Przedłużka M48 ze zmienną długością toru optycznego od 23 mm do 31 mm

In special cases, such as when you need to set the correct distance between the camera sensor and a photo corrector (field flattener, coma corrector, or focal reducer), you have to be very precise. If the extension of the right distance is not available, you can use this M48 variable extension ring that can be adjusted at will in a progressive way from 23 to 31mm.