Sunday, January 24, 2016

Side-mounted Flash Bracket

For sometime, I have been using the traditional arrangement for mounting a flash and Better Beamer above my camera. This works great for reduction of steel eye.

One big problem with this arrangement is balance. The lens is relatively light and the flash exerts a strong lever arm causing the camera to flop forward or backward easily. This undermines the usefulness of the gimbal head. Even without using a flash bracket, the problem remains to some extent.

I recently found that Jobu makes a flash bracket model FB-SM2 intended to mount the flash above a small lens when using a side-mount gimbal head. Conveniently, when using a bottom-mount gimbal, as with my Jobu Jr., use of this bracket places the flash off to the side. This means that the flash's center-of-mass aligns horizontally with that of the lens and the combination can be made to balance correctly! Combined with the replacement lens foot, a Kirk LP-61, this makes for a compact package.

Here is a view of the assembled system. My home-made rain covers still work with this configuration. Yeah, it looks even stranger than a "normal" beamer ... sort of like the Millennium Falcon.

This view shows details of the foot with the cover pulled back. Without the Canon 1.4x Extender, and the zoom lens fully extended, the assembly reaches balance with the front edges of the foot and the gimbal mount plate aligned with each other and the flash bracket shifted to the back end of the upper groove of the foot. Addition of the extender, or pulling the zoom lens in balances even better as it requires the foot to be shifted forward.

Apart from the obvious improvement in balance, there are some pros and cons of this arrangement.
  • Con - This bracket is shorter than my previous Desmond DAFB-01 bracket so the flash is not as well separated from the lens. 
  • Pro - In bird blinds that have windows, I often find that I have more horizontal room to work with than vertical room.
  • Con - In my pop-up tent blind, I have the opposite situation
  • Con - The compact configuration makes it harder to spin the manual focus wheel. This was already a problem and, frankly, is a very disappointing aspect of the Mark II 100-400 lens.
  • Con - gravity may be able to twist the flash mount so that it causes the flash to point down too much. In the vertical position, gravity also causes the flash to sag down into the correct position. This no longer happens. The net effect is that the flash wants to point a bit down and to the left of frame center. I am playing with some shims to improve this. It is probably the only reason that this bracket arrangement may fail to work.
  • Con - The old bracket provided a better carrying handle.
  • Pro - With the flash removed, the assembly is much more compact that with the old bracket.
Update Mar 9 - So far, this system has worked fairly well. Keeping the flash pointed correctly has been an issue as expected. Another, unexpected disadvantage has been the fact that when the bird is close to a background a shadow is cast to the right of the bird rather than below the bird. The result is less natural looking.

Update Aug 3 - I have mostly given up on this experiment, mostly due to the downward flex of the flash.

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