There has been a LOT of talk recently over the type of conversion service you choose for your dedicated IR camera system! Personally, I have used them all. I have had everything from a 590nm Goldie to an 850nm Deep IR conversion and recently, 2 Full Spectrum conversions. All are good (some more than others)!
If you are going to convert a DSLR camera then you should look into a specific wavelength conversion. The reason is that with a mirror/prism based DSLR you actually look through the lens. This means that if you choose a FULL SPECTRUM conversion, you would be attempting to look through the IR filter (which is screwed into the end of the lens you are currently using) which will make focus/composition all but impossible. If you hold up a IR filter, 665nm and up they are almost impossible to see anything through! The drawing of a DSLR optical path to the left shows the light path and problem.
OK, lets digress a little….
A Full Spectrum conversion is one in which the anti-alias and IR blocking filters (hot mirror) are removed from in front of the sensor and replaced with a clear piece of glass. This type of conversion will let you program your camera’s Infrared wavelength with the addition (in front of the lens) of an Infrared filter to ANY wavelength you desire, including UV, Normal Color & IR! Nice! But…. with a DSLR you
have to look through the lens and IR filter to focus and compose….. So not a good choice. BUT, if you are using a P&S like the Canon G9, 10 or 11, or the new Mirror-less DSLR like the Olympus PEN family with interchangeable lenses then this would be the way to go. There is even a factory converted full spectrum camera out there from Fuji, called the Fuji IS-1. It was designed for police CSI departments and comes with a full range of IR/UV filters to modify how it shoots! You can still find them on Ebay.
Now, a specific conversion involves the removal of the internal filters as described above but then replacing them with an IR filter of some sort (popular choices are 665nm and 720nm, but there are many more!). Since you now do not have to look through an IR filter in the optical path you can use a normal DSLR!
I am currently using BOTH systems. I have a 590nm Goldie converted Canon 20D (DSLR) an Olympus PEN E-PL1 mirror-less DSLR at Full Spectrum and an Olympus PEN E-P1 at 720nm. The E-PL1 PEN is my favorite camera for IR (I have had about 10 different IR cameras so far!). I like the Full conversion due to the fact that I can change its flavor at any time simply by changing the external filter on what ever lens I am currently using! This opens up a whole world of possibilities when I am out in the field shooting.
Keep these 2 types of conversions in mind when you are deciding which camera to convert as well as what wave length to use!