PAD 113 - Infrared Sky

[Mike Farley]

Day 113 and this is the type of picture which I had in mind when venturing out to the local wood on day 111. On that occasion, I did not get the sky streaked with cloud as I had wanted, but the weather made up up for it a couple of days later. I used an infrared camera to lighten the trees and grass, and darken the empty parts of the sky above.

Leica M8
Summicron-M 28 f/2 (APS-H sensor, 36 mm equivalent for 35 mm full frame)
Hoya R72 infrared filter
1/45 sec
f/4
ISO 320

[Nina]

Using your IR modified camera was a good idea, it works really well here.

[Mike Farley]

Thanks, Nina. I have two cameras which I use for infrared, only one of which has been specially modified for the purpose. This picture was taken on the other one which has weak infrared filtration, allowing me to put an IR filter in front of the lens and shoot at handheld speeds without having to up the ISO too much.

[davidc]

Hmm there's something about this not hitting it for me, can't put my finger on it yet. Having a think and will post some comments.

Unless - given it's photo sharing - you'd rather I didn't

[Mike Farley]

Hmm there's something about this not hitting it for me, can't put my finger on it yet. Having a think and will post some comments.

Unless - given it's photo sharing - you'd rather I didn't

No problem, go ahead.

[Paul Heester]

Im impressed with your quick shutter speed. I always thought adding the Hoya filter adds many seconds to the exposure. I read (a while ago) that most Canon DSLRs are not that effective when using the R72 so havent re-visited the idea since. Anyone else using these filters?

[Mike Farley]

Im impressed with your quick shutter speed. I always thought adding the Hoya filter adds many seconds to the exposure. I read (a while ago) that most Canon DSLRs are not that effective when using the R72 so havent re-visited the idea since. Anyone else using these filters?

Paul, digital camera sensors are sensitive to IR light, but it interferes with colour rendition, AF and metering so most cameras have very effective filters to eliminate it. Putting a filter such as the Hoya R72 in front of the lens means that most of the light in the visible spectrum is blocked, so the two filters counteract each other and it this that leads to the long exposure times since very little light reaches the sensor. Since one of the reasons to use IR is to achieve the ghostly effect of foliage which becomes pale, if there is any wind whatsoever there is no possibility of getting a sharp image.

Some older cameras have weaker IR filtration, thus they can be used with an IR filter and the camera I used for this shot is amongst them. In fact it achieved a fair bit of notoriety when it was launched as colours, particularly those in clothing made from artifical fabric, were not rendered accurately. The manufacturer's solution was to supply UV/IR filters, at great expense to the customer, to remove the remaining IR light. How this was not discovered during testing before launch I know not, as paying customers discovered the problem within a couple of days of the camera becoming available. Suffice to say, the company has not made the same mistake since!

The happy upshot is that the camera works quite well for IR photography and it is just about possible to achieve handheld shutter speeds provided the aperture is not too small. Being a rangefinder, there is a separate viewfinder so the scene is not seen through the lens. Just as well, as once the IR filter is attached it is impossible to see through it. Also, being manual focus, it is straightforward to apply the focus correction which is required as IR has a longer wavelength than the visible spectrum and the rays do not focus in the same plane as visible light, so lens optics are not corrected for it. The final advantage is that cameras converted to IR have a filter permanently fitted which cannot be changed, making the camera useless for anything else, whereas I can use a different strength filter or revert to normal photography if I wish.

I did a presentation ("Taken As Red") at the club about infrared earlier this year and followed it up with a thread on the topic, which might be of interest.

viewtopic.php?f=2&t=243&hilit=infrared