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View Full Version : Accessories Haoda split-prism focusing screen for E-1



bg2b
04-20-2008, 11:01 AM
I wanted a split-prism screen for use with my E-1. I considered ordering a Katz Eye screen, but wasn't overly happy with the metering results various people have reported. So I decided to play guinea pig and take a chance on the Haoda screen. I paid $72 plus $5 shipping for the screen. The maker acknowledged receipt of payment immediately and told me when the screen would be sent. A couple of days later, I got another email that the screen had been mailed. There were a total of six days from order to arrival of the screen.

Included in the package was the screen, some tweezers, a toothpick-like tool, some rubber glove-like things for your fingertips and two strips that I eventually discovered to be shims. There were no instructions, but I knew approximately what to do from having installed the Olympus FS-2 screen. I have the Olympus tweezer-like tool from the FS-2, and I used that to install the Haoda screen, ignoring everything else for the moment. The tab for grasping the screen is a bit smaller and harder to catch than the one on the original FS-1 screen and on the FS-2, but it's not really an issue.

The screen has no markings at all, just a central diagonal split prism and a microprism collar around that. The outer edge of the collar is approximately the size of the circle on the regular E-1 screens though, so you can reliably judge the center-weighted metering area and where the side focusing points are.

I first tried some metering tests with all my lenses. Spot metering on the E-1 is unaffected by the screen, so I just pointed the camera at a blank uniformly illuminated wall and cycled through ESP, center-weighted and spot metering, with spot assumed to be correct. Metering is done at maximum aperture with ZD lenses, so that's all that really matters for this test. I tested each lens at minimum and maximum zoom. Here are the metered shutter speeds:

http://www.fourthirdsphoto.com/vbb/attachment.php?attachmentid=8860&d=1208709311
(Sorry, there's an error in the table; in the 85 f4 line, the first 30 should be in the Haoda ESP column. I did that test at the end after realizing that a check at f4 would be useful, and I didn't reinstall the FS-2 to check at that setting.)

The metering seems to depend pretty consistently just on the aperture. At f2.8 and faster, you don't need any compensation. At f3.5, there's a 2/3 stop overexposure. For the 14-54 and 11-22 in dynamic situations, I would probably dial in -1/3 exposure compensation and just leave it there. Then it will be off -1/3 stop at the wide end and +1/3 stop at tele end, but neither is that significant. The old 40-150 is more problematic at full zoom. You'd have to explicitly correct with that lens, or use spot metering. Assuming the 50-200 follows the same pattern as the 14-54 and 11-22, it should be perfectly acceptable. Based on the 40-150 @ 85 result, it appears that by f4, there's a 1 1/3 stop overexposure. So I suspect the 12-60 would be off enough at the tele end that it would need more careful correction. And I would not recommend the screen at all with lenses that have a maximum aperture of f5.6.

An issue with some split-prism screens is black out, where half the prisms turn dark. If you move your head left and right, you can switch which prisms black out, but you might not be able to get both sets of prisms visible at the same time. And if you can't see both sets of prisms at the same time, you can't focus. The Katz Eye is supposedly very good here, being useable beyond f11. I checked the Haoda screen using the depth-of-field preview button. It starts to get a little iffy at f5.6. You can use it there but you have to be careful about your eye position. I don't think it's really useable by f8. This is another reason why I don't recommend the screen with an f5.6 lens.

Finally came the critical focus test. I suspected from the presence of all the extra stuff in the kit that there might be an issue, and sure enough there was. Using the ZD 50 and a focus test chart, I found that in manually focusing, I was consistently front-focused. Using autofocus, the camera was perfect, but the viewfinder indicated a slight but noticeable misfocus.

I was not sure what to do, so I emailed the maker. I got back a quick reply saying:


1. Install the original shim in your camera. 2. If the difference is a lot, you can flip the screen.
That was not overly helpful. I don't think the E-1 has an original shim, though since I bought my camera used, I can't be sure. When I got an FS-2 to replace the original screen, I never noticed one, and I certainly never removed one. Also, because of the tab position on the E-1, it's not possible to install the screen flipped over. The mention of shims was a useful clue however, since I realized that that's what the mysterious strips must be. Since Haoda sells screens for many different cameras, I suspect that the email was a generic response to anyone who complains about misfocus.

