It might be worth saying a few words about colours recorded by film. Kodak's old Elitechrome EB100 and newer E100SW are my basic films; both push processed to 400ASA. To stop aurora movement Fuji's Provia 400 is used (push processed to 1600ASA). All these films record beautifully reds and greens in aurora while Kodak's films also record nicely blue tints.
There is, however, a problem: now-a-days those favourite Kodak films are discontinued! Luckily (?) auroral activity fell drasticly in late 2005 and I had had a good supply of my favourites to photograph all before that drop in activity.
But the question is: is it also what is perceived visually? In general: films greatly exaggerate reds compared to how they appear visually. And film blues I have never perceived as blues but rather perhaps a bit as white-bluish tints. When scanning pictures, it is a routine in PhotoShop 1) to use levels to spread scan to full range of output bits and to brighten dim aurora; 2) to adjust saturation of master or selected colours; 3) finally to check if there is anything to gain by adjusting brightness and contrast. There are few cases when I have reduced (instead of increasing) saturation and when film response and visual perception have matched (see "Year 2000" spring and "Year 2001" July-Oct and Nov-Dec auroras). Thus honestly speaking auroras are usually more colourful on film and in digital form (although on these www-pages they are somewhat supressed compared to how they appear in my PhotoShop). However, outdoors when actually watching aurora, it is immediately evident that there is no means to show the immense vastness of this heavenly lightshow. And this implicates that in spite of all manipulation of pictures, nothing comes even close to what one can see in nature.
I have tried Canon's PowerShot G2 digital camera for auroras (and also seen pictures taken with some other digital cameras). It appears that they all exaggerate yellows to the degree that greens turn out uncomfortably caramel; they are even further away from truth than what films record. With reduced yellow saturation results are wonderful and at least G2 is capable to record extremely faint auroras with no disturbing noise (settings compare to 400ASA film, f=2, 15 sec exposure with no reciprocity).
|Aurora root 2000||Aurora root 2002|