I’ve been doing a lot of experimenting over the past 9 months or so with different photography projects. Everything from using new software plug-ins to technical experiments, like using a ridiculously strong close-up filter. And I’ve just done another one.
If you want to take infrared photographs, you have two basic paths to take:
1. You can buy an IR filter which passes only infrared light, screw it on the end of your lens, and put the assembly on a tripod. Why? Because most digital cameras have “hot mirrors”, or a filter over the sensor which blocks most of the IR light. This means it takes a long time to get enough IR rays to make a decent exposure. The stronger the hot mirror, the longer your exposure. Filters cost from $20 – nearly $200 depending on brand and size.
2. You can send your camera to a company who removes the hot mirror and calibrates your auto-focus for infrared. IR wave lengths are different from visible light and actually focus sharply at different distances. This procedure costs from $250 – $350, from what I’ve seen.
I don’t have an extra $300 lying around, so I’ve been going about it the first and cheaper way. I’ve been using a Canon Powershot G3 since it was a new model in 2002 (see this post https://ebgriffith.wordpress.com/2013/02/25/infrared-photography/), and its relatively weak hot mirror still requires a tripod. This means I’ve only been able to shoot static subjects, and have to setup a tripod and compose for every shot. By the way, I did say “cheaper”, but I just found that the B+W brand 093 filter I bought 12 years ago for $75 is now about $150 on Amazon.com. That’s more expensive than some multi-element lenses!
I still have my old EOS 10D, so I ordered a step-up ring to make my old 58mm filter fit my 28mm prime lens (which has a 52mm filter size). The Canon 28mm f/2.8 is not an expensive lens, but it is quite sharp. I purchased it as an alternative to my softer Sigma zoom (back before I got my red-striped Canon L lenses). Since my 58mm IR filter won’t fit on my 17-40mm 4.0L with its 77mm filter size, I had to use the widest smaller lens I had. Enough text! Let’s see my first attempt in my own backyard!
Shooting in the shade with weak winter sun still got a decent result with the shutter open for a full half minute. The procedure is focus manually before putting on the filter, then stop down to f/8 or smaller to avoid focus differences between IR and visible light. I could have gotten a shorter exposure using higher ISO setting, but I didn’t really need one.
This shot was obviously in full sunlight, but with the exact same exposure value as the shade shot. I kept shooting at different shutter speeds until I got a decent “mountain” in the middle of my histogram, instead of lopsided to the left. 30 seconds happens to be the longest shutter speed you can set in manual exposure mode on most EOS dSLRs. To go longer, you need to use bulb mode. I just got a timer/remote release, so that will be a future experiment.
These photo’s have been edited considerably. They look rather low contrast and gray straight out of the camera. Thanks to RAW files, I was able to sharpen and adjust them without loosing much image quality.
Just for comparison, my Canon G3 takes around one second to make an exposure with the same IR filter attached. I’d say that means the EOS 10D has a much stricter, stronger hot mirror in front of the sensor. I expect my much newer EOS 7D simply isn’t practical at all for IR photography.
So how would things change if I forked over $300 to have my old EOS 10D converted to be dedicated to IR photography?
1. I could take hand-held IR photos without a tripod with normal shutter speeds.
2. I could compose through the viewfinder because the IR filter is on the sensor, not the end of the lens. (You can’t see through an IR filter – it looks painted black.)
3. I don’t know for sure, but I believe the RAW files would be more contrasty and have a more pronounced IR effect without the IR-blocking hot mirror in the way.
I don’t know… those are some pretty tempting advantages! I should probably start saving my pennies!