OK, I am trying to do a blog a week to start with, once I get in the habit I might do more. The last blog was a set of images from our trip to France in May, these were shot with the Df and were intended to precede the short review of the Df. However, we are back in France, the sale on the house in Sheffield is just about sorted (fingers crossed) and as soon as that happens we will be here full time, until then half of my kit is here and half in the UK. In fact, wherever I am the kit I want is in the other place. When I went to review and publish the Df blog it wasn’t on the travelling hard disk, I had updated all the directories except, somehow, the writing directory.
So, an interim blog, I have always been interested in alternative light, Hazel and I converted a D100 by swapping the filter on the sensor for one that blocks all visible and UV light allowing only IR light to reach the sensor. DSLR sensors are sensitive from the near UV to IR and are limited to visible light by a filter that sits in front of the sensor. It is possible (though scary) to remove that and replace it with a filter with a different pass band, the new filter cost around £30. The D100 was my second DSLR, my first was a D70 that I no longer had, one of my D100s was swapped for my Fuji X-E2 as there was a £100 bonus on part exchange but I still had the one that I bought with the money I got selling my OM film kit. I wanted to keep that camera as it was in a direct line with the camera I bought with money that my Grandmother left me.
It is possible to take IR photographs by adding a filter to the lens, because the built-in filter allows some IR through, by filtering out visible and UV light and using a long exposure an image is obtained. The advantage of replacing the internal filter is that the camera behaves like a normal camera and exposure times are normal. With many lenses the focal plane is slightly different to that for visible light so shooting wide open is difficult unless the lens has an IR focus mark such as the R on the focus scale of this Sigma 15-30mm lens or a small red dot near the normal focus mark (if you are wondering why the Sigma is so battered, this was my everyday lens for several years on my D200, D300 and D600).
When the image is filtered for IR the colours are strange, vegetation is a very pale pink because it reflects IR light well. The sky is a dark red and the whole image has a red cast. However, using the Channel Mixer layer adjustment in Photoshop it is possible to swap the red and blue layers giving the commonly seen IR false colours.
Blanzay has several large Cedar trees that stand on and around the village green, this image, taken on a bright summer day, is of one of those trees as seen from our house.
In a future blog UV-induced visible fluorescence (UVIVF) which is my next experiment, for this you convert a flash gun not a camera and shoot in darkness. The UV light causes the target to fluoresce in visible light.
WEB LINKS of items mentioned:
Ebay seller of conversion filters https://goo.gl/qUuT69
Post by Danny
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