The Coastal Optics 60mm F4 Apo Macro lens is a truly amazing optical engineering feat. It is apochromatic from ultraviolet, visible light, through to infrared. This means that the light from all three spectral range will be focused at the same point, so the image remains nice and sharply focused; bear in mind it is supposed to let through a significant amount of the UV, unlike other apochromatic lenses.
It is the only such lens I know of which is still in production with such an apochromatic capability – even the UV Nikkor 105mm F4.5 has no focus shift for UV and visible light (but not infrared). The Coastal Optics is also said to be very sharp from wide open. But it does have its weakness (the hotspot issue), although that can be overcome through various ways – I will talk about this later
The coatings on this lens is different to those optimised only for the ultraviolet range (which all look very similar). It is large, heavy/well-built, focusing is firm so you are unlikely to accidentally adjust the focus on it.
Here are its specifications:
Focal length: 60mm
Aperture range: F4 to 45
Construction: 10 elements in 9 groups
Transmission waveband: 290-1500nm
Apochromatic waveband: 315-1100nm
Maximum magnification: 1 : 1.5
Lens mount: Nikon F-mount
Filter: 52mm thread
Current price: US$5750