I really didn’t get a chance to break out the plans until last night. I’ve been working on getting wet plate chemicals together, building my darkbox, tripod and designing on a plate holder.
But, a two days before deadline here I am making my first cuts into plywood for my prototype quarter plate camera. I wanted to work on the lens end of the camera first. After the holder, this is the most important part of the camera. This box needs to be perfectly square with parallel sides. Anything less will make for very sloppy movement and possibly introduce light leaks.
The design here is missing a few lines but once they’re broken out and flattened it doesn’ t matter much anyway. Inside the box is a 1/8″ wide, 1/8″ deep groove for the lens board. Once it’s in, it’s in.
And once assembled, here’s how it looks with my 9″ Petzval installed. The Petzval has a flange on the back that allows me to screw into the lens board. Some lenses this old may be missing their flanges and it’s extremely difficult to get one made last time I checked. There are other ways to keep it from falling out if you happen to get one with the flange missing.
To assemble the camera I glued and nailed one side at a time. Checking for square and measurements along the way. When I had a U I slid in the lensboard and placed the last piece.
Next it’s time for the back part. This is the part that slides in and out of the camera increasing and decreasing the distance between the lens and the focal plane. This is how we focus. Now, there is also a rack & pinion gear on the lens that allows us to focus as well but the sliding box gives us much more flexibility.
Here’s a view of the sliding back of the camera. I’m not going to worry about the frame to hold the plate holder, instead just the box on the inside. I check my measurements of the front vs the plans on the screen and we’re perfect. Four squares cut later, sanding and some glue and nails and we have a sliding box back. Enough of a gap for easy sliding and not enough to cause a light leak problem. The inside will be painted black and I may put a strip of felt on the inside just to prevent the wood from scraping against the other wood box.
And here it is, the back is loose and just hanging there. When I add a baseboard and a way to tighten down the position of the sliding box any of that play should disappear. On top is a broken quarter plate ground glass for size reference.. Oh and also for focus checking. 3′ to infinity. That’ll work! And don’t mind the plywood. Because this camera will be used in the field I’m going to paint the outside. Once I verify that this design is how I want to go I’ll cut the next one in hardwood.
And one photo of the view from the back of the ground glass. It’s hard to shoot these on a camera phone!