| Joined: | Mon Apr 2nd, 2012 |
| Location: | South Lakeland, UK |
| Posts: | 4066 |
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I don't know if the LPF has been replaced by a replaceable piece of protective glass. I suspect it has because it will be needed to maintain optical consistency for the digitally corrected optics of modern 'digital corrected' lenses.
There is a little confusion about exactly what the LPF is. On all the cameras I am aware of the LPF performs several functions. It is very slightly etched to very slightly blur the image which falls on the sensor, this cures the moir© effect but also reduces sharpness slightly, except on the D200 where it reduces sharpness a lot. Well that''s my excuse for soft images!!! The LPF also has strong UV and IR Filtration because unlike film, sensors are very sensitive to IR and UV. If it weren't there the image would include the data of the IR and UV spectrums, which apart from confusing the image, would cause blurring because of the focus shift at those wavelengths.
The LPF also has the effect of interfering with the light path and bending the light path at the corners and edges of the image sensor, the further from the axis, the greater the bend. It is the corrections for this effect which justify the 'corrected for digital' label.
I doubt it will have any great effect on the lens hotspot issue, because I believe there will always be a glass screen of some sort over the sensor. But who knows until you try it?
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Robert.