Focusing a Full Spectrum Camera

If you’ve read any of my other blogs, you might know that I started IR photography as a spinoff of my astrophotography. Both of these types of photography have some similarities. First, most cameras need to be modified to shoot IR photos. For the exact same reason, you’ll need to modify your camera to shoot nebula-type astrophotography. This is needed because the internal UV/IR cut filter blocks the both the IR light for IR photography and the H-alpha light for shooting nebula (See my astrophotography series for more details).

When I first got started with astrophotography, I modified a canon 300D (Digital Rebel) with a full spectrum modification. I figured it would be the most flexible. Six years later, I still feel that way. I like the full spectrum modification as I can shoot astro, or any flavor of IR.  by adding an original white balance filter allows me to use the camera for regular color photography.

The biggest drawback of a full spectrum modified camera is the need for external filters. These block the light that would normally pass through the viewfinder. Lifepixel calibrates their IR modified cameras for autofocus. But when shooting IR with a full spectrum mod, you loose the use of the viewfinder.

When shooting the 300D, I would compose, focus and prepare the shot with the filter removed. I’d then screw on the filter and set the lens to the higher f/numbers and shoot. It was sort a crap shoot whether or not I’d get what I wanted. It did work and I shot many photos like this. One of my all-time favorites was shot with the 300D, using this technique.

I was enjoying shooting IR and wanted a better way to compose and focus my images. So my second modified camera was a Canon 40D, also modified for full spectrum. It was one of the first DSLR’s that had a live-view option. I found that this was the key to effectively using a full spectrum camera. Since the camera is modified, it sees right through the externally mounted IR filter. So live-view works quite normally. I used this camera for several years before upgrading to a slightly higher resolution Canon 50D. This camera also had a better live-view LCD, which made focusing much easier. Then I finally bought and modified a full frame Canon 5D Mk II. All my cameras were modified with a full spectrum modification.

When you shoot IR with live-view, you can see the scene just as the camera sees it. After all, it’s the main sensor shooting this live-view image. I found that shooting with a green white balance gives the images in the live-view window a more appealing color.  It is much easier to compose and focus. Having a custom white balance also makes the post-processing easier.

This is typical of what you’ll see on the camera’s LCD if you shoot without a CWB.

This is the same shot with a Green CWB frame and the camera set to use this frame for CWB.

The biggest problem for me was being able to see the LCD screen, while shooting in the bright daylight hours. I tried shading the camera with a black cloth draped over the camera. But this was pretty tedious and uncomfortable.  So I bought a Hoodman loupe and never looked back. This allows you to see the LCD very clearly. On many cameras you can also zoom live view, which will further improve your focusing with the loupe.

Keep in mind that using the LCD for composing and focusing will consume more power than viewfinder methods. So be sure to carry an extra battery or two. Alternatively, if you use a battery grip you’ll have longer sessions before a battery change is needed.  This comes at the expense of portability.

The camera & loupe can be a handful to manage if you’re doing hand-held shots.  So I resolved myself long ago to shooting with a tripod. I made a custom tripod which is a little more compact and works perfectly for my IR set-up.  But nearly any tripod will work, as long as it is stable.

Focusing an IR modified camera can be a challenge. So I thought it might be worth reviewing this topic again. With a little kit and a little practice, focusing becomes an after thought allowing you to concentrate on the other aspects of getting a great image. You don’t have to have a full spectrum modified camera to use this technique. But you should use this technique if you have a full spectrum modified camera. Practice, have fun and happy shooting.