Matt Grum wrote: _julian_ wrote:
My opinion is that the best bang for the buck for M lenses will be the A7 since the larger pixel wells are a more relaxed design less affected by light falloff and color shift. The low-pass filter/IR hot mirror can then be physically removed leaving only the thin IR absorption plate which will dramatically reduce corner smearing following the same principle that Leica use for their digital Ms.
I believe from posts earlier in this thread that the IR absorption layer is between the two layers of the OLPF, and that the second layer of the OLPF doubles as the sensor coverglass. Removing it leaves a very delicate sensor surface underneath.
You would have to then source a replacement IR filter, but if you did this then yes you would reduce smearing with symmetrical lenses, but at the expense of performance with lenses designed for digital. The refractive properties of the filter stack cause a degree of field curvature that lens designers now take into account (attempting to induce the opposite curvature in the lens itself).
Yes the sandwiching of the IR filter appears to be a common according to Canon / Nikon teardowns and literature..
That leaves two approaches to fixing smearing. Either remove all the layers except the first birefringent/sensor cover and then use a regular IR lens-filter on the front of the lens the same way that M8 shooters do. This is non-destructive and called a \'full-spectrum\' conversion by IR guys like lifePixel who offer it as a commercial service.
Alternatively try to substitute that first layer with the IR absorption glass which is a far more delicate and non-reversible action. theSuade says it can be removed using a sharp knife and experience!
Matt Grum wrote: _julian_ wrote:
My opinion is that the best bang for the buck for M lenses will be the A7 since the larger pixel wells are a more relaxed design less affected by light falloff and color shift. The low-pass filter/IR hot mirror can then be physically removed leaving only the thin IR absorption plate which will dramatically reduce corner smearing following the same principle that Leica use for their digital Ms.
I believe from posts earlier in this thread that the IR absorption layer is between the two layers of the OLPF, and that the second layer of the OLPF doubles as the sensor coverglass. Removing it leaves a very delicate sensor surface underneath.
You would have to then source a replacement IR filter, but if you did this then yes you would reduce smearing with symmetrical lenses, but at the expense of performance with lenses designed for digital. The refractive properties of the filter stack cause a degree of field curvature that lens designers now take into account (attempting to induce the opposite curvature in the lens itself).
Yes the sandwiching of the IR filter appears to be a common according to Canon / Nikon teardowns and literature..
That leaves two approaches to fixing smearing. Either remove all the layers except the first birefringent/sensor cover and then use a regular IR lens-filter on the front of the lens the same way that M8 shooters do. This is non-destructive and called a \'full-spectrum\' conversion by IR guys like lifePixel who offer it as a commercial service..
Alternatively try to substitute that first layer with the IR absorption glass which is a far more delicate and non-reversible action. theSuade says it can be removed using a sharp knife and experience!
Matt Grum wrote: _julian_ wrote:
My opinion is that the best bang for the buck for M lenses will be the A7 since the larger pixel wells are a more relaxed design less affected by light falloff and color shift. The low-pass filter/IR hot mirror can then be physically removed leaving only the thin IR absorption plate which will dramatically reduce corner smearing following the same principle that Leica use for their digital Ms.
I believe from posts earlier in this thread that the IR absorption layer is between the two layers of the OLPF, and that the second layer of the OLPF doubles as the sensor coverglass. Removing it leaves a very delicate sensor surface underneath.
You would have to then source a replacement IR filter, but if you did this then yes you would reduce smearing with symmetrical lenses, but at the expense of performance with lenses designed for digital. The refractive properties of the filter stack cause a degree of field curvature that lens designers now take into account (attempting to induce the opposite curvature in the lens itself).
Yes the sandwiching of the IR filter appears to be a common according to Canon / Nikon teardowns and literature..
That leaves two approaches to fixing smearing. Either remove all the layers except the first birefringent/sensor cover and then use a regular IR lens-filter on the front of the lens the same way that M8 shooters do. This is non-destructive and called a \'full-spectrum\' conversion by IR guys like lifePixel.
Alternatively try to substitute that first layer with the IR absorption glass which is a far more delicate and non-reversible action. theSuade says it can be removed using a sharp knife and experience!
Matt Grum wrote: _julian_ wrote:
My opinion is that the best bang for the buck for M lenses will be the A7 since the larger pixel wells are a more relaxed design less affected by light falloff and color shift. The low-pass filter/IR hot mirror can then be physically removed leaving only the thin IR absorption plate which will dramatically reduce corner smearing following the same principle that Leica use for their digital Ms.
I believe from posts earlier in this thread that the IR absorption layer is between the two layers of the OLPF, and that the second layer of the OLPF doubles as the sensor coverglass. Removing it leaves a very delicate sensor surface underneath.
You would have to then source a replacement IR filter, but if you did this then yes you would reduce smearing with symmetrical lenses, but at the expense of performance with lenses designed for digital. The refractive properties of the filter stack cause a degree of field curvature that lens designers now take into account (attempting to induce the opposite curvature in the lens itself).
Yes the sandwiching of the IR filter appears to be be common according to Canon / Nikon teardowns and literature..
That leaves two approaches to fixing smearing. Either remove all the layers except the first birefringent/sensor cover and then use a regular IR lens filter on the front of the lens the same way that M8 shooters do. This is non-destructive and is called a \'full-spectrum\' conversion by IR guys like lifePixel.
Alternatively try to substitute that first layer with the IR absorption glass which is a far more delicate and non-reversible action. theSuade says it can be removed using a knife!
Nov 13, 2013 at 12:52 PM
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