Camera settings and lens focal length settings are the crucial points of taking an acceptable passport photo. follow guides are based on International Civil Aviation Organization (ICAO) standards. Hope that may help you to take acceptable passport photos.
Types of camera:
1.Digital Cameras set to an photo capture size of 8 megapixels or higher.
2.Instant film cameras.
3.35 mm film cameras
lens focal length settings
1. if you are using a fixed-focal-length lens, the best focal length of lens for passport photo taking would be between 90 to 130mm(35 mm equivalent focal length)
2.if you are using a zoom lens, for the best result, you should locked into a focal length between 90 to 130mm (35 mm equivalent focal length)
For example If you using a APS-C format camera, you should set your focal length between 144 to 208mm, more information about 35 mm equivalent focal length you may visit this website: http://en.wikipedia.org/wiki/35_mm_equivalent_focal_length
