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I've measured it quantitatively and the performance difference flips surprisingly close to the coverslip (see supplemental info, Fisher & Kuo 2009 PNAS 106, 133-138). For an Olympus 60x U-PlanApoS lenses, comparing 1.2 and 1.4 NA, the flip happens ~8 microns into an aqueous sample. For fluorescence closer than ~8um, oil is brighter, whereas for objects further, water immersion is brighter. If lenses aren't matched, then the cross-over can happen elsewhere, but the relative shapes of the curves are the same. Oil lenses (1.4NA) will have half the brightness by ~50um.
For the information you've provided (higher NA on water lens), I'd expect the cross-over to be closer to the coverslip surface.
-- Scot
============================================================================
...............Scot C. Kuo (410) 955-4536; email:skuo@jhu.edu...............
...Director, Microscope Facility, JHU-SOM, www.hopkinsmedicine.org/micfac...
..Assoc Professor, Biomedical Engineering & Cell Biology, www.jhu.edu/cmml..
----- Original Message -----
From: Gabriel Lapointe <[log in to unmask]>
Date: Thursday, October 4, 2012 9:16 am
Subject: [CONFOCALMICROSCOPY] Oil vs water objectives
To: [log in to unmask]
> *****
> To join, leave or search the confocal microscopy listserv, go to:
>
> *****
>
> Hi,
>
> I have a user who insist that using a 1,27NA water immersion
> objective is
> brighter and would give better images than using a 1,4NA oil
> immersion. I
> understand that deeper into the media that would be true. But, in that
> particular case, we are talking about imaging GFP at less than 100 micron
> away with a spinning disk.
>
> So, I was wondering at which distance from the coverslips do we start
> seeing benefits of using a water immersion objective over an oil objective
> in aqueous media.
>
> Thanks for your help.
>
> Sincerely
> *Gabriel Lapointe, M.Sc.*
> Lab Manager / Microscopy Specialist
> Concordia University, Biology Department
> 7141 Sherbrooke St. West SP 534
> Montréal QC H4B 1R6 Canada
> [log in to unmask]
> cmac.concordia.ca
>
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