Can you still use your modded DSLR for daytime photography? Yes, as long as you have a UV/IR blocker somewhere, either directly over the sensor or as a pop-in or infront of the lens. Can you make the colour balance perfect? Of course not! Did you think the camera manufacturers would needlessly cut back the sensitivity of their cameras by using those spectral-shaping filters on the sensors? But I think that the above shows how close you do get to a "satisfactory" white balance. All the above are analogues of shooting with Custom White Balance. All were captured Raw and converted in Canon Digital Photo Professional, setting White by clicking on the table next to the elephant's toes. The 1Ds (top-left) image is as close to "reality" as modern cameras can go. What we do know in advance is that we will most likely have problems with deep reds and anything that reflects IR profusely; live foliage and also some dyes and paints. The highly IR-reflective dyes and paints are, frankly, unpredictable. But if you cut out most of the IR by using a UV/IR Blocker then the IR becomes much less of an issue and you are left with only deep reds as inaccurate. To humans, deep reds, like H-alpha, appear as dark reds. Note the dark red flowers arrowed above. Note how much lighter these flowers come out on the modded 20D and the modded 40D, despite the use of rectangular-passband UV/IR Blockers. Other colours are quite satisfactory IMHO. The IDAS LPS-P2 does introduce some tints, but it still produces something "acceptable" if the image is looked at in isolation. The upper rightmost image demonstrates that it is impossible to have acceptable white balance in a modded DSLR with no UV/IR Blocker at all. The lower rightmost image demonstrates the non-predictability of IR-reflectors. Note how that blue on the elephant simply disappears and how bright all the live foliage and flowers come out. Click on "original" below right to examine the individual colours. A real-world daytime example follows on the next slide.