Table 2.

CryoCLEM correlation precision using FluoSpheres as correlation markers.

Data sets	CryoEM nominal mag.	Fiducial based correlation
		No. of fiducials	Precision σC [nm]
Sample 1	9300	9	32.5
	5600	10	45.5
Sample 2	9300	5	12.2
	5600	4	30.3

Measurements were performed on four data sets acquired on a plunge-frozen EM-grid with only FluoSpheres and TetraSpeck microspheres (sample 1). Sample 2 additionally contained plunge-frozen cells infected with Ad5-488 viruses. 4 to 10 FluoSpheres of 100 nm were picked manually on each image and used as fiducials for coordinate transformations. The correlation precision σ^C is calculated as described by Kukulski et al. [23] (see Section 2).