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Handling and Performance
The USB Fever Mini Circular-PL Filter is a circular polarising filter for use with the iPhone 4 and iPhone 4s. A polarising filter is used to reduce reflections on non-metallic surfaces. It's ideal for shooting through glass when the reflection prevents you seeing what's behind. It also allows you to record what's below the surface of water, and the glare reducing factor makes colours more saturated.
The filter with back case costs $38 from USB Fever (or around £27 in the UK via eBay).
- Lens Construction: 2 elements in 2 groups
- Metal mount
- Glass filter
- Dimensions: 19.5mm (diameter) x 7.0mm (length)
- Weight: 3g (lens)
Once in place the filter can be rotated and has a knurled rim to make it easier to grip. It works just like the polariser your use on a standard digital camera and increases saturation while reducing reflections. You can even shoot the cross polarised colours in plastic when using your computer's LCD screen as a background. See article here: Cross Polarisers
The polariser normally has a filter factor which means you have to adjust exposure to compensate. This is usually between one and one and a half stops. As the iPhone is totally automatic you don't need to worry about this, In one of our tests it increased the ISO to compensate from ISO800 to ISO1000. When the filter is attached it makes no difference to exposure when adjusting the filter position.
On the shot with the apple you can see that in the first shot the worktop is darker because the angle means the polariser has killed the glaer there. While on the second shot it's reduced the reflection in the tiles, but has no affect on the worktop. With the glass bottle shots the polariser has dulled down any glare reflections in the glass.
The one main flaw with the filter is it's not wide enough diameter which means the lens sees the edges and results in dark corners or vignetting. This can be cropped off but does mean you're not getting the full capacity of your camera and you'll need to compensate when framing to prevent important detail being clipped when you crop later.
USB Fever Mini Circular -PL Filter Sample Photos
Polariser at maximum setting 1/15 sec | f/2.8 | 3.9 mm | ISO 200
Polariser at minumum setting -1/15 sec | f/2.8 | 3.9 mm | ISO 200
Polariser at minumum setting -1/180 sec | f/2.8 | 3.9 mm | ISO 80
Polariser at maximum setting 1/180 sec | f/2.8 | 3.9 mm | ISO 80
Polariser at maximum setting 1/160 sec | f/2.8 | 3.9 mm | ISO 80
Polariser at minumum setting - 1/160 sec | f/2.8 | 3.9 mm | ISO 80
Cross polarisation using polariser and LCD screen background - 1/15 sec | f/2.8 | 3.9 mm | ISO 400
Cross polarisation using polariser and LCD screen background - 1/15 sec | f/2.8 | 3.9 mm | ISO 250
Cross polarisation using polariser and LCD screen background - 1/17 sec | f/2.8 | 3.9 mm | ISO 400
Cross polarisation using polariser and LCD screen background - 1/17 sec | f/2.8 | 3.9 mm | ISO 320
Cross polarisation using polariser and LCD screen background - 1/15 sec | f/2.8 | 3.9 mm | ISO 500
USB Fever Mini Circular-PL Filter ProsWorks well to reduce reflections
Reduces glare to increase colour saturation
Comes with iphone case
Doesn't add too much extra bulk
USB Fever Mini Circular-PL Filter ConsVignetting in corners of frame
Plastic thread of the case could get damaged by cross threading
|VALUE FOR MONEY|
For more details of the iPhone Polariser visit USB Fever.