Adjustable length of the grate one may move focal length by 45 mm with relation to the mirror. Such a solution allows for taking photos in so-called main focal length of a telescope. By mounting a photo camera instead of mirror, with the shortened grate, one will obtain the same effective focal length as for the given telescope. Distance rings made of anodised aluminium and A2 stainless steel. The M6 thread made of brass, preventing possible stuck of the screw.
If you would like to reshape grate of your telescope or you are in need for distance rings please contact us. We provide size 6 and 8 pipe grates for any given measurement.