Filters for Telyt 400 and 560
I recently purchased two Telyt-V lens, the 400mm/6.8 and the 560mm/6.8, and could anyone please help me with some details regarding using filters? According to my "Delaney" book, both use a Leica Series 7 size filter in the slot machined into the lens tube behind the aperature diaphram. My questions are, first, is there a holder/adapter involved in securing the filter before placing it into the tube's slot; and, second, what is the physical size of a Series 7 filter if I have to source the item through Tiffen, B&W, or some other manufacturer? Also, would anyone be able to tell me what the physical size of a Leica Series 8.5 filter is?