triangular said:
I really like the images I've seen from the Hoya R72. Is this the same as the RM72?
Sometimes people get the Hoya number wrong (and they almost never put the dash in the number). There is no RM-72, it's just an R-72. Hoya "RM" filters RM-90 and RM-100 are not "sharp cutoff", which is OK, because they're way up at 900nm and 1000nm, so the soft cutoff (letting through light below 900nm or 1000nm) isn't a severe problem. If there was an actual RM-72, it would pass so much visible red below 720nm that the visible red would totally dominate the picture. Like the mess you get if you try to shoot through a B+W 092
With a typical DSLR, you need a sharp cutoff filter that cuts off at 720nm or above. Hoya calls the sharp cutoff filters "red" from 600nm to 720nm (R-60, R-62, R-64, R-66, R-70, R-72). Of those, only R-72 works well for IR photography with an unmodified DSLR.
Then come the sharp cutoff infrared filters (IR-76, IR-80, IR-83, IR-85). IR-83 is great if you can get it. It gives you monochrome IR like RM-90, but shorter exposures.
triangular said:
I've noticed the RM72 for 77mm thread is somewhat expensive. More so than the Tiffen 87. But I haven't seen anyone using the 87. Does anyone have experience with this filter?
Yes. For most shooting I prefer it, for its "pure" monochrome look. Although I normally use a Lee 87, a Hoya RM-90, or a B+W 093 when I want an "87 family" filter (I cannot stand Tiffen. Ask me why, I dare you
).
There are basically two kinds of filters that you have to worry about. Filters that let through a mix of IR and just enough visible red to make a nice "false color" picture, and filters that let through just IR and make pure IR monochrome pictures.
The pure IR filters include anything with 87 in its name (Hoya 87, H&H 87, Lee 87, Wratten 87) as well as the commonly available B+W 092 and Hoya RM-90. Pure IR filters give you a magenta picture which you can use the camera's white balance, or the PotatoeShop channel mixer to turn into pure monochrome. The IR cutoff frequency is high (780nm to 1000nm, depending on which filter you get) so the IR effect (bright foliage, dark skies) is stronger. Note that some cameras produce slight false color on the 87 filters (Lee, Tiffen, H&H, Wratten). Just enough false color to be annoying in post processing, but not enough to look pretty.
The mixed IR filters include anything called 89B (Wratten 89B) as well as the Hoya R-72, Cokin 007, Heliopan 715, but NOT the B+W 091.
triangular said:
What are your favorites and why?
For "pure monochrome" I like these two:
Lee polyester film 87, because it works well, lasts a long time, uses relatively short exposures, and costs $15. But you need a gel holder. I use a Cokin P system gel holder. Costs like $8. Drop a Lee filter (in a Cokin holder) on the ground and it bounces. Dust it off and go back to using it. Drop a 77mm B+W 093 or Hoya RM-90 on the ground, and even an adult male photographer can cry every now and then. A square filter holder in a Cokin mount is great for IR, because it slides on or off without disturbing the lens hood. And it's not a Tiffen.
B+W 093, because it produces visually near identical results to the Hoya RM-90, but uses shorter exposures.
For a "mixed color" IR filter, I use these:
Cokin 007, because it works in the Cokin holders, is cheap, and survives being dropped pretty well.
Hoya R-72, because I have them in several sizes.
I do not typically use Wratten gels, for two reasons. First, Wratten gels are gelatin, and are very vulnerable to dirt and moisture. Second, Kodak sold Wratten to Tiffen.
For UV work, i use mostly a B+W 403. (you did ask about UV).
