This is a cheap screw-on filter that has a few different functions. Mine is a “Bower” brand, which I bought from eBay in 2004. Judging by reviews on Amazon of similar products, they show the same characteristics but it depends heavily on the lens you are attaching it to. I have listed my experiences below.

I’ve had a tonne of fun with this filter and I highly recommend it if you are happy to work within its many limitations (and accept the drop in image quality). For a tiny price, you can virtually add a super-wide angle lens, a fisheye lens and a macro lens to your kit.

The filter consists of two parts:

  • A wide-angle component (one piece of glass).
  • A close-focusing component (also one piece of glass).

These screw together to combine the characteristics of the two.

Features

With both filter components screwed together:

  • 0.42x magnification – for huge field of view
  • Very deep depth of field – not infinite though
  • Extremely close focus – can focus on a subject that is touching the front of the glass

With the macro filter component only:

  • 1:2 magnification
  • ~2cm focusing distance

Some things to note:

  • I ordered adapter rings for 52mm and 58mm filters. The adapter rings, like the filter itself, are made of metal and absolutely butchered my plastic filter threads.
  • The supplied covers are worthless. I keep mine in an orphaned sock.
  • There is a built-in lens hood, but it is also worthless.
  • Flare is out of control. If a light source is anywhere within 180 degrees, you’ll be seeing flare in your picture, and it’s not attractive. This makes it not great for taking night photos of bright lights or trails. I have had reasonable success using it for fireworks.

Lens compatibility

Out of all of the lenses I have tested this with, these are the observed behaviours:
 

Canon EF-S 18-55mm f/3.5-5.6 II (58mm thread)

  • Fisheye effect with both components, macro effect with macro component.
  • Fisheye works best at 18mm, sharpness best at f/7.1 (which is this lens’s sharpest f-stop, probably related).
  • Macro works best at 24mm, sharpness is best at f/8, though f/11 has usable depth of field.
  • At 18mm, a lot of the black inside of the filter is visible in the frame. By 24mm, it is mostly gone.
  • There is very visible distortion at the edges of the frame at all focal lengths.

 

Canon EF 50mm f/1.8 II (52mm thread)

  • With both components and wide-open aperture, pictures take on a dreamy look. I’ve only ever made this look good by accident. Effect is reduced as aperture is stopped down, and images are clear by f/8.
  • With macro component, I could not get a usable image at any aperture.

 

Canon EF 75-300 f/4-5.6 III USM (58mm thread)

  • No fisheye effect with this lens.
  • Have not tried macro component with this lens.

 

Canon EF-S 15-85 f/3.5-5.6 USM IS (72mm thread via step-up ring)

  • Since it is designed for a 58mm thread, there is huge vignetting due to the step-up ring.
  • Other than above, shows similar fisheye behaviour to the 18-55.

Post Processing

I’ve had reasonable success using Lightroom 3/4 and lens correction presets. Instead of using the preset for the host lens, I’ve had good results using the Sigma ultrawide presets – 8mm, 10mm and 12-24mm profiles.

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