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Eric,

Keep in mind that the "eye" can be deceived, but you need to use a 
reference sample such as calibrated fluorescent beads and a camera or 
some other unbiased detector (PMTs on a confocal). Also, you must be 
certain that the magnification of the systems are identical as the 
brightness of the image is inverse with the magnification, actually 
the mag squared. The Zeiss could appear 10% dimmer which would be 
noticeable. It is actually more complicated than that.

You refer to using similar objectives but the Nikon and Zeiss 
microscopes have different internal designs and may have different 
light transfer efficiencies, and, of course, the objectives and the 
microscope bodies are not interchangeable.

When it comes to objectives regardless of platform, I always ask the 
vendor to provide three of the same objectives because there can be 
significant performance differences even within the same objective 
type. I also measure the 3-D point spread functions to be certain 
that the specification are met.

Regarding the 10x objectives, are you sure that you were using lenses 
with the same NA. A 0.45 Zeiss should be a little brighter than a 0.4 
NA Nikon. With the 60x lenses, another factor is that you are 
comparing oil lenses that depend critically on having the right oil 
and the correct coverslip thickness, not much of an issue for low 
mag. air objectives but very important for the former.

Let's just say that you can't go by impressions. You have to measure 
and insist that the vendor provide proof that their systems 
objectives, etc., meet specifications. Sometimes they are 
significantly better.

Mario



>Search the CONFOCAL archive at
>http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
>
>Hello all
>Please forgive me if these kind of issues are not discussed here.
>While testing for new microscopes I had the strong impression that high
>mag optics are much more luminous and crisp with Nikon than with Zeiss
>(ex: Nikon 60x/1.4 versus Zeiss 63x/1,4 plan apo).
>I had the exact oposite impression using their plan apo 10x/0,45
>
>Of course this is very subjective and I'd like to know if some of you
>are aware of more objective differences (i.e. in the making of these
>objectives) that would sustain/negate my impressions.
>Best Regards to all and congratulations for keeping this list so active
>Eric
>
>
>Eric Scarfone, PhD, CNRS,
>Center for Hearing and communication Research
>Department of Clinical Neuroscience
>Karolinska Institutet
>
>Postal Address:
>CFH, M1:02
>Karolinska Hospital,
>SE-171 76 Stockholm, Sweden
>
>Work:  +46 (0)8-517 70343,
>Fax:   +46 (0)8-301876
>
>
>http://www.ki.se/cfh/


-- 
________________________________________________________________________________
Mario M. Moronne, Ph.D.
ph (510) 528-2400
Fax (510) 528-8076
cell (510) 367-8497

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