By Scott Quier
There are any number of companies that will modify a digital camera such that it's sensitivity to visible light is greatly reduced and its sensitivity to near Infra-Red light greatly enhanced. Based on my experiences with a friend's modified camera, I elected to go with MaxMax
Why and how to go IR?
- I was and am well pleased with the sharpness of the images I captured using the camera I borrowed from a friend.
- There are other doing the same work, Life Pixel and Khromagery. This second vendor is doing business in Australia.
- Ah, the pricing. Life Pixel and MaxMax were approximately the same price ~$450USD. For those in Australia, Khromagery offers the service on Canon DSLRs for AUS$380.
MaxMax offers two different IR pass filters for their conversions, a 715nm and an 830nm. I selected the 830nm conversion based on this statement on the MaxMax website:
The advantage of a 830nm filter is that the red, green and blue channels are more evenly exposed than at 715nm. ... When you more evenly expose the RGB channels, the camera can resolve better. Also, the infrared effect is more dramatic at 830nm versus 715nm - skies are darker and clouds whiter.
What this means could be a surprise to some - it was to me! (Don't get me wrong, I love the result, but it was a surprise.)
Here we see a screen shot of Adobe Camera Raw histogram for a sample image before and after the application of a custom white balance.
The histogram above is for this set of images. The one on the left is a straight JPG conversion of the Canon RAW file, no other processing applied. The other image is with a custom white balance (CWB) applied.
Applying the CWB couldn't be easier. Just click anywhere in the image with the ACR White Balance Tool. The results you get will be nearly identical, regardless of what area you select for sampling.
This is a representative histogram of an image captured using a MaxMax 715nm modified Canon XTi. Note that the response curves for the three color channels are not nearly as uniform as that of the 830nm modified camera. This, then, allows for the swapping of the Red and Blue channels to have an effect on the image.
On the left, the image straight out of the camera. On the right, the image after swapping the Red and Blue channels using the Channel Mixer.
Some things I have learned:
- What you see and what your sensor sees can be (and usually are) two different things. For example, I was shooting towards the end of the day in what I thought was quite low light and adjusted exposure accordingly. This resulted in a 2-stop over-exposure.
- Just like the MaxMax pages indicates, the 830nm conversion incurs a 2-stop impact on exposure as compared to shooting with visible light. This varies some with your subject and the time of day (see first point). Green plants and clouds reflect more IR than you think they might, dirt and portions of the sky a lot less. Bracket your exposure and/or do a lot of chimping.
Lessons Learned (cont.)
- I found shooting manual was the easiest way to get a satisfactory exposure. My process is to:
- Set the aperture/shutter speed/ISO combination such that the camera indicates about 1 2/3 "over-exposed".
- Take the shot.
- Check the histogram to find that the exposure is somewhere between good and 1 stop under-exposed.
- Adjust your exposure settings to compensate.
- Shoot again.
- Repeat as necessary.
- If you want any chance at achieving false colors in your IR photograph, the 830nm conversion is not the way to go.
Lessons Learned (cont)
- Canon (and I think most other manufacturers) place a number of filters before the camera sensor in the light path. One of these is the anti-aliasing (AA) filter. The AA filter is used to actually blur the image a bit. Why? To reduce moiré patterns in photographs. If you look closely at this photo, you can see some of this effect in the vertical components of the bridge railing.
- Removing the AA filter can result in some incredibly sharp photographs - Post Processing sharpening is something that you will need to be extra careful about.
These are some daffodils, just as they are starting to bloom, presenting beautiful, bright green leafs/stems and brilliant yellow flowers. As you can see, greens and yellows are very bright when viewing reflected near-IR light.
Impressions of the service:
- Once I had made my decision, I contacted MaxMax via e-mail to ask if they calibrate the camera during the conversion. I got clear, concise, and complete response the next day.
- In the ordering process, I was informed that I would be receiving a UPS tracking number for the return shipment. I never received that information.
- I sent another e-mail to MaxMax once USP tracking indicated that the camera had been delivered to them. I was looking for confirmation from them that they did, indeed, have the camera. They responded the same day.
- Time for the entire conversion (from drop off at UPS until it was delivered) was just over a week. That's pretty good.
You can discuss this review in this thread here on Digital Grin!