2" Filter Drawer for Canon EF Bayonett

thingiverse

This is a filter drawer that allows for quick filter change for astrophotography. I needed it to connect to my coma corrector which has an M54x0.75 metric male thread. For this, I printed an adapter ring. This ring can be cut open (simply use a metal saw) if the printing does not yield results that allow screwing onto the coma corrector due to the very fine threads. Once it is cut open, a thin screw can be used to tighten the adapter ring around the coma corrector (seen in photo). The hole for the screw is already prepared in the adapter_ring. The actual body of the filter drawer then screws on the coarser (easier to print) thread of the adapter ring. It can be secured, if needed, by a set screw. For the set scrrew, a hole needs to be drilled in the conical boss on the side of the body and tapped with an M4 thread (M3 also works). The filter holder itself has a fine thread that accomodates the filter itself. This printed well for me and the filter only needs to screw in enough to be safely secured. The filter holder needs to be glued to a snap ring, that snaps around the body and keeps the filter holder from falling out. Printing the snap ring can be a bit tricky since it needs support and I did not have great results with all support features that my slicer offered. Therefore, I also designed a second version including a support structure. The bayonett for Canon EF on the top is a thin version like this one: https://www.teleskop-express.de/shop/product_info.php/language/en/info/p6527 I printed the body without infill for maximum stiffness which also allowed me to drill holes directly into the body to hold the bayonett ring. The default distance between coma corrector and sensor is 55mm, but I also included a 1mm distance ring that can be placed between the coma corrector and the body to adjust for the right distance to the sensor. The ring thickness can easily be scaled in any slicer for your needs. Since screwing the filter into the printed part is a bit tricky, I would not want to mess with it in the field. Therefore, I recommend printing separate filter holders for each filter you own. In order to properly store those, I included a storage box where you can slide the entire drawer into and it snaps in place. I printed everything in PETG without infill and used 1mm layer hight for the fine threads. It works for me - but use at your own risk! Always make sure the filters are secured tightly so they don't fall out and get damaged. Also, don't overload the thing with super heavy cameras. My EOS 700d is no problem, but I don't know what you are using.