Exposure Meter

[Hansraj Vyas]

My Gossen Super Pilot exposure meter gives one stop difference between incident and reflected light readings. Is something wrong with the meter ?
Hansraj.

 

[Donald Miller]

Not necessarily since you are metering two different things. Reflective readings will give you the average of the reflective luminance over the average of those that are within the viewing angle of the meter. Incident readings give you the average of the luminance impacting the translucent dome. Typically this would be the average equating to an 18% gray card for incident (five stop average)...the reflective meter may be greater or lesser than that value.

 

[bdial]

A one stop difference is pretty much normal between an incident reading and a random reflective reading. If you do a reflective reading from a grey card it should be very close to the incident reading (that is, closer than 1 stop).

 

[Roger Hicks]

A one stop difference is pretty much normal between an incident reading and a random reflective reading. If you do a reflective reading from a grey card it should be very close to the incident reading (that is, closer than 1 stop).

In fact, a reflected light reading from an 18 per cent grey card SHOULD differ about 1/2 stop from an incident reading because a reflected-light reading of an 'average' scene should be based on 12-13 per cent reflectivity, not a Munsell mid-tone (18 per cent).

There's a bit more on this sort of thing in the Photo School at www.rogerandfrances.com in the free modules on ISO speed and subject brightness ranges.

Cheers,

R.

 

[Hansraj Vyas]

Thanks for all the replies. I have taken incident reading by pointing meter dome towards the Sun and reflective reading from 18 per cent grey card-facing it towards the Sun and reading the shadowless card from about 4" distance.