The CIE established the Standard Deviate Observer (SDO) CIE 1989 for fields of 10degrees enabling the evaluation of discrepancies caused by the variability among these observers. This observer could also be applied to smaller fields, depending on the physiological causes of this variability in color-matching functions (cmf's) among observers. Here, we have obtained a new Deviate Observer (which we call JF-DO) established from the cmf's for small fields (2degrees) corresponding to two groups of real observers: JAM, MM and CF; AY, JR, MR, JL, JA and FA. Both groups of cmf's were measured experimentally in our laboratories using one for each of the different experimental methods and devices. All the new cmf's of the 9 real observers were referred to a new, unique system of unreal primaries, which we call X'Y'Z' (derived in a way similar to that of the CIE 1931 XYZ system of unreal primaries). To establish a new JF-DO for small fields, we followed a procedure similar to the one used by the CIE to establish the CIE 1989 SDO. A comparative study was also made between the cmf's of the CIE 1989 SDO (established for fields of 10degrees), the SDO from Stiles-Burch (which we call Poza-SDO, developed for small fields), and our JF-DO. For this comparison, the cmf's of all these deviate observers were referred to the new system of unreal primaries X'Y'Z'. (C) 2003 Wiley Periodicals, Inc.