Background:
Exposure Assistant approximates the length of exposure for various B&W films (and some color films) in low light situations. In low light, extra exposure is needed due to reciprocity failure (also known as the Schwarzschild effect). As such, your camera's meter is not accurate in low light. This application approximates the proper exposure time (based upon manufacturers datasheets). A timer is now included in the application. The application warns when the user enters an exposure longer than described in manufacturer's datasheets. Although the exposure in these instances is crudely approximated by mathematical extrapolation, it is crucial that users conduct their own exposure tests in these very long exposure situations.
Instructions:
Choose your film in the drop-down box. After framing your shot, note your camera's exposure time. Enter this value in the 'Metered Time' box. The approximate exposure time, taking reciprocity failure into account, is shown as the 'Exposure Time'. You can easily attain this exposure time by simply setting the 'Exposure Compensation' on your camera to the displayed value. You can also use the built-in timer. When using 'Sound Alarm', make sure your media volume is turned-up.
Using Filters:
If you meter your scene without the filter attached to your lens or light meter, select the appropriate light loss in the 'Filter Factor' dropdown. The app will automatically calculate the required exposure adjustment before applying the reciprocity failure curve. If you meter through the filter (which is standard for cameras with built-in Through-The-Lens/TTL metering), the light loss is already accounted for by your camera. In this case, leave the Filter Factor set to 'None' to prevent double-compensation.
Current Supported Films:
- Adox CHS 25/50/100
- Adox CHS 100 II
- Adox CMS 20 II
- Adox HR-50
- Adox Silvermax 100
- Agfa APX 100/400
- Bergger Pancro 400
- Fomapan 100
- Fomapan 200
- Fomapan 400
- Foma Ortho 400
- Fuji Acros 100
- Fuji Acros II 100
- Fuji Provia 100F
- Fuji Velvia 50
- Fuji Velvia 100
- Fuji Pro 160 NS
- Fuji Pro 400H
- Fuji Superia 200/400
- Harmon Phoenix II 200
- Ilford Delta 100
- Ilford Delta 400
- Ilford Delta 3200
- Ilford FP4 Plus 125
- Ilford HP5 Plus 400
- Ilford Ortho Plus 80
- Ilford PanF Plus 50
- Ilford SFX 200
- Ilford XP2 Super 400
- Kentmere Pan 100
- Kentmere Pan 200
- Kentmere Pan 400
- Kodak Ektar 100
- Kodak Portra 160/400
- Kodak TMAX 100
- Kodak TMAX 400
- Kodak Tri-X 320/400
- Rollei IR 400
- Rollei Ortho 25 Plus
- Rollei Retro 80S
- Rollei RPX 25
- Rollei RPX 100
- Rollei RPX 400
- Rollei Superpan 200
Contact & Support:
If you encounter any issues, have feature requests, or need further assistance regarding Exposure Assistant, please reach out via email: