The d52 mm light filter is screwed into these same grooves. This must be done carefully, without distortion. It is screwed in a few turns "untightly" but not to the end of the thread. This is quite enough. Everything else has already been said by others.
Discontinued Canon EOS 7D Digital SLR 📷 Camera Body Only with 18 MP CMOS Sensor
88 Review
Nikon D3100 DSLR Camera Body (Kit Box) - No Lens Included, International Version with No Warranty
298 Review
Nikon D5100 Digital SLR Camera with 18-55mm VR Lens - High Resolution 16.2MP
172 Review
Nikon D3100 DSLR Camera with Auto Focus-S Nikkor Zoom Lens (Discontinued by Manufacturer)
109 Review