Telescope camera T2 to Pentax M42 lens adapter

prusaprinters

<p>Fitting a fast camera lens to a sensitive astronomy camera gives you the ability to take deep wide field images for spotting meteors, asteroids and satellites.<br/> This adapter permits lenses with a Pentax M42 screw thread (easily available on online auction) to be fitted to cameras with T2 mounting threads.<br/> The M42 camera lens has a focal distance of 45.46mm from the back of the lens to the imaging chip. My Atik 414EX has a back-focus of 13mm from the T2 ring to the imaging chip therefore my "out of the box" STL file prints an adapter which is 45.46mm minus 13mm = 32.46mm tall. This will be okay for you if your camera has a back-focus of 12mm to 13mm(maximum) otherwise you will not get good focus.</p> <p>The many available astronomy cameras have different back-focus lengths. If you have an accessory such as a filter wheel in the system then this increases the permutations. I therefore include the pre-assembly Blender file so that you can build your own custom adapter. What fun!</p> <p>To build an adapter to your requirements, install Blender v3.80 (or later) and open the T2M42atapter_pre_assembly.blend file.<br/> Select menu View | Front (or press number [1] key on the keypad) to view the model from the front against the measuring grid.<br/> The top object is the 0.75mm T2 thread. The middle object is the 21mm radius cutting tool to hollow out your adapter and the bottom object is the 1mm M42 thread.</p> <ol> <li>Press [Shift] + [A] to popup the Add menu. Select Mesh | Cylinder.</li> <li>Immediately click the drop-down which says "Add Cylinder" at the bottom left (see screen shot). Vertices can be set at the default 32 or modified depending on whether you prefer round or chunky. Set Radius to 24mm to give a 3mm wall thickness. The height should be calculated according to your camera back-focus and any accessories, as I have explained above for my Atik example (45.46mm minus camera back-focus minus depth of your filter wheel or accessories = Cylinder height).</li> <li>Select the Cylinder that you created. In the tool window at the bottom-right select Modifiers | Add Modifier | Boolean. Select cutting_tool as the Object in the Modifier and click "Apply". (see screen-shot) This will hollow out the Cylinder.</li> <li>Select the cutting_tool in the object tree (top-right), then right-click and select Delete as it is no longer required.</li> <li>Select the M42 thread (the bottom object) and drag it up using the blue arrow to be completely inside and flush with the bottom of your adapter (Cylinder). With the M42 thread selected, [Shift] + click the Cylinder so that both objects are selected. Right-click and select Join.</li> <li>Select the T2 thread (the top object) and drag it down using the blue arrow to be inside the top of your adapter (Cylinder). Have the actual threads showing above the top of the Cylinder. The design allows for 4mm of threads above the top of the adapter however your camera (or filter wheel) may not have sufficient recess to take this. If the recess is less then slide the T2 thread object further inside the Cylinder to reduce the amount of thread showing above the adapter. Use the background 1mm grid to measure the height of threads showing. </li> <li>Select the T2 thread and [Shift] + click the Cylinder so that both objects are selected. Right-click and select Join.</li> <li>You should now have just one object left - your finished adapter! Drag it around using your mouse with the middle button (wheel) pressed to check that it looks as expected (see screen shot)</li> <li>Export as a STL file (or your preferred format) for slicing. Whatever colour you print the adapter, I suggest painting the inside matt black to reduce reflections.</li> </ol> Category: Physics & Astronomy