Can the same results be achieved with standard infrared (IR) photography, or does an IRR camera make a significant difference? To address this question, we compare an InGaAs camera—used for Infrared Reflectography (IRR)—with a digital camera modified for infrared photography (IR). While an InGaAs camera is the preferred tool for imaging underdrawings, its advantages, although real, are often limited to specific cases.

It is commonly stated that pigments become significantly more transparent at longer infrared wavelengths, such as those captured by InGaAs cameras. This is true for certain historical pigments, but not universally; in many instances, the increase in transparency is modest or even negligible.

A modified digital camera can typically record radiation up to about 1000–1100 nm, whereas an InGaAs camera extends this range to approximately 1700 nm. However, beyond cost considerations, a key limitation of InGaAs systems is their relatively low spatial resolution. Entry-level detectors often have resolutions around 320 × 256 pixels, producing images that are only a fraction of the size of those captured with high-resolution digital cameras such as the Nikon D850 (8256 × 5504 pixels). Consequently, achieving comparable image detail requires time-consuming mosaicking of numerous IRR frames.

With these limitations in mind, it is important to evaluate the actual benefits of extended infrared imaging in terms of pigment transparency and the visibility of underlying features.