I could have predicted it…it always happens…but as soon as I “finished” my Solar Projector (https://www.instructables.com/id/Building-a-Solar-Projector/ ), I realized that I still needed to make a few improvements.
First, despite the fact that the projector’s screen was about 8” located down inside the shell of the device, there was still some significant glare when viewing that tended to wash out the “relatively dim” image. I find it quite difficult to resolve small sunspots when there is low contrast particularly if the focus is not exactly right.
Second, I needed some way of holding my camera for taking photos. …So, back to the shop
Step 1: Construction Details
I came up with the idea of adding a removable viewing hood to reduce the glare. Because the viewer basically blocks most of the ambient light by placing his/her face down to the hood, the image has much better contrast. The hood is just slightly smaller than the existing enclosure and “drops into” the viewing port (see Photo #1). The hood’s corners are “notched” to rest on the outside edge of the projector’s enclosure essentially “locking” it in place. While I would have “preferred” that the hood be even taller than I made it, its depth (~7”) was ultimately determined by the material (specifically - ¼” plywood) that I had on hand.
The camera mount plate is made of ¼” plywood and slips down into two slots when that exceptional image appears. The following is a schematic diagram of the hood showing the placement of the camera mounting plate. The plate is also visible in Photo #1
Photo #2 is a shot I took of the hood by itself with the camera mounting plate in place. I regret that the photos don’t show the alignment/locking notches as well as I hoped, but you can see them on the schematic drawing, Photo #1A.
The Camera Mounting Plate slides into a set of slots, on the inside of the hood (See Photo #3). I made two sets of slot pieces and glued them into place after carefully determining their correct position. The slots are positioned so that the center of the camera lens is at the dead center over the projection screen. The width of the slots should be just slightly wider than the thickness of the plate, but not too wide (you want to be able to easily slide the camera into place), but not so widely spaced that the plate is free to move around. The depth of the slots allows the camera to slide in just far enough to leave the shutter release and the viewing window easily accessible. I rounded off the tops of the slides to make it easy to help guide the plate into the slots.
The camera mounting plate is another piece of ¼” plywood (See Photo #4). When the camera is installed in the hood, the camera lens should be centered on the projection screen. I very carefully measured (and subsequently checked and rechecked) the position of the mounting hole for the camera. I used a commercially available plastic knob with ¼”x20 threaded bolt attached. I glued on a small strip of wood along the back of the plate to ensure the correct positioning of the camera.
I also epoxied a ¼”x20 nut to back side of the plate so that I would have somewhere to store the plastic mounting knob when the camera was not mounted on the plate...I tend to lose things like that if they’re not nailed down somewhere. :-) .
Step 2: Mounting the Camera and Using the Projector
Photo #5 shows the camera on the plate.
The camera mounting plate is removed from the hood for normal viewing. When “that perfect shot” is has been achieved, the camera can be slid into place and the image grabbed. Photo #6 shows the camera in place in the hood ready for use. So far this has worked well for me. Sadly, now that the projector is “finished”…I’m sure I’ll find another “feature” or two to add…the Sun has suddenly decided to basically shut down its production of Sunspots for awhile, so there hasn’t been much to look at, or photograph recently. But I am now ready to look for them and take their pictures when they show up :-)