Lomo lamp & green filter

[Galf]

This Lomo 6V 20W lamp and mount fits nicely on a Wild M5 stereo microscope.
You always see these lamps with green filters attached, why is that? This one seems to be fitted with an original bulb and the result with the green filter is an even more yellowish light than without it. If I hold a blue filter in front, the effect is as to be expected a more neutral white light. Why green then? It puzzles me...

IMG_20240404_215230~2.jpg (52.95 KiB) Viewed 1059 times

IMG_20240404_215017~2.jpg (64.68 KiB) Viewed 1059 times

It is an oldie but she's still in fantastic shape!

[charlie g]

Green wavelengths in our light spectrum, the wavelengths human eyes are most sensitive to ( our retinas if 'normal retinas').

I think this a reason green filters are often found with vintage ( ?tungsten bulbs, halogen bulbs illuminators?).

My circa 1980 Nikon-Labophot-Pol came with a 'yellow-goldish heat filter', the ever popular blue filter, and yes...a green glass filter.

BTW, my Zeiss junior stand has a near identical illuminator as this Lomo illuminator you share with us.

I sense a lot of these varieties of glass colored filters are to deal with days of film recorded microscopy and the variety of'color temperatures of illuminator outputs...just my sense of the green filters.

charlie g

[Galf]

Thanks Charlie,

Now I remember the old B&W 35mm film days and the use of filters for accentuating certain 'colors' or aspects. Long ago for me... It seems my ToupCam automatically compensates for the yellowish/greenish hue.
Still, I haven't found a compatible blue filter for this illuminator yet. Personally I think I don't like this filter for normal use, i.e. plain watching.

[BramHuntingNematodes]

There is also a reasonably flat portion of the focal length/ frequency function of the humble achromat lens around the green wavelength. Predominantly green light can make black and white photos of subjects through aachromat lenses very sharp.