We present gri CCD photometry of 44 Abell clusters and 4 cluster candidates .
Twenty one clusters in our sample have spectroscopic redshifts .
Fitting a relation between mean g , r and i magnitudes , and redshift for this subsample , we have calculated photometric redshifts for the remainder with an estimated accuracy of \sim 0.03 .
The resulting redshift range for the sample is 0.03 < z < 0.38 .
Color-magnitude diagrams are presented for the complete sample and used to study evolution of the galaxy population in the cluster environment .
Our observations show a strong Butcher-Oemler effect ( Butcher & Oemler 1978 , 1984 ) , with an increase in the fraction of blue galaxies ( f _ { B } ) with redshift that seems more consistent with the steeper relation estimated by Rakos and Schombert ( 1995 ) than with the original one by Butcher & Oemler ( 1984 ) .
However , in the redshift range between \sim 0.08 and 0.2 , where most of our clusters lie , there is a wide range of f _ { B } values , consistent with no redshift evolution of the cluster galaxy population .
A large range of f _ { B } values is also seen between \sim 0.2 and 0.3 , when Smail at al .
( 1998 ) x-ray clusters are added to our sample .
The discrepancies between samples underscore the need for an unbiased sample to understand how much of the Butcher-Oemler effect is due to evolution , and how much to selection effects .
We also tested the idea proposed by Garilli et al .
( 1996 ) that there is a population of unusually red galaxies which could be associated either with the field or clusters , but we find that these objects are all near the limiting magnitude of the images ( 20.5 < r < 22 ) and have colors that are consistent with those expected for stars or field galaxies at z \sim 0.7 .