Adjusting the Rangefinder on a Seagull 203-I

I recently got a Seagull 203-I, a Chinese-made medium format folding camera with a coupled rangefinder. I haven’t seen results out of it yet, but I’m excited to use it. It takes a special occasion to get me out of the house with a camera larger than jacket pocket size, so something that just barely crams into a men’s jeans butt pocket (ymmv) and offers some focus assurance is a great combo for me.

Of course, that rangefinder won’t help me to nail focus if it’s not adjusted properly. I didn’t find existing instructions online for setting the horizontal alignment of a Seagull 203 rangefinder, but with no other option I managed to figure it out myself, so here’s a brief account of how I did it. Again, I’m working with a Seagull 203-I, a later model with a flash hotshoe and a shutter without EV coupling. Seagull 203 cameras of one stripe or another seem to have been made from about the 1960’s into the 1990’s, but I haven’t heard of any particular changes to the rangefinder coupling during that time, so odds are this should also work for other variants.

Open the folding shutter door, and look at the camera straight-on below the shutter apparatus. You should see a cylindrical flathead screw. As you turn the focus wheel, a specially shaped side of it pushes that screw more or less; I’m not a mechanical engineer, but I believe this arrangement makes the focus wheel a cam, and the screw a cam follower. A spring pulls up the lever the screw is attached to, so that it properly follows the cam. The level that’s moved by the cam follower screw pushes down another lever at a right angle to it. This lever, which runs from about the back end of the shutter into the camera body, is part of additional linkages that transmit that motion to the rangefinder mirror.

OK, so that’s roughly how it works, let’s get down to aligning. Set the focus to infinity and look through the rangefinder at something very far away. If you’re reading this, then probably the double-image isn’t quite lined up. Now look at that screw again and see if you notice anything. Perhaps you noticed an irregularly shaped collar around the base of the screwhead? That’s right, fire up the old Xzibit memes, because your Seagull heard you loved cams, and got you a cam for your cam follower. Adjust that screw (a *tiny* amount) and that collar will nudge the lever up or down a smidge in relation to the cam follower screw head. For me, turning the screw a bit counter-clockwise nudged the ghost image to the left.

That’s it! I hope this helped. A couple notes here at the end, though:

  • That screw only adjusts the horizontal alignment. The vertical alignment of my rangefinder is also a bit off, but not so much that I feel like removing the top plate to deal with it.
  • If you adjust your rangefinder, use it properly, and still end up with out-of-focus pictures, your problem may be with your lens. Basically, that it’s not actually focused to infinity when the focus wheel says it is. The process to fix this is called collimating the lens.

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