Differences in light loss between the different filter options on a converted camera
Besides the difference in aesthetics between our infrared filters, there is also a different amount of light reaching the sensor depending on how much is blocked, and it can result in the need to dial in an EV compensation.
Differences are explained in stops (each stop is a doubling or halving of light)
Normal photographs: 0 stops – the baseline
720 Infrared: ~0 stops compared to normal exposure
550 Infrared: ~1-1/2 stop Gain compared to normal exposure
590 Infrared: ~1-1/3 stop Gain compared to normal exposure
665 Infrared: ~2/3 stop Gain compared to normal exposure
850 Infrared: ~1-3 Stop Loss compared to normal exposure
Full Spectrum: ~2 Stop Gain compared to normal exposure
The 720nm filter works out to having about as much IR light available as a normal camera has visible light, the easiest to expose for. Other IR filters have more or less light available.
The compensation highly depends on the specific lighting conditions used, and how much IR and visible light there is available. They can also be somewhat lens defendant, with some lenses not transmitting as much IR as visible light (particularly in the 850 range).
This light sensitivity is the same whether this filter is installed as a dedicated infrared conversion, or it is used as a lens filter over a full spectrum conversion.
Light loss when using an infrared filter on a regular camera
When using a normal camera, the only options for infrared photography are the 720 and 850 filters. The 590 and 665 let in some visible light, so when used on a stock camera you will only pick up the visible portion of that filter, not the IR portion. The 720 filter can have a 10 stop or more light loss, and will often require long exposures and a tripod. The 850 filter is even darker, and can be a 15 or more stop difference.
