Do you think these LEDs will be good for a nice FTIR effect?
http://www.vishay.com/ir-emitting-diodes/list/product-81011/
Looks like they are pretty bright (typ. 40 mW/sr @ 100mA) and are very cheap. Won’t the higher wavelength (940nm) be a problem?

I have some L-53F3BT at the moment for testing, but they’re not very efficient.

Thanks in advance!

yes you can use them:

use this website to design your electronics:
http://led.linear1.org/led.wiz

now you need an IR-pass filter for your camera. since your LED’s will be generating light at 940 nm, you want a filter as close to that as possible.

LEE #87 begins transmission of IR light from 730 nm....

You can purchase acrylic filters from here:
http://www.knightoptical.co.uk/acatalog/FiltersColourfilters-Acrylictype50x50mm.htm

Their filters begin transmission at 850 nm

Edmund Optics has glass filters (more $$)
http://www.edmundoptics.com/onlinecatalog/browse.cfm?categoryid=10&level=2

to echo nima, sure the 940 nm leds would just do fine, Jeff Han used 880 nm, but still, there have been people that used 940 nm as well, without any problems

@ nima, added your urls to the wiki as well