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Re: Are lower magnification objectives brighter?

Posted by lechristophe on Mar 22, 2021; 5:21pm
URL: http://confocal-microscopy-list.275.s1.nabble.com/Are-lower-magnification-objectives-brighter-tp7592013p7592015.html

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Hi Andreas,

I've always understood this in relationship to a constant detector with a
given pixel size (like a camera): lower magnification spreads the same
signal over a smaller number of pixels, resulting in higher intensity for
the pixels that contain the signal. This is more tricky with point-scanning
microscopes.

Christophe

On Mon, 22 Mar 2021 at 18:02, Andreas Bruckbauer <
[hidden email]> wrote:

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>
> Dear all,
> Are lower magnification objectives brighter than higher magnification ones
> when they have the same NA, e.g. a 40x NA 1.4 objective compared to 63x NA
> 1.4? I mean for confocal microscopy.
>
> Confocal.nl stated this is a recent webinar and on their website:
> “A lower magnification allows for a larger field of view and brighter
> images, since light intensity is inversely proportional to the
> magnification squared”https://www.confocal.nl/#rcm2
>
> I would think that this is caused by less light going through the smaller
> back focal aperture when the illumination is held constant? Most of the
> light is clipped as explained in fig 1 of
> https://www.nature.com/articles/s41596-020-0313-9
> So, the microscope manufacturer could adjust the illumination beam path
> and laser powers to best suit the objective?Or are lower magnification
> objectives really brighter?
>
> The field of view will obviously be larger for the 40x objective, but I am
> more interested to understand the claimed benefit in brightness.
>
> best wishes
>
> Andreas
>