I am beginning to read through the outstanding and extensive off-camera lighting tutorials on David Hobby's "Strobist" blog, so that I can take better photos with my Nikon D90. The way I understand it, Strobist is a philosophy of DIY, using found or inexpensive materials over bespoke, and no-brand over brand.
Lighting is a complex subject, and it takes a while to study up on the terminology and terms. For a while, you swim (drown?) in TTL, CLS and Guide Number soup, until it starts to make sense. There are many decisions to be made, including whether to go Strobist (i.e., manual), automated Nikon CLS (Creative Lighting System) or some combination, whether to trigger your strobes optically or via wire or via transmitter, and so on.
I have a Nikon SB-900 speedlight. It is Nikon's latest, a big mother of a flash, and I want to use it off the camera so that I don't fry the eyes of my subjects (only half joking). You can use the built-in flash of the D90 DSLR as a "commander" for the SB-900 and other modern Nikon flashes (SB-800, SB-600, SB-R200). The SB-900 can also act as the commander in either the fully-automated Nikon CLS scenario, or, in a more Strobist-like SU-4 optical-master / optical-slave scenario.
One problem I read about is that when the built-in flash is acting as the commander, of say an SB-900, it will emit pre-flashes to check exposure and so on, and these sometimes can have a negative effect on your exposure meter-wise, or by causing your model to close his or her eyes, or in the case of critters, spooking them away. So, your alternatives in trying to take care of this problem are:
- Get a Nikon SU-800, which is a dedicated commander module with no flash capability. It is sold separately and as part of a macro photography kit.
- Get the 12 dollar bracket-and-screen set from Nikon called the SG-31R, which blocks the pre-flashes. This is just a bracket you slot into your hotshoe, and a connected black screen that hangs in front of your on-board flash.
- Wire up your SB-900 speedlight using a SC-28 or SC-29 cord and use it as the commander tethered to the camera.
- Put a bit of 35 mm film over your built-in flash since it is supposed to allow IR to pass through but block light. Kodak 120 Ektachrome processed unexposed should do the trick.
- Use "flash value lock" to get an exposure monitor pre-flash first, before taking the shot. Less chance of squinting or blinking.
Or you can do some creative, space-saving DIY, and use an inexpensive IR gel filter to block visible light while allowing IR to pass. I recently bought a Lumiquest SoftScreen, which is a compact diffuser sheet designed to make your on-board flash's light softer. It hooks into your hotshoe, and then you hook the other end of the screen onto the housing for the on-board flash.
The on-board flash's light will shine through the SoftScreen's white screen and get diffused. This seems to give better results than the somewhat harsh light from a direct hit from the built-in. When I heard about the purpose of the Nikon SG-31R screen, though, it occurred to me that I could somehow jury-rig the SoftScreen to hold an IR filter using its case, doing double-duty and saving me from having to carry around yet another contraption.
In the end, I bought a 900 yen (about 8 dollars) Fuji Film #92 IR Gel Filter (actually, it filters the light and lets the IR through), at Yodobashi Camera in Shinjuku, Tokyo, on the 3rd floor of the Camera Kan near the large-format equipment. It even has a little paper holder so you don't mess it up with your grimy mitts (perfect for me, what with all that bike grease on my hands!).
The Steps to Pre-Flash Squelch Nirvana
Here's the steps I took to rig up the SoftScreen with the FujiFilm IR Filter:
- Buy a Fuji Film IR Filter at Yodobashi camera in Shinjuku, Tokyo. It was on the 3rd floor, with the large format film cameras.
- Open the filter, and install it in the little paper holder (two cardboard squares with a circle die-cut out). Secure the edge of the filter with a little Gaffer tape.
- Make a cut with an Xacto knife in the bottom of Lumiquest SoftScreen's plastic case (the side furthest away from the flap side), long enough to fit over the housing of the built-in flash (not the flash itself but its cover). Cut through both sides of the case, and secure the edges of the cut with some Gaffer tape to make sure it does not rip. Test that the slit fits over the flash cover.
- Insert the SoftScreen's white screen portion into the case, so that the case flap drops over the black back of the screen, facing the photographer-side of the camera. Align the hole in the screen with the slit in the case.
- Put the Fuji Filter in the case with the SoftScreen.
- Mount the half-encased SoftScreen on your on-board flash.
- Test that the pre-flashes are cut down, but that remote Speedlights still get fired.
- Try also just propping the filter behind the SoftScreen, without the case. I am not sure which is better and YMMV.
At any rate, I hope you Enjoy it!