0.55$) and MS $0440.5+0204$ ($z = 0.19$). These clusters were discovered in the Einstein Medium Sensitivity Survey(EMSS)(Gioia et al. 1990), and were covered by a SCUBA mapping observation by Chapman et al.(2002a) and Smail et al.(1998; 2002a).

In the next section, we describe our data collection, including our observations. In section 3, we address the result of our imaging surveys and the various features of the candidates of the SCUBA source counterparts. A discussion is given in section 4. In this paper we use the cosmological parameters $H_{0} =$60.0 km s$^{-1}$ Mpc$^{-1}$, $\Omega_M = 0.3$, and $\Omega_{\Lambda} = 0.7$. All magnitudes without any notice are given in Vega magnitude. We used the values in Fukugita et al. (1996) for converting between the AB and Vega scale magnitudes.

Observation, Data, and Data Reduction
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Optical Data
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### HST data

Deep optical imaging data for both clusters taken by WFPC2 through a F702W filter were retrieved from the HST archive system at STScI. The total exposure times for each cluster were 10400 seconds for MS $0451.6-0305$ (Program ID 5987) and 22200 seconds for MS $0440.5+0204$ (Program ID 5402), respectively. We used a post-calibrated data and combined them into one image by 