Wednesday, July 18, 2007

Guess which one has been shot using a quartz lens?

This is a test shot to compare a Fluorite/Quartz lens with a "normal" lens ("X135") for UV photography. The shots show one each per row. All done at f8 and using the new 2" Baader U-filter for the UV shots. The images are cropped/sized for about the same size for comparison. Focus was NOT completely identical, so don't use correct focus as as indicator for your guess, look out more for detail, sharpness & contrast.
[I used Nikon D70 + Baader 2" U-filter + X135 lens. UV shot about -10EV compared to VIS shot, identical postprocessing and resize for same appearance due to different focal length]

And your guess for the quartz lens is which one?

Here are two high resolution images if you click on them:







Some more specific shots with decent UV pattern may be seen here now, first the visible light shot:




and the UV shot:




Details (100% crop), first the visible light shot:




and the UV detail shot:



Oh, nearly forgot, the quartz lens is the first row in the first
two images, the second row is that older X135mm lens, I
calibrated for UV shooting. This was also used for all following
shots. The slight disadvantage is, that you focus in visible
light, flip the Baader U filter in front of the lens, make a
focus adjustment to the UV marker (like that red dot
indicating the IR mark) and shoot. Not such an effort if
you can save quite some bucks...

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

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

On Fluorescence Photography

Taking shots of flowers esp. close up I noticed that pollen seems to somewhat lighten up. So I made a test using a UV flash, but had a UV-blocking filter (Baader UV/IR Cut filter) in front of my taking macro lens. It gets quite obvious, that at least some flowers use the energy in UV light to enhance the brightness of their pollen to make it more visible to insects - their pollinators.

Here some macro shots I did using the 2" Baader-U for the UV shots and 2" Baader UV/IR Cut filter for UV-Fluorescence. The fluorescent pollen get clearly visible.

Some examples for that follow. Here the visual shot first:
(click on images to get larger (1024 pix) images)




The UV shot however looks very different and since the pollen looks quite dark, this means that the UV energy gets absorbed by the pollen. So where does it go to? It gets transformed (maybe just partly) into visual light.




So if we now use the UV cut filter for that African Daisy, this is made visible:




So this is another trick what flowers do to attract pollinators. Here an even closer macro shot of that:




Another example of a multitude of ideas nature has applied.

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>