What do you do when you see blistering hot skies?

You shoot infrared, of course! (This was with my Canon Powershot A520, circular polarizer, red filter, linear polarizer using this method.)

I turned it so that enough light would come in to expose the reds, to balance out infrared rays which appear purple. This was 0.5 seconds.

Slow-shutter stuff! 0.6 seconds.

0.5 seconds.

1/3rd of a second.

Anyway, the 52mm Hoya R72 infrared-pass filter had been adequate for my Canon Powershot A520. However, when fitted to the Sony A100, it was a different story – the exposure times were now in seconds, and it was predominantly red. What I did not realize then, was that the red is actually the little red that the R72 lets through!

The Hoya RM90 infrared-pass filter is a true infrared-pass filter; it blocks all natural light, letting only infrared through.

The Hoya R72 infrared-pass filter lets very little red in instead. However, on older point-and-shoot digicams the infrared-block filter was weaker, so in long exposures more of the infrared purple appears than the red.

The circular polarizer, combined with the linear polarizer, and turned so that it was darkest, was mostly black… but let in some violet!

The smarter of you might realize what I figured. 🙂

That’s right, combine the Hoya R72 filter with the two polarizers to kill off all natural light! The R72 took care of everything except red, while the two polarizers removed everything but violet (which is on the other end of the color spectrum from red.)

Note that the filters are screwed in reverse, because I did not have a 55-52mm step-down ring to fit the 52mm filters on my Sony 18-70mm F3.5-5.6 kit lens. 🙁 I used two UV filters, 55mm and 52mm, superglued to each other, instead.

The orange tape is there to show alignment; when the two tape markers are aligned, the polarizers do not let any light through (except a bit of violet.)

I then made my maiden voyage to Digicolor, Jalan Ipoh, where I discovered they had the same thing – a China-made, brandless infrared-pass filter! The price? RM55 for a 77mm true infrared-pass filter!

The 77mm Hoya RM90 infrared-pass filter would’ve been RM600 from some sources.

They also have 77mm warming circular polarizers for RM55 too! If I got any lens with anything larger than 55mm I’d get a set of 77mm filters. 😀

And so, I got Grace one, plus a 58-77mm step up ring for her Canon 18-55mm F3.5-5.6 kit lens. I got to take it for a test run. 🙂

Oh, and they have loads of step up and step down rings, all on a huge rack! Mount reverser rings (to put a lens front first on a SLR body) and reverser rings (to make two lenses face each other, to do super macro, albeit without superglue) all for under RM30! China-made madness!

From left to right, top to bottom: Sony A100 at 50mm F3.5 1/2s ISO1600 using Hoya RM90 equivalent; Sony A100 at 50mm F3.5 1/10s ISO1600 using Hoya R72; Sony A100 at 50mm F1.4 1/4000s ISO1600 using Hoya RM90 equivalent; Sony A100 at 50mm F11 1/320s ISO100 no filter; Sony A100 at 18mm F3.5 30s ISO400 using Hoya RM90 equivalent; Sony A100 at 18mm F9 1/80s ISO100 no filter; Canon Powershot A520 at 35mm equivalent F2.6 1s ISO200 using Hoya RM90 equivalent; Canon Powershot A520 at 35mm equivalent F2.6 1s ISO200 using Hoya R72.

Canon Powershot A520 at F2.6 1/10s ISO200 using Hoya R72.

The Hoya R72 is still very usable, especially on the Canon Powershot A520, where it can separate areas by the infrared intensity; purple for infrared and red for others.

Sony A100 at 50mm F4 1s ISO1600 using Hoya R72 and two polarizers.

I can get a similiar effect using the R72 and two polarizers on the Sony A100, if I dial in the right amount on the polarizers. Note the slight red tint in the skies!

So what about my infrared-modded Fujifilm Digital Q1?

35mm equivalent (this was taken with the webcam manual focus lens, before I put SLR lenses on the Q1) F3.5 1/2000s ISO100 using Hoya R72.

Same exposure, without filters this time. The blue gets to leak into the picture! In most cases the Q1 captures mostly infrared unless it is in a flourescent-lit room.