screens. I also like the screen on the Yashica TL Electro-X - I focus using the ground glass area all the time with this camera.

pulatom · Joined: 01 Dec 2010 Posts: 109 Location: Wroclaw, Poland

I think a good plain matte screen would be probably good (it works great in Pentacon Six), but in majority of modern cameras there's a Fresnel lens that makes focusing outside the central spot almost impossible Sad

. Looks like I have to look for some custom made focusing screen or use the medium format exclusively Razz

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iangreenhalgh1 · Expire: 2014-01-07

cooltouch · Joined: 15 Jan 2009 Posts: 9096 Location: Houston, Texas

Shortly after I bought a 600mm f/8 mirror lens back 1984, I started looking around for plain matte solutions to focusing because of what an f/8 optic does to microprisms and the half-circle aids. So I've been using plain matte screens since then, and once I got used to them, I found that I preferred them over screens with focusing aids. A good matte, or plain ground glass screen, should do what you need, I'm thinking. But then I don't understand why the subject should be out of focus if you prefocus on it then recompose unless the lens's resolution falls off severely toward the edges. I'm assuming manual focus, of course.