Standard Hot Mirror Filter

[smyth]

I've googled this filter I have, but the definition seems kind of vague as to what it is and when it should be used.

I got it for free, as it was stacked on top of a UV filter, which was on a lens I got. I unstacked to reduce IQ degrading, but my main question is:

What are they used for?
When do you use one?
Does anybody use one?

Thanks

 

[Big Mike]

Never heard of it :scratch:

 

[Dweller]

I had never heard of it either, but a quick google tells me it is used to "eliminate IR pollution". A problem I never knew I had. :er:

Hot Mirror Filters Press Release - Tiffen.Com

 

[smyth]

I had never heard of it either, but a quick google tells me it is used to "eliminate IR pollution". A problem I never knew I had. :er:

Hot Mirror Filters Press Release - Tiffen.Com

That's funny, because that press release is dated 2008, and I'm sure this filter is at least 5 years old.

I tried the filter a couple of times too, and I can't see any noticeable difference between one with it and one without it.

Alex

 

[sofa0ne]

I know I am coming to this conversation a long time after it started but I had to add a little information that others here might find helpful.
(So forgive me for bumping it, and yes this is my first post so hopefully I don't anger anyone here for doing so.)

After discovering a Tiffen Hot Filter in a box of camera gear that was given to me, I too was wondering just what it was used for.
I had heard that most digital camera's produced these days comes with an Hot Mirror / Infrared filter over the sensor so why would this be needed.
Having read the Tiffen Description that was on the packaging and searching the web I came across this site and little other information so I decided I would test it out and see if I noticed a difference. I started with testing it for what it was designed filtering out IR that could potentially wreck a shot.
For my tests I set up a Canon T3i with a 18-55mm Kit Lens, I chose this camera simply because the filter size I had matched and for no other particular reason. Though lens and camera choice will most certainly play into the variables.
I set it to live view and began shooting video without the filter, and then pointing a TV remote(while pressing buttons) at the camera it would pick up the IR beam flashing. This was an obvious sign that IR was making it's way past the built-in hot mirror(IR filter). I am sure if one wasn't present at all it would be even more evident.
So now to test the filter, I do the same thing as before with the filter attached it, and certainly reduced the amount of IR that was making into the camera. Some IR still made it's way in but not nearly as much.
So this filter does really filter out IR and does so quite nicely.


So why would one use such a filter?
Well if your camera's sensor didn't have an IR filter(due to manufacture or modification) or if it had a very weak IR filter you would now have a solution to your problems.
I know I have been considering modifying an older camera to shoot IR but was concerned that I would be creating a camera that would have only one sole purpose so this filter could potentially solve that problem. I plan on shooting with it some more to compare if it effects colors and such both JPG and RAW and will report back when I have that information as well as test shots to share if anyone cares to see them.