Tamron 70-200mm F/2.8 Flat image adapter

thingiverse

One of the calibration frames used in astrophotography is called a flat frame. Flat frames are used to tell the image stacking software how to remove vignetting from the image. The most common method for creating flat frames is to cover the lens with two layers of white cloth and take a picture of an evenly illuminated subject (usually a cloudless sky or a tablet with a white screen). It's very important to remove any creases or irregularities in the cloth. I designed this adapter to capture two pieces of cloth and fit snugly over my Tamron 70-200mm F/2.8 lens. The interior diameter of the adapter should fit other lenses that have 88mm barrels. I pressed the sleeve of an old dress shirt between the two rings, then cut off the excess.