Hand rolled Vision3 500T film, but I would like to know what is the best ISO to use, 400 or 800, and why?
Does the film have the RemJet anti-halation layer removed? If so, this process effectively increases the sensitivity of the film to ISO 800. (If not, you know this film shouldn't go through a regular C-41 process, right?)
Will you use a 85 filter?
If "none of the above", why not just shoot it at EI 500? If your camera can't set ISO 500, just set the camera to ISO 400 and "underexpose" by 1/3 of a stop. You can use an exposure compensation setting if available, or else just manually set the aperture narrower or shutter speed faster than recommended – the film will get the right exposure.
The Rem-Jet (removable jet black backing) coat is a dispersion of lamp black (soot) in a binder of cellulous acetate phthalate. This binder is an “acid plastic”. It can be softened and washed away using an alkaline solution. Machine processing uses a pre-bath to temporarilly harden the film so it better withstands transport in a fast moving film processor. The pre-bath softens the Rem-Jet and spinning rollers, much like paint rollers scrub off the Rem-Jet.
You can make an alkaline solution and hand buff with a well washed “T” shirt. This can be performed the film has been processed but before drying. Water 27 to 38°C (80 to 100°F) 800 mL 800 mL Borax solution 15 g/L use 20g Sodium Sulfate (Anhydrous) 100 g Sodium Hydroxide 1.0 g Water to make 1 L
The Rem-Jet serves to protect the film from exposure from the rear. Many motion picture cameras with thru-the-lens viewfinders leaked light if the photographer looked away. It serves as an anti-halation backing. It protects the film when large rolls are loaded and unloaded in subdued light.
Does anyone know if removal prayer to exposure has an effect on film speed? If so, why is this?