I am looking for a 105 mmm lens hood -
It would help to know the lens and the diameter.
APO Symmar 300 mm front screw in filter size is 105 mm
With a 'normal' lens shade you may vignette if you are doing any movements (is this for an 8x10 camera?). Most people would use an adjustable compendium.
Or you could use the darkslide that you have in your hand to shade the lens.