Normal infrared photography would mean buying a filter (typically a Hoya R72), composing the image on a tripod, fitting the filter in front of the lens with correct filter size and taking a long exposure (~30 secs in sunlight). This still doesn’t yield a very good photo as the noise generated by the process is substantial.
I replace the filter in front of the sensor itself with one that allows radiation with wavelength greater than e.g 715nm (to ~1200nm) to pass through. This allows only (invisible to humans) infrared to pass through.
Digital imaging sensors in most cases are just as sensitive to infrared light as to visible light. Camera manufacturers stop infrared light from contaminating the images by placing a hot mirror filter in front of the sensor which blocks the infrared part of the spectrum while still allowing the visible light to pass.
I remove this hot mirror filter and replace it with a custom manufactured infrared or clear filter.
Autofocus is retained in both cases, and focusing through the viewfinder is still possible after the IR conversion due to the placement of the replacement mirror behind the view prism in the optical train. This makes focusing and scene adjustment easy, unlike trying to achieve this with a front lens fitted IR filter like the Hoya72.
The internal hot mirror filter blocks most of the infrared light from reaching the imaging sensor, thus making the exposure time much longer, usually seconds long and requiring a tripod. That long of an exposure makes it difficult to photograph and really slows you down as you have to set up a tripod for each shot.
Also because you place the opaque infrared filter in front of your lens you can't see to compose and focus, making it even more difficult and time consuming to take each shot.
After conversion the exposure times are much shorter, as an example a converted 350D on a sunny day on ISO 200 at f/8 would have a shutter speed of around 1/400th of a second. This makes handheld shots easy and since there is no filter in front of the lens you can focus and compose like normal.
I use Schott glass only. The filters are custom manufactured to exacting scientific specifications. Both filters are made of high quality optical glass offering excellent visible light transmission (clear glass) or infrared response (longpass infrared hot mirror).
The metering will work as usual. Keep in mind that the amount of infrared light varies from scene to scene even if overall brightness is the same. Since the camera light meter senses only visible light you may need to dial in some exposure compensation, example: +1.3 stops.
Each lens diffracts infrared light differently so some lenses may be a bit off in one direction or the other and with zoom lenses the focus may be different on each zoom setting and most different at the opposite ends of the range. In most cases you can stop the lens down to f/8 or higher and get good results.
I get as close to a dust free conversion as is practical but in most cases there will remain a few dust specks normally invisible in photographs except at high focal length (> f10 ) and against a very light background.
These can be removed manually using a graphics editing package or with later models, using Canon's dust delete data functionality if so desired.
I can also supply 665nm or 720nm IR converted Canon xxxD or xxD range of DSLRs of your choice - contact me for more detail.
These shots below where all taken handheld by myself with a 350D.
I'm by no means a pro but goes to
shows you what you can achieve with a bit of an eye and some experimentation.
665nm as the extra color information is useful in B&W
conversion and allows for better false color infrared.
With CS3 B&W conversion tool you can adjust each color slider in the B&W conversion. This is the same as having
a color filter on your lens and being able to adjust the intensity. Just shoot RAW.
1000 times easier than IR film days!
Autofocus adjusted for IR.
Due to the difference in Infrared wavelengths an adjustment to the autofocus point is made.
Whenever shooting IR stopping down a couple of stops will always lead to sharper focus with any lens.
This means that you should shoot in f/8 to f/11 range.
Attempting to shoot f/1.8 f/2.8 can lead to back focus. Where your are focus a couple of inches in front of your subject.
Some older lens have markings to show where the IR focus point is. Shoot at f/8 to f/11 and you won't have any problems.
Typical exposure in daylight will be ISO 200 f/8 1/100th sec to 1/1000th sec
No sensitivity lost in IR conversion!
Enhanced Color IR
Allows more color to pass and is especially suited for color IR work with great saturation and color range.
BW also looks quite good although with a bit less contrast without adjustments.
Enhanced Color IR Filter (665nm) Infrared conversion by LifePixel costs $450 = £272 = Euros 315 alone.
The IR filter alone would set you back $180 from Lifepixel in the US, excluding shipping cost to UK!
** Please take note.
This disclaimer is NOT unique to my service.
I can confirm similar suppliers of these services such as LifePixel and Baader,
as well as individual outfits such as Gary Honis, Hap Griffin all have similar disclaimers in place.