Blue Moon over Castle in reflected ultraviolet (UV) photography

Today is a 2nd full moon within the same month, a "Blue Moon", which I have previously shot in reflected ultraviolet photography using my "work horse" UV filter, the Baader-U filter, and then superimposed to a normal night light shot of our castle here. Lens was my CERCO 94mm quartz flourite lens. All shots were done at about f5.6.

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Indeed, the moon has UV reflectance and it can be recorded using proper equipment which makes that nicely visible.

I have written about photographing the Moon previously HERE
 
Stay tuned, more will follow on that fascinating subject...

Nikon UV-Nikkor f4.5 105mm vs CERCO f4.3 94mm

As I was testing a Nikon UV-Nikkor f4.5 105mm, I thought it would be interesting to compare it to my CERCO f4.3 94mm workhorse lens, especially about possible chromatic aberration, sharpness and contrast. Target was a metallic precision ruler, light was sunlight. Only visible light photograhy was done here.

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CERCO top, Nikon bottom. Increasing f-stop setting towards the right, starting fully open leftmost.




Both lenses do not show CA. But interesting to note, how much higher the contrast of the UV Nikkor is. The CERCO shows futher decreasing contrast when stopping down (to the right) although flare control was used by using a deep hood against stray light. Both lenses are very sharp, but overall the Nikkor seems to be the clear winner here and it also covers FF sensors, which the CERCO does not do. Both are excellent lenses in terms of sharpness, but contrast and flare always need special attention, especially when using the CERCO multispectral lens.

I have compared quartz fluorite lenses in terms of their transmissions HERE

Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos

150mm Micro reproduction lens for reflected UV photography

Today about a recent find for UV photography, a high resolution (approx. 150-200 lpm) 150mm micro documentation lens, which I have tested positively for UV use. Of course it shows quite some restrictions, but I'm happy about finding such lens in such longer focal length (150mm), which allows for better working distance in some circumstances. All shots were done it studio. Lens for comparision was my CERCO 94mm quartz fluorite lens. Light source was a Xenon flash. All shots were done at about f8.

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Test images using Baader-U filter for reflected UV photography and as a target a Rudbeckia fulgida flower. Adjusted for comparison to even out focal length differences. Individual white balance set per image.

Cerco 94mm (left), Micro Documentation lens (right)

The micro docu lens does quite well and seems to be quite a sharp lens, even when used for UV.

Now about the spectral transmission:

It gets obvious that this micro docu lens only transmits down to about 350nm, but has sufficient transmission around 360nm to make flower UV patterns visible.

So to summarize I would call that a nice find, which adds to the repertoire of suitable UV lenses, especially since it has very high resolution also in UV.


Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos

EADS SODERN CERCO f4.1 94mm vs Coastal Optical Systems Inc. 105mm f/4 UV-Micro-Apo lens for reflected ultraviolet photography

Today about two specialized UV lenses, the EADS SODERN CERCO type 2085 f4.1 94mm and the Coastal Optical Systems Inc. (COSI) 105mm f/4 UV-Micro-Apo apochromatic quartz fluorite lenses. In lack of a flower with UV pattern, I'm using a African violet hybride flower for that test as well as my "work horse" UV filter, the Baader-U filter. Light source was Xenon light. All shots were done at f5.6.

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Diptych image CERCO 94mm (left) vs COSI 105mm lens (right), Visual light:
 

Diptych image CERCO 94mm (left) vs COSI 105mm lens (right), reflected UV using Baader-U filter (approx. 320-395nm, peak approx. 350nm):
 

Diptych detail image CERCO 94mm (left) vs COSI 105mm lens (right), reflected UV using Baader-U filter (approx. 320-395nm, peak approx. 350nm):
 

The comparison images clearly show that both lenses work exceptionally well for reflected UV as for visual photography and deliver sharp images rich in contrast and detail. I had to adjust the camera position to equalize the focal length differences, so this is not a scientific lens test, but the view of a user. Both come in Nikon-F mount, but the COSI lens covers full format sensors, the CERCO only about the smaller APS-C format (25mm image diameter).

P.S.: The images were not re-adjusted in focus between UV and VIS shots, to show that there is no focus shift between VIS and UV.

P.P.S.: those images accidentially work as 3D crosseye stereo images...

Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos

[UV] Old Achromatic vs modern Cerco Quartz Fluorite Lens for Ultraviolet Photography

Well, you may remember that I have shown here results using an older quartz fluorite lens from a spectrometer system. Here that now tested against my Cerco 94mm lens using a Gazania rigens flower that I have shown here a few times before. The Cerco images ("in dubio pro reo") have been adjusted in size a bit, to compensate for the different focal lengths (94mm vs about 82mm).

Here the results and I leave it to you to determine which shot was done using which lens; it is easy anyway as I will show also 1:1 crops.

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Visual shot:


UV using Baader-U filter:


Visual shot (detail):


UV using Baader-U filter (detail):


[the UV focus is not exactly identical for that last shot, so I'm not sure if that was caused by focus shift or most likely by a slight movement when I changed filters ... oh well]

Not that bad for such a relatively cheap part...

Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos