Saturday, October 27, 2018

Globe Flash V3

I have been using the globe flash macro diffuser I made for the past six months. For close in macro images it really proved amazing. However it had a couple annoyances which I finally decided to address:
  •  It had a paper towel on top of it and wouldn't work without it. That I stuck through six months of a camera that ugly is a good sign of how good of images it produced but it did feel silly. 
  • It was useless beyond about two feet. At these distances the images got really hazy. This is an issue it actually shared with the Sony Twin Flash, and Sigma Ring Flash. Light from the flash would interfere with the image since they don't work with a lens hood.
  • It was incompatible with Raynox macro filters. With these on a macro lens you can get about the best magnification which is usable in the field. 
  • Reflections look a bit funny on some reflective subjects because you can clearly see circular shape of the lens. 
  • It does not work with a lens cap.
Two tweaks fixed both issues. First, the size of the globe was increased to 12 inches. This means it is large enough to completely cover the flash from the perspective of the subject. Second was connecting the globe to a lens hood which blocked the light which was making images hazy.

The image quality for 1X macro is about the same as the previous version but without the previous issues.


To build it, I used the following materials:
The steps were pretty simple, although with the tools I had rather time consuming. Simply cut a hole in the acrylic disc for the lens to look through (I used a Dremmel), epoxy the disc to the lens hood, then epoxy the disc to the globe. Then epoxy the globe to the acrylic disc and cut the globe to shape(I used a hack saw). Since polyethylene is notoriously difficult to bond, I briefly. put it in a flame before making the connection.

Thus far this setup has been quite effective. I am a bit worried about the epoxy bond, it seems less sturdy than it was to the previous acrylic globe, but the last one survived six months of abuse so I expect this one will do alright.