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Dear Benedikt,
I used a custom-built (not the Leica-Product) resonant scanner and a 
spinning-disc confocal with a fast CCD camera for calcium imaging in 
dendrites and spines of patched neurons in acute brain slices. Although 
we never systematically quantified signal to noise ratio vs. 
phototoxicity, from my own experience it seems that the spinning disc 
confocal is better when it comes to photodamage. The reason is that 
resonant scanners have a very short pixel dwell time, which you have to 
compensate for by illumination intensity, whereas the spinning disc 
uses a parallel scan which permits for longer exposures repeated 
several times during one illumination frame. Wang et al., Journal of 
Microscopy, 2005 is a very nice study where the difference between 
parallel scanning and single-point scanning is thoroughly analysed.
When dealing with large fluorescent volumes, spinning disc confocals 
have the problem of crosstalk between adjacent channels, but this 
dependes on the type of preparation you use. A disadvantage of the 
spinning disc is that it only has one pinhole size which limits the 
objectives you can use. Maybe you should also look into the visitec 
infinity 3 scanner if you want parallel scanning with different pinhole 
sizes.
Best,
Friedrich


Dr. Friedrich W. Johenning
NWFZ -Campus Mitte / AG Schmitz
Charite der Universitätsmedizin Berlin
Charitéplatz 1
10117 Berlin
Tel.: 030 450 528077
Mobil: 0173 2144701
Fax: 030 450 539943