We report new metallicity determinations for 39 red giants in a 220 square arcminute region , 1 \fdg 8 southwest of the bar of the Large Magellanic Cloud .
These abundance measurements are based on spectroscopy of the Ca II infrared triplet .
We have carefully considered the effects of abundance ratios , the physics of Ca II line formation , the variation of red clump magnitude , and the contamination by foreground stars in our abundance analyses .
The metallicity distribution function ( MDF ) shows a strong peak at [ Fe/H ] = - 0.57 \pm 0.04 ; a tail to abundances at least as low as [ Fe/H ] \approx - 1.6 brings the average abundance down to [ Fe/H ] = - 0.64 \pm 0.02 .
Half the red giants in our field fall within the range - 0.83 \leq [ Fe/H ] \leq - 0.41 .
The MDF appears to be truncated at [ Fe/H ] \approx - 0.25 ; the exact value of the maximum abundance is subject to \sim 0.1 dex uncertainty in the calibration of the Ca II IR triplet for young , metal-rich stars .
We find a striking contrast in the shape of the MDF below [ Fe/H ] \leq - 1 between our inner disk field and the distant outer field studied by Olszewski ( 1993 ) : red giants deficient by more than a factor of ten in heavy elements relative to the Sun are extremely scarce in the inner disk of the LMC .
Our field star sample does not reproduce the full MDF of the LMC star clusters , but seems similar to that of the intermediate-age ( 1–3 Gyr ) clusters .
We have also obtained abundance estimates using Strömgren photometry for \approx 10 ^ { 3 } red giants in the same field .
Photometry is the only practical way to measure abundances for the large numbers of stars necessary to lift age-metallicity degeneracy from our high-precision color-magnitude diagrams .
The Strömgren measurements , which are sensitive to a combination of cyanogen and iron lines , correlate well with the Ca II measurements , but a metallicity-dependent offset is found .
The offset may be due either to variations in the elemental abundance ratios due to galactic chemical evolution , or to a metal-dependent mixing mechanism in RGB stars .
An empirical relation between photometric and spectroscopic abundance estimates is derived .
This will allow photometric abundance measurements to be placed on a consistent metallicity scale with spectroscopic metallicities , for very large numbers of stars .