I concur with coolcolors. You see, simply transferring a Digital8 tape to an SD card and then copying the contents of the SD card to DVD will not create the proper MPEG file format (.vob extension, file sizes no larger than 1GB per file). Nor will simply transferring Digital8 to SD card then copying SD card to DVD result in a proper MPEG-2 file at all. Instead, what is output from Digital8 is DV-AVI (the same format as miniDV), which must be converted to DVD-compatible MPEG-2 format in the DVD authoring program of your choice. And the video must be output either directly to DVD or to a DVD image file in the DVD authoring program itself. Plus, at a bitrate of 25 Mbps CBR, DV-AVI (though still lossy-compressed in a manner similar to, but not directly compatible with, MPEG-2) simply has too high of a bitrate for standard-definition DVD (which is limited to a total maximum peak bitrate - including video, audio, menus and miscellaneous stuff - of 10.08 Mbps).
And even if your program automatically converts DV to MPEG-2 upon transfer to an SD card, the resulting MPEG-2 video is still not compatible with DVD until you transcode that file even further. This is because at 2GB to 4GB per file, the file sizes on a typical SD card are much larger than the 1GB per file limit imposed by DVD-Video. However, you do not have to reduce the video bitrate to fit the video into 1GB of space; the DVD authoring program will automatically split the videos correctly without having to tinker with the bitrate of your choosing.