Here are my two modified Nikon Fs. The left hand one has had the mirror box removed and has a leica thread mount. It is used with an external viewfinder with my 15mm Heliar. It is entirely successful and is quieter than my Bessa L. The right hand one is being converted to coupled rangefinder. The rangefinder that I am using is from a Konica Auto S3. I hope to finish it soon.