Stealth3kpl Posted August 22, 2016 Share #1 Posted August 22, 2016 Advertisement (gone after registration) I've noticed that my Portra shots go a bit blue in the high mountains and I don't like it! What filter should I be thinking of in such high altitude places? A simple B+W 010 UV+Haze filter or something better? Pete 1 Quote Link to post Share on other sites More sharing options...
Advertisement Posted August 22, 2016 Posted August 22, 2016 Hi Stealth3kpl, Take a look here Himalaya And Filters. I'm sure you'll find what you were looking for!
Les_Sismore Posted August 23, 2016 Share #2 Posted August 23, 2016 The overall blue colour cast arises because Portra (like all daylight colour film) is optimised for a colour temperature of 5 500K. At higher altitudes,on extremely bright sunny days and, surprisingly, on foggy days, the colour temperature can be much higher - up to 10 000K or more, and hence intensely blue. A colour correction filter is needed to bring the effective colour temperature of a scene back down to the temperature the film is designed for. A UV filter isn't enough - in the absence of any measurement, for altitudes up to 2 000 metres or thereabouts I would generally use a KR1.5 or 81B filter (medium rose / salmon pink colour), but for those near-perfect cloudless deep blue skies or higher altitudes, I would use a deeper rose coloured KR3 or 81C (or even 81D). These filters all have exposure factors greater than one, so be sure to include these effects in your exposure calculation. Also, remember to remove any filter if you are indoors, or you will literally be seeing the world through "rose coloured glasses". Some filter manufacturers have a lot of really useful information on the characteristics of their filters on the web, others are less informative. An additional benefit of using these filters is that they will cut back some of the scattered blue light that otherwise illuminates the shadows, so you should see the shadows in your pictures become darker. Similarly, colours that are weakened by blue will become more intense, and the scene will become more vibrant overall. Also, I always use a Skylight filter (very light salmon pink) on my lenses on those few occasions when I use Portra for general use (I prefer Ektar for landscapes - Portra for indoors and portraits). I have put some pictures (mostly Fuji films) in the Australian Landscapes thread in the Landscapes section of this forum. For some of these I used a KR1.5 filter - others were with a UV filter (ultra-pale straw colour). The difference in the overall colour cast of the pictures makes it easy to distinguish which filter was used in each case. I hope this helps, Cheers, L 4 Quote Link to post Share on other sites More sharing options...
Stealth3kpl Posted August 23, 2016 Author Share #3 Posted August 23, 2016 (edited) Thanks for this Les, just what I needed. Pete Edited August 23, 2016 by Stealth3kpl 2 Quote Link to post Share on other sites More sharing options...
gberger Posted August 24, 2016 Share #4 Posted August 24, 2016 Another vote for the 81C in high altitudes 2 Quote Link to post Share on other sites More sharing options...
LorenzoLandini Posted August 26, 2016 Share #5 Posted August 26, 2016 Pete, I second the above comments on the filters needed to correct the blue cast. Additionally, at a low temperature exposure times have to be increased because film behaves differently when it's very cold. Otherwise the images will be underexposed by 1/2 stop and have an even more visible blue cast. It's like the reciprocity factor for long exposure, same concept. Ansel Adams makes a reference to it in its books (who was shooting negative B&W) and I experienced it with the Provia, so I'd guess that somehow this is common with probably any film. I never been in Himalaya or else where at those altitudes and when I am shooting on the mountains I use E6 film (the Provia 100F) which may behave differently. A few years ago I did experience it shooting from the top of a skyscraper in NYC in January at -25c (pretty high altitude but not that high like Himalaya ) and back then I didn't know it and I ended up with slightly underexposed images and the blue cast. I did some research and found out the above compensation to be factored in. Cheers, Lorenzo 2 Quote Link to post Share on other sites More sharing options...
chris_livsey Posted August 26, 2016 Share #6 Posted August 26, 2016 http://www.kodak.com/global/en/professional/support/techPubs/c9/c9.pdf KODAK TECHNICAL DATA / REFERENCE C-9 Photography Under Arctic Conditions Cold temperatures may reduce the effective film speed and alter the color balance of color films. & lots more. Don't underestimate the increase in static risk either. 2 Quote Link to post Share on other sites More sharing options...
Chuck Albertson Posted August 26, 2016 Share #7 Posted August 26, 2016 Advertisement (gone after registration) Back when I was doing that sort of thing (stomping around at altitude and shooting Kodachrome), a 1A skylight filter soaked up the excess UV light pretty well. 2 Quote Link to post Share on other sites More sharing options...
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