Focusing Screen Question


TPF Noob!
Apr 10, 2013
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Hi all! I had a focusing question that I'm hoping someone could answer for me. Right now I shoot with the Canon Rebel t4 with the 85mm 1.2 glass on it(probably counterintuitive being on a low end camera, but at the time, I'd rather spend the money on the lens rather than the camera for right now)..Anyways, like most 85mm, focusing is a challenge and not for the faint of heart. However, I have heard that on top of shooting on MF rather than AF with this lens, I should purchase a new focusing screen for the camera? These are rather inexpensive, but I was just wondering if anybody had any insight on this? Should I get it? does it help a lot? Thank you!
Where did you get the idea that focusing is one a challenge and two not for the faint of heart? Focusing like everything else takes a degree of understanding your equipment and the situation and choosing the best option to achieve the objective. Perhaps if you posted photos of some of the trouble issues you are having it would help.
I just meant that it is a beautiful lens that produces beautiful results, but even in the best circumstances, I have found it to be a little bit challenging. I understand light, camera shake, shooting wide open will cause focus issues, etc, but to maximize my photos, I had heard that focusing screens are helpful.
Are you mainly use manual focus instead of autofocus?
I'd say I use it 75% of the time, depending on the situation. I'd ideally like to use it all the time, since I find it focuses more clear than AF, but with quick moving kids, I'll use AF. :)
Do you have any experience with KatzEye? Thanks!

I have one in my D7000. If they made one for my D600, I'd order one so fast my credit card would melt.
I have one in my D200. Brilliant device. Haven't gone for one in the D800 yet because of the phenomenal AF system. But if I did want a split prisim again I would go for another Katzeye Optics one.
Well... I guess an old dog can learn a new trick. I wasn't aware that changing a focusing screen in a modern DSLR was so simple; I assumed since the pentaprism was not removable as it was in some of the pro level film bodies such as my F5, the only option was one of those adhesive screens stuck on the underside. Thanks Buck for catching that! These do indeed look like a trick little gizmo.
The problem with focusing screens designed for AF cameras is the way the screens are optimized. AF screens are designed for clear, bright viewing, and have a very smooth texture to their grind. The practical effect is that the depth of field shown does NOT, I repeat, DOES NOT, represent the shallow depth of field of apertures that are physically wider than about f/4.5 or thereabouts. So, wide-aperture lenses which have very shallow depth of field, and which need critical, spot-on focusing, are actually somewhat handicapped when the shooter tries to manually focus them using a screen that is optimizwed to be bright, clear, and easy to view.

The problem of manually focusing AF lenses is even worse on crop-body cameras, since the image is small, and many lower-end bodies use pentamirror instead of pentaprism systems, and the overall through-the-camera viewing experience on the intro level bodies is pretty far from what it is on the flagship-end bodies. With my glasses and my vision, I find the low-end Nikon and Canon bodies and their viewfinders absolutely abysmal. Offsetting that is the fact that the mid-level bodies and up now offer live view, with instant zoom-in, and so on. Still, many AF lenses have VERY short manual focusing throws, which can make it difficult to hit the exact, precise distance needed when a creaky old human is doing the focusing,m and not a modern, high-speed, computer-driven mechanism.

Anyway...a manual focusing screen WILL look a bit dimmer, and coarser, but will offer more contrast, and will show more-accurate depth of field, that is much closer to what a wide-aperture lens will show, due to a different degree of "scatter", which is determined by how the viewfinder screen is designed and made. Different viewing screen types often require an exposure "offset" to be entered, to compensate for different screen brightnesses that deviate from the expected normal screen's baseline. My guess is that the OP might have better luck, better results, focusing an 85/1.2-L using the Rebel's AF system. The lens is optimized for AF, and the camera is too.
If you're having a difficult time getting focused properly on the 85mm, is it because you're shooting at f/1.2 all the time?
So it doesn't mess with the AF at all? I think I heard that somewhere.

Not the KatzEyes. They do, however, affect spot metering to some degree.

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