Filter Adjustment

Dear Experts

Iºm a user of JEOL 2200 FS with omega filter. I would appreciate someone tells me to do EELS in TEM Mode ( at high magnification), should we correct stigmatism of Filter everytime? Using alpha 3, spots 1 or 2 with ENTA aperture 4, to get better resolution, in SPECTROSCOPY mode the spot is always with a shadow ( long tail) unless I make the beam fully deconverged as I loose my signal even in ZLS. Does anyone has an idea on the reason of it? In alpha 1 it is even worse.

best

Ali, from Portugal