This step-up ring allows non-SLR digital cameras with 49mm filter size specifications to be used with the TSN-DA1 or TSN-VA1 non-SLR camera adapters, which are of course used with Kowa's 60mm, 66mm or 82mm spotting scopes. When employing the TSN-DA1 adapter, you will need to use a spotting scope eyepiece. The TSN-VA1 has an integrated eyepiece within, and thus is used without an eyepiece.
This step-up ring is only intended for digiscoping use. Additionally, you will need to purchase the #DA1AR52 52mm adapter ring(B&H code "KOAR52").