Originally Posted by kiwirider
I don't know anything about NDVI
I have done quite a lot of work with IR and CMOS sensors though. The filter quoted would be a good starter - it is good quality Schott glass. I think I would want to be going a bit higher though - say 720nm ....
Do you need visible red for NDVI?
We have a wide verity of expertise in this group! Whatever you can tell us about this sensor may be helpful to those who don't know a lot about cameras (aka - me). As far as NDVI, you do need a visible band as a basis of comparison. NDVI compares whats being reflected to whats being absorbed, which can tell us a lot about the health of the plant. If its not absorbing or reflecting as it should be, this can mean that the plant is either sick or damaged. Most often NIR and VIS-R are compared.
If you are going to go with a strictly IR filter for vegetation analysis I wouldn't go any higher than what kiwirider said (720nm). I have found it often better to go with a filter that captures as much of the NIR as possible to help identify the plants absorption signature. Every plant reacts slightly different to VIS and NIR radiation, some absorb more and some less. Some more in the 800nm area some more in the 950nm. So much so that it creates a kind of "fingerprint" for each plant type. So if you were interested in doing something like this and you purchased a 950nm filter, you would cutting out a large amount of the data available to you. This of course is bound by the limitations of the equipment and software.
That is just my findings though! If you find otherwise please feel free to say so, an open discussion on the topic is always helpful to all
Ok so rereading the filter it says that it BLOCKS everything till 650 (VIS-R is 620–750nm) and it allows 90% of light from 730 - 2000nm. So what does it do with the light from 650 - 730nm? Ideally if you are doing NDVI's you'd want to take the image without a filter to capture as much of the NIR and VIS as possible. However if you were just doing NIR imaging and didnt want to do NDVI's I think either of those filters would work fine.