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SFX Part Three

This is the third time I have tried the SFX film with an R72 filter and thought this time I would get a 135 film and run it through my trusty Mamiya so that I can have 3 times the amount of pictures to try bracketing and see what works. I also used the film in Sri Lanka where bright sunshine is more or less a given.

To summarise for those who like the odd technical bits – this is not an IR film but has the IR sensitivity and when used with a Deep Red R72 Hoya filter and rated as 12 ASA (which is + 4) then you get a B/W image with IR aspects to it.

Previous attempts on bright sunny days have been completely hit and miss and so even though I asked questions on SFX Discussion boards on the net – no one was giving me the answer or at least the whole answer.

So, the next four images are the same apart from one aspect. Each one is one stop brighter than the last.

The first image is measured using 12 ISO for the 200 SFX film and all use the R72 filter.

So this gave me 1/500th at f8 on my digital meter and should give me the correct result in a picture.

So I then tried 1/250th and kept it at f8. Which is the same as dropping f8 to f4.

So, as I didn’t know the results I thought I would continue with the test – so this is f8 still and 1/125th.

And finally I tried to go slower at 1/60th and still f8 to give this;

So if you add the +4 in rating the film as 12 and then add +3 for the speed of the shot that was reduced from 500th to a 60th – you get roughly +7 and an image that is clearly more IR than B/W.

If you look at the bus in the car park, you will see a couple of figures that show that these are all the same time line – so, either people using SFX don’t want to tell new users the whole story – or there is something sinister afoot with my cameras…

Posted by simon on September 14, 2010

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