Thursday, August 23, 2018

UV-Nikkor 105mm vs Coastal Optical systems 105mm lens for reflected ultraviolet (UV) photography II

I got another Coastal Optics (now JENOPTIK CoastalOpt®) f4.5 / 105mm lens, so today about shooting with two dedicated UV lenses, the Coastal Optical Systems / Jenoptik UV-Micro-Apo f4.5 / 105mm and the classic UV lens, the UV-Nikkor f4.5 / 105mm in a truely non-scientific photographic comparision at shooting in reflected UV, using the Baader-U filter at sunlight. Both lenses were used fully open at f4.5.

[click on image to see a larger one]

Chimney about 10m away:


Chimney about 20m away:






The UV-Nikkor 105mm image is shown on the left side, the Coastal Optical Systems 105mm on the right side. White balance was done for the UV-Nikkor 105mm.

The UV-Nikkor 105mm seems to have (quite) an edge over the Coastal Optics 105mm in terms of sharpness and contrast, when used fully open at f4.5. That difference will get smaller stopped down, and the Coastal will gain sharpness and also contrast, as my previous test has shown.

Both lenses require about the same white balance, due to their flat UV transmission and show about identical exposure, with exposure times having a slight nod towards the Coastal Optics lens (1/3 stop less), which in practice is rather insignificant. See the following transmission spectra I have measured, which shows that the modern broad range UV-VIS BBAR coating the Coastal Optics lens has offers some higher transmission on average which actually calculates as 1/3 stop difference:

PS: But there is a rather unexpected feature the Coastal Optics lens has (identical with both lenses I have): Its Coastal made Nikon-F mount is 0.3mm wider than the original Nikon-F mount which leads to a rather wobbly fit. To cure that, I bent the camera adapter springs a bit wider to achieve the needed tight fit.

I have written about that Coastal Optics lens HERE
Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site