I sent another email explaining the above and asking how and where I should install the shims. The reply this time was:


You can apply the stripes to the corners of the screen. To make it more near the mirror (outside)
I didn't find this overly helpful either, and I was getting somewhat discouraged at this point. My inclination was to return the screen, order a Katz Eye, and hope for better luck. However, I decided to sleep on it for a day and think about what to do.

The next morning, I spent some time thinking about the problem. Based on considering the case of a simple lens, I concluded that the screen actually needed to be further away from the mirror to correct front focus. And after studying the holder and the positioning of the screen a bit, I saw that this would be doable if I could somehow get the shims between the face of the screen and the holder. I examined the shims closely, and noticed that there seemed to be some sort of backing attached on one side. That was encouraging, since I figured that they were probably adhesive. Using two pairs of tweezers, I managed to start peeling away the backing and confirm this. The shims are much longer than the screen, and there were two of them, so I wasn't worried about messing one up. I decided to try sticking one piece of shim on each of the two side edges on the bottom of the screen.

Peeling away the backing was a bit tedious. I found it easiest to grasp the shim and backing near the end with one pair of tweezers, grasp the isolated backing with the second tweezers, and pull a bit in the direction of the first tweezers to start separting the backing from the shim. When the separation point reaches the first tweezers, slide them down the shim by another couple of millimeters, and then pull a bit more backing off. This works since the shim is metal and is somewhat stiff. This picture shows how the original shim looks. You can see the isolated backing at the end. The other shim shows the result of carefully peeling the backing away.

http://www.fourthirdsphoto.com/vbb/attachment.php?attachmentid=8862&d=1208709311

Once I got enough of the backing off, I double checked to make sure I was about to place the shim on the bottom of the screen, and then I put the end of the shim at the corner of the screen and carefully aligned it with the edge. Then I used the toothpick-like tool to gently press the shim down. When most of the shim was down, I used a pair of scissors to clip it to the right length, and finally pressed down the last bit. Here's a picture of the screen with the installed shims.

http://www.fourthirdsphoto.com/vbb/attachment.php?attachmentid=8863&d=1208709311

I reinstalled the screen and tried the focus test again. The result: success!

http://www.fourthirdsphoto.com/vbb/attachment.php?attachmentid=8861&d=1208709311

I don't have enough experience with the screen yet to say for sure that I'll always use it, but I'm happy that it works, and it definitely makes manual focusing easier. Here's a little video taken through the E-1 viewfinder:

http://www.davidlong.org/focusing.avi

By the way, I found that manual focus with the E-1 and ZD 50 is very annoying because of the focus-by-wire. The main problem is that there's a sort of creep as you move back and forth past the point of focus. If you start with your hand on one side of the lens and keep rocking the ring, you'll find your hand creeping along and eventually you wind up with your hand on the other side. It makes the physical feel of "too close, too far, back to the middle" not work, because the middle doesn't correspond to whatever it did when you first went past it. Obviously this isn't an issue with legacy lenses, which is the main reason you'd want the screen anyway.

Overall, I would recommend the screen with minor reservations. The effect on metering seems reasonably predictable, and with most of the mid-grade and high-grade lenses, is probably negligable. The exceptions would likely be the ZD 12-60 and the ZD 7-14, or if you make heavy use of the teleconverters. Since I personally don't have any of those, I don't worry about leaving the screen in all the time. I generally use my 40-150 only for trips to the zoo, and in that case, I don't mind switching screens for the trip. I would like to have had the option of getting grid lines on the screen, but I can live without them. The biggest deficiency is the lack of instructions, but I managed, and it's not really too hard.

jebir
04-21-2008, 01:15 AM
A great write-up!

Just for the record, it seems like the Haoda screen gives identical exposure errors as the KEO screen.

Cheers, Jens.

bg2b
04-21-2008, 05:44 AM
Just for the record, it seems like the Haoda screen gives identical exposure errors as the KEO screen.
I wasn't quite sure with all the various permutations of the KEO screen (plus/non-plus and optibrite/non-optibrite), though now I notice that the non-plus version doesn't seem to be available anymore.

Since the metering errors are about the same, then the Haoda screen should be considered a slightly cheaper alternative which unfortunately requires some tedious fiddling with shims. If you want to use slower lenses (or something like the 2x teleconverter), it would be better to get the KEO screen because of the non-blackout, though you have to watch the metering. The other reason to spend for the KEO screen would be if you want grid lines (and are willing to pay the extra charge for them).