The full spectrum camera conversion
A full spectrum camera conversion is a modification where the camera’s internal IR cut filter is removed and replaced with a clear filter, making the camera sensitive to UV, visible, and IR light. At this point, the camera is useful for astrophotography and low light applications where having as much sensitivity as possible is helpful. On it’s own, it is also useful for some B+W photography and can lower the noise in the shadows. In general though, for regular photography and infrared photography, the results are not very appealing – on it’s own at least.
Why convert a camera to full spectrum?
The big benefit of full spectrum is that it allows you to put external filters on the lens to narrow the sensitivity to a certain range. Putting an IR filter on the lens will still allow for handheld infrared photography, just like a converted camera. Alternatively, using a hotmirror filter you can use the camera to take normal pictures. Putting a UV bandpass filter lets you take ultraviolet pictures (provided you use a good UV lens). Filters are available here. This is the most flexible conversion you can get, giving you 7+ options in one camera. Most importantly, it lets you still shoot normal color photography by using our hot mirror filter, meaning that you only have to carry one camera with you.
Best cameras for a full spectrum conversion
Full spectrum has some problems specific to a DSLR. Because most infrared filters are opaque, you will not be able to compose with the viewfinder with the filter on the lens. The autofocus and exposure systems also rely on visible light, making them inaccurate when the filter is on the lens. While exposures will be short, the obstructed viewfinder still makes shooting challenging.
To get the most out of a full spectrum conversion, it is good to choose a camera with live view. With live view, you can compose and shoot regularly even with the IR filter on the lens. With that combination, it is possible to use a filter for normal photography, the best filters for color IR photography, another filter for B&W IR, and even filters for UV photography. DSLRs with live view, and mirrorless cameras are very good for the full spectrum conversion because of this added flexibility. Some point and shoots have threaded lenses that will accept filters, others have adapters available, either in the form of an adapter tube or a stick on thread adapter, such as the one Lensmate makes. It is also possible to glue a filter adapter onto the lenses of most compact cameras to let them accept external filters.
One of the drawbacks of this system is that it relies on external filters for IR photography. If you have multiple lenses, it can get expensive to have filters in multiple sizes. Some lenses simply don’t offer the ability to mount a filter. With fixed lens cameras this isn’t an issue though.
While this flexibility is nice, it isn’t always necessary. While the ability to swap between IR filters is useful, it is possible to use different external IR filters with an IR converted camera anyway. With any IR filter, it is possible to mount a higher cutoff filter and use the camera like it only has that higher cutoff filter. For example, with a 665nm conversion you could use a 720nm, or 850nm filter and still take handheld pictures that will look exactly like the higher cutoff filter. You couldn’t use any lower filter though, like the 590nm filter. Because of this flexibility between the IR filters, it is also possible to choose the lowest filter you are interested in shooting with, knowing that you can always add on the higher cutoff filter if you change your mind.
Some people have even converted their primary camera to full spectrum, giving them one camera that can be used for all of their regular and IR photography. Most people, though, leave their best camera alone, and convert a second smaller or older camera for dedicated IR use. If that is your case, then you probably wouldn’t be taking many regular pictures with your IR camera, and wouldn’t need the complete flexibility of the full spectrum option anyway.
Two spectrum conversion
The two spectrum conversion makes your camera sensitive to visible and IR light only, and blocks UV light. This gives the same results for IR as with a full spectrum conversion, but provides better color rendition for visible light by blocking out UV light. When paired with our hot mirror filter, the sensor receives almost perfectly the same wavelengths as a stock camera for the best results.
A note about DSLR Live View
While many DSLRs have live view, not all of them are “true” live view. Some of the earlier cameras with live view would use a second sensor in the viewfinder to generate a live view. These sensors still work with visible light only and don’t offer any advantage for infrared compared to normal live view. The only time live view helps is when it uses the primary sensor. Sony and Olympus DSLRs tend to use a second sensor.
Choosing a Filter, DSLR and Compacts Color Performance, Choosing a Camera, CDHK