[Theme] Pictorial UV

[Frank Fremerey]

This UV capture of the Venus Transit 2004 is a long-standing favourite. It conveys the sheer power intensity of the Sun. In fact, so intense the camera (D70) literally was set on fire. This is its last message to the world before I had to quickly remove it from the mirror lens it was attached to and quench the flames.

Hot memory. Stunning vision and I learned how much you value rare astronomical events.

[Frank Fremerey]

An Enchanted Orchard

The most coonvincing example so far. Is this  pure UV or is it an overlay with other parts of the spectrum?

[Frank Fremerey]

Here is another favourite, entitled "Hidden Menace"

Sometimes you are just lucky with what happens inside the frame during a 30 sec exposure:D

very cool translucent car event. Love it!

[Bjørn Rørslett]

The most coonvincing example so far. Is this  pure UV or is it an overlay with other parts of the spectrum?

UV as pure as the technology of that time allowed.

[Frank Fremerey]

UV as pure as the technology of that time allowed.

so 200nm to 400nm roughly?

[Bjørn Rørslett]

Given the camera and filter, more likely 330 to 390 nm.

[Frank Fremerey]

Such a small band? How very interesting. Thank you. And what can be done today?
Are the chips getting better in the short wavelenghts?

[Alaun]

UV as pure as the technology of that time allowed.

Bjørn, are that dandelions? They seem to have a "non dark" centre, could that be a bit of IR as well?

[Bjørn Rørslett]

Yes, they are dandelions, and the centre of the mops are dark. However, the processing and colour balance of such captures are quite different today.

Some IR leakage is likely. Could not be circumvented at the time.

[Bjørn Rørslett]

Such a small band? How very interesting. Thank you. And what can be done today?
Are the chips getting better in the short wavelenghts?

Most of the biological information of UV in fact is concentrated in the even narrower band 350-380(390) nm. Extremely small amounts of UV below 320 nm reach the Earth's surface, and for that we should be very grateful.

As to the sensors, it's a world of difference what big money for specialised gear can bring you, and what we 'laymen' in this context can get hold of. However, do realise what difficulties working much below the UV-A range would entail. One would be in a real danger of getting eye and skin damage of the most severe kind unless protective suits are donned. The UV-B and shorter UV range are for astronomical use mainly.

[Alaun]

Some "today gears" pictures, a dandelion, dandelion with primroses, and daisies, and the first one PSed

(gear: Oly F Zuiko 25/4 set to f11, Makario UV filter set and Panas. GH3 modified for UVIR, all a bit cropped)



 

[Frank Fremerey]

Another technical question: in the picture "a3_1030653" I see bokeh. How does the "light color" influence the way that the circles of confusion are rendered?

[Alaun]

easy physics: smaller wavelength ==> you can use higher f-numbers 

[Bjørn Rørslett]

Pure UV images tend to be sharper than their visible counterparts. Presuming of course the actual lens can deliver in UV.

Bokeh is influenced as well, but not in a simple manner.

[Bjørn Rørslett]

Back to the topic of pictorial use of UV.