Katz Eye™ Focusing Screen
for the Nikon D200
(Note: this post will be of interest only to camera geeks)
Continuing in the series on the camera toys I've picked up on this trip to The States (other entries: GPS unit, tripod), this post is about the Katz Eye Focusing Screen that I picked up for my Nikon D200.
An SLR's focusing screen is a frosted piece of glass that you're actually looking at when you look through the viewfinder, upon which the lens projects the scene being viewed by the camera.
Katz Eye Optics is a company that makes replacement focusing screens for all kinds of cameras. (They're owned by a family whose last name is “Katz,” so I think the name is quite witty.)
The stock Nikon focusing screen is apparently designed with autofocus in mind, because it's not particularly suited for use when manually focusing the lens. For marketing and technological reasons that I don't quite understand, the stock Nikon focusing screen leaves ample room for improvement, which the $95 Katz Eye provides:
The Katz Eye adds a split-image prism harking back to the SLRs of old. A split circle in the center of the screen, the image in the two halves are shifted away from center until the item in the center is in focus, at which point the two halves become one.
If you've never used one of these, you're in for a treat the first time you're faced with one of the many situations where it's useful (in particular, where there are vertical lines of contrast near the center of the scene that can bisect where the two semicircles join). With it, you can achieve perfect focus.
Outside the split-image prism is a doughnut-shaped area of microprisms, shown as a thick dark ring in the photo above. Like the split-image prism pair of half circles, the image in this area looks normal when the subject is in focus, but when focus is lost, areas of contrast quickly become a jagged patterned field that looks sort of like a closeup of an old halftone newspaper photo.
The microprism section is extremely sensitive to proper focus, so it's with this that you can achieve the most perfect focus. Even the slightest hint of movement in the focus ring turns the microprism area from a clean image to jaggies, so if you see the clean image, you know that the focus is perfect.
Finally, the entire screen shows “focus snap” much better than the stock screen. It's much easier to judge proper focus just by looking at the image on the whole screen.
(For the same reason, it's also said to render the depth-of-field better, but I haven't yet played with that much.)
The Katz Eye in Action
I love it.
I thought I'd love it for the split-image prism, which I had on my first SLR 20+ years ago, but it's turned out that I don't really use that very much because the microprism is so much easier for most situations. Especially when I have the luxury of time to focus, the microprisms give me exceptional confidence with manual focus.
When the situation doesn't allow a lot of time to focus (such as with birds and kids), I find the enhanced “focus snap” of the entire screen to be the best way for me to get focus quickly: I simply adjust focus until the subject looks sharp.
I still use autofocus for a lot of things, especially when I have a lot of light and can use a smaller aperture (such as with most shots of the fallen tree the other day).
Katz Eye offers an optional “OptiBrite” treatment to its focus screens which, for $55 extra, aims to make for a brighter image in the viewfinder, at the expense of some focus snap. This would be appealing with slow lenses (lenses whose minimum f-number is large, such as 5.6 or more) because they don't let in as much light as a faster lenses.
With my lenses, the standard Katz Eye seems as bright as the stock Nikon screen, and I'm very happy with it as is.
If you're thinking of getting one, there are many discussion threads about them, such as this one that contains a lively discussion of the pros and cons. One con is that the new screen can effect exposure metering in one specific case: when the camera is in single-point metering mode, and the center point has been selected.
This is not a mode that the beginning photographer is likely to use very often, but it becomes a useful tool once you're comfortable with the different metering modes. One of the posts in the discussion just referenced is one guy's report on metering in that mode with his Katz Eye, and is a useful read.
I received my Katz Eye a few days after I arrived from Japan, and while the installation is supposed to be simple, I opted to stop by a local camera shop and have it installed because the installation involves sticking tools inside the camera and I was traveling and away from the mental comfort of my own work area. They'd never done one of these, but knew their cameras and did it without incident for twenty bucks.
However, I later noticed that the circle on the screen was not perfectly centered over the center auto-focus-selector point, and once I noticed, it drove me batty. So, I decided to go in and fix it myself.
Using the verbose installation instructions that comes with the Katz Eye, I found so extremely simple that I felt embarrassed for not having done it by myself in the first place. Should I ever need to do it again, I can now swap the focusing screen in, literally, 20 seconds from start to finish. Well, almost....
It's surprisingly difficult get the screen centered properly because there's some side-to-side play in the camera's screen cradle, and the slightest sliver of misplacement shows up quite noticeably as a misalignment when viewing through the viewfinder. Thus, the desire for accurate centering can turn a quick install into somewhat more of a production, as I'll write about below....
My Katz Eye Install Hints
(These hints will make the most sense once you've seen the Katz Eye instructions.)
After removing the lens and placing the camera lens-mount-up on the table, I placed a lens-cleaning cloth over the mirror, to provide a bit of protection “just in case.” I used a Sputz, another of my new toys.
To clip and unclip the focusing screen's small retaining wire, rather than a small screwdriver that the instructions recommend, I used what turned out to be a cuticle trimmer. I found it lying around the house and thought it'd be perfect for controlling the retaining wire because it has a head that sort of resembles a flat-head screwdriver with a center notch. I had no idea at the time what it actually was, but it turned out to be perfect.
This online store is selling what looks to be exactly what I used, two for $5.
While working the wire (clipping or unclipping), rest the thumb of your free hand across the bottom of the lens mount, then rest the tool (cuticle trimmer or screwdriver) on your thumb with a fair amount of pressure such that the tool's movement is just a rocking that pivots on your thumb. This effectively removes much of the worry about slipping (which could easily cause you to scratch the focus screen).
After placing the screen, but before resetting the retaining wire, carefully lift the camera so that you can look through the viewfinder at a bright wall/ceiling so that you can judge whether the screen is properly centered. While doing this, you have to be careful not to rotate the camera too far toward the vertical, or else the un-retained screen will flop out. I found it easier to hold the camera mostly upside-down when doing this.
If you see that the centering is not perfect, lightly tap the camera with one hand to nudge the screen a bit. It can be very touchy, so may require a few back-and-forth taps.
Once you think it's perfect, carefully put the camera body back down and reaffix the retaining wire. It's really easy to nudge the screen out of alignment when you do this, so you may have to repeat this step over and over again until you get it aligned to your liking.
When reclipping the retaining wire, don't worry if it doesn't catch right away. While futzing with the alignment, I clipped and unclipped the wire dozens of times, and even after that much practice, there were times when it would take me quite a while (30 seconds of frustration) to get the clip to catch. Sometimes, it took one second. I don't know what I was doing differently to cause such a difference.
From start to finish, it took perhaps 10 minutes for me to get comfortable with what I was doing and get the alignment perfect.
Because I'd had the lens off for so long and was working around the lens mount, after I was done I did a simple test for dust on the camera's sensor. There was quite a bit (which may have been there before; I don't know), so I cleaned the sensor, and then I was done.