The focus lens is an add-on for the SFA light heads to produce a higher illumination intensity!
This is a simple adapter that slips over the front of your existing NIGHTSEA SFA light head and grips with a friction fit. It is available with two options for the focal distance: 30mm or 50mm.
No lens – illumination spot approximately 15mm diameter with the light head positioned 50mm from the surface.
50mm lens – central spot approximately 5mm diameter, intensity increase ~2x.
30mm lens – central spot approximately 2mm diameter, intensity increase ~3.5x.
The images below show the focus lens add-on and the effect. The three illumination spot images were made in manual exposure mode and are indicative of the relative intensity.
No Focus Lens
50mm Focus Lens
30mm Focus Lens
Considerations for lens choice:
To gain the benefit of the 30mm lens it is necessary to position the light head very close to the subject. This may be challenging in the tight space beneath a microscope objective. It might be more suited for photoactivation, where a high light intensity dose in a small area is often needed.
The 50mm lens provides a trade-off – brighter fluorescence, easier to work with.
Note – If the light head has a snoot installed that will have to be removed to use the focus add-on.