[bscott]

Is it possible to use an m lens on m setting, set the aperture and shutter speed and have the ISO setting adjust as the light meter changes? For example, set the f stop to 8 the shutter speed to 250 and have the iso adjust as the light meter changes.

[filoxophy]

In Pentax cameras, that would be TAv mode. Most models have that as a position on the main mode dial.

Edit: Whoops, missed the M lens part of the question. No, you cannot do TAv with an M lens. Pentax DSLRs have no way of knowing what aperture the M lens is set to...a complaint that has been registered by many, but Ricoh recently confirmed in an interview that no changes are coming.

[fgaudet]

No, only mode available with K and M lenses are M and Av.

Your best bet is M and set your aperture, hit green button to meter, adjust ISO, hit green button, until you're happy with the shutter speed.

In any auto metering mode, the camera has two things to adjust *(Except Tav)* (aperture/iso when in Tv, shutter/iso when in Av, aperture/shutter when in Sv) With an M or K lens, the only settings the camera can change are ISO and shutter (Av mode) And M mode, well is manual

[bscott]

No, only mode available with K and M lenses are M and Av.

Your best bet is M and set your aperture, hit green button to meter, adjust ISO, hit green button, until you're happy with the shutter speed.

In any auto metering mode, the camera has two things to adjust *(Except Tav)* (aperture/iso when in Tv, shutter/iso when in Av, aperture/shutter when in Sv) With an M or K lens, the only settings the camera can change are ISO and shutter (Av mode) And M mode, well is manual

Thanks so much to both of you for the quick reply. I now understand better how it works and will use my lens in the correct settings.