So I've purchased a new lens, but the trouble I'm having is picking out an infrared filter. I know I need a 77mm thread size, but I'm seeing prices bounce from $20 to $200, and I"m not sure what "R72" and "RM72" and "950nm"... I have no idea what I'm looking for!
I used to use a R72 filters on my lenses. you don't have to spend a mint, any good piece of glass is good for this purpose. I believe my filters were Hoya.
regards, tom
Before you buy a filter, what camera are you using?
Not all DSLR's will give good results with an IR filter.
I have a 77mm filter that worked well on my D70 before I got it converted, but it doesn't do well on my D300.
If you've already used IR filters on your camera and have gotten good results, please disregard this post.
from personal experience I've found that the cheaper IR filters don't tend to have a steep wavelength cutoff so that visible light at the top of the red channel is still transmitted by '720nm' filters for example.
I use a modified Canon 60D with a 665nm IR blocking filter replacing all of the internal sensor filters that does have a steep cutoff, I chose this filter because I wanted the top end of the red channel to still come through so I can use a false colour technique in post processing.
A good 720nm, like a Hoya one, will block almost all visible light but does let a small amount through giving you the option to play with channel mixing etc. The longer wavelength IR filters like 820 or 900+ nm only allow IR light through and will need long exposures to get any response from the camera sensor if the original sensor filters are in place, and the higher the value the higher the black and white contrast is achieved.
re ND filters, the cheaper filters tend to produce a slight colour cast which can cause problems, again Hoya or Lee filters are colour neutral.
Bjorn has a comprehensive list of (Nikon) lens data - - with ratings of how they'll fare with a particular camera model in IR. Note his list is not current.
You can click on the mm range and examine all within that category:
