Dichroic/Microscope Florescence Filters

SmoothOperator wrote:

D Cox wrote:

Matty W wrote:

I've never tried it, but I did attempt to buy those color blind glasses (that are apparently just band pass filters) to see if they would make my landscapes more vivid.

Didymium filters have more effect on human vision than they do on most cameras. They filter out the yellow, near to the Sodium wavelength, and the narrow-band filters used in typical Bayer mosaics already have a gap there.

I think dichroic filters are different than didymium, dichroic filters work by thin film reflection, like soap bubbles. They use them to tune very specific color bands, so that light that stimulates fluorescent dyes is filtered out. It looks like a single color like red or green is most popular, but there are also multiband filters for using three four or five dyes, which is what I am more interested in. Interestingly enough they come in complement pairs, one to ensure the excitation light is not in the same range as the emission light, and the complement for imaging.

They are indeed.

My experience with didymium filters is that they work quite effectively on my cameras. Their transmission spectra shows multiple sharp absorbance bands, the absorption being due to the elements in the glass. They are great for reducing sky glow from old low pressure sodium street lights, but are much less effective with the more modern high pressure sodium lighting. They should also be good for photographing glass blowers...

Dichroic filters use interference effects to adjust the transmitted wavelengths, they typically only have one transmission band in the visible range, but usually with significant overtone bands in the NIR. They have a sort of mirrored look.

I've done some very brief experiments with (blue, green , yellow & cyan) dichroic filters with my full spectrum camera & haven't found a use for them.