This is actualy very poor cluster, dominated by 6.8-mag quadriple star STF 446 (mags: 6.86, 9.9, 10.3 and 12.0). Remaining stars are dimm, 12- to 14-mag, and are situated mainly NW from STF 446, less than 2' away.
Although the cluster (i.e its brightest star) might be, under very dark skies, detected with the naked eye, you will need at least 120 mm telescope and power above 100x to even begin to detect remaining stars in the cluster. With good seing, 8" telescope will show up to 20 stars.
It is a 5' diameter cluster with cca 30 stars, having magnitudes between 11 and 18. In very good conditions, cluster propably can be detected with 4" telescope, and 8" telescope will resolve about 15 stars. You will need a 12" or 13" telescope and averted vision to see all 30 stars in the cluster.
This is very rich area of Milky Way, so many other clusters are within 2° range. Brightest of them is NGC 129.
Berkeley 58 is an open cluster in the NW part of Cassiopeia, close to the border of Cepheus, in very rich area of Milky Way. It is the first in 2°-long line of clusters extening further to the NW, and including NGC 7790, NGC 7788, Frolov 1, Harvard 21, and King 12.
It is a 8' diameter cluster with cca 30 stars, having magnitudes between 13 and 14. The cluster can be seen in 3" refractor as a faint nebulous patch. You will need 8" telescope and power above 80x to detect individual stars. In 14" to 16" telescopes, at 150x, Berk 58 is dense cluster of 20 mostly faint stars. Averted vision should help resolve many fainter stars....
It is a small cluster, with its brightest part having less then 5' in diameter. Four most brightest star shines at magnitudes between 9.2 and 11. Those 4 stars form the shape of kite. Total number of stars in the entire cluster (having 15' in diameter) is somewhere around 90. Except the 4 main stars, all other are dimmer than m=11.7. The cluster is unique for having a well-defined zone of low star density in a 3' diameter region, immediately surrounding the nucleus, inside the "diamond", propably due to dark interstellar matter obscuring this region.
You will need at least 4" telescope and power of 25x to see some more stars.
Using telescopes bigger than 10" might show up to 30 or 35 stars.