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Any enthusiasm for the upcoming 1.25/75mm Noctilux?

Linford

By Linford
in Leica M Lenses

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colint544
colint544

I'm skint and won't be buying one. But I think it's great that Leica continue to strive for what's possible with current technology. There aren't too many camera manufacturers who perpetually have som

horosu
horosu

I don't like the idea of big, heavy lenses on a rangefinder. Leica & Zeiss seem to compete for the sharpest, best, heaviest, most expensive lens in any give focal length instead of producing small

pico
pico

No enthusiasm because I doubt it will be more affordable than the Summilux 75mm f/1.4 and given the new optics design of Leica lenses I do not trust it to deliver the aesthetics of Mandler. .

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IkarusJohn

IkarusJohn

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According to my dof calculator, with a 12 micron blur spot, 75mm at 1.2 will have a dof of 2mm at 1 metre; 1.4 has 3mm; and the Noctilux 4mm.  Splitting hairs.

 

For me, the M rangefinder system is best in the 28-90 range.  I seem to like 50s, and having the Noctilux-M 50/0.95 I do want either a 75 or 90; if there was a 75 Noctilux it might be worth it.  I'm currently finding, though, that the Noctilux is better on the SL than on the M, and having the 75 Summilux, I don't need another 75.

 

Peter Karbe apparently dislikes the Mandler 75 Summilux, so a 75 Noctilux could well be on the cards.  If Leica is expanding the Noctilux line, I would have thought a 35 Noctilux would be more likely.

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pico

pico

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According to my dof calculator, with a 12 micron blur spot, 75mm at 1.2 will have a dof of 2mm at 1 metre

[...]

Oh for heaven's sake, John. Do not confuse our honored constituency with metrics. Do you do not know that

they cannot see? What they have are words to direct them to opinions that do not yield evidence.

 

Peace, Bro.

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IkarusJohn

IkarusJohn

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I suspect that John's referring to the Circle of Confusion but it's normally quoted as 0.029 mm for 135 format, which is 29 microns.

 

Pete.

 

Yep, circle of confusion (the confusion could be mine, in which case it's a big circle).

 

To calculate for the SL and M10, length of the long side of the sensor (36mm) divided by the number of pixels along that side (6000), multiplied by 2 (not sure why), then multiplied by 1,000 gives you 12 microns for a circle of confusion on the 24MP sensor.

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adan

adan

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.... multiplied by 2 (not sure why)......

 

Nyquist limit - you need at least two samples per unit of resolution (e.g. 2 pixels for each blur circle, or a blur circle at least two pixels wide) to avoid artifacts and "uncertainty" of what you were really capturing. A blur circle smaller than that will be likely to be rendered as a single pixel (i.e. as sharp as anything/everything else in the picture) and no longer a blur.

 

It's not a totally hard limit - a blur circle 1.4 pixels wide may or may not be rendered as one pixel or two pixels, depending on exactly where it falls relative to the edge between the pixels.

 

Plus, as with any DoF calculation, final image viewing size has to be considered - you'd likely need a print 20 inches/50cm wide to actually see a 2-pixel blur as a blur and not a sharp point. Which is why the standard assumed blur circle for a "35mm image" is the 0.03mm (30 microns) mentioned by lct and Pete (farnz). The vast majority of photographers make smaller prints, where a blur on the original surface (sensor or film) of 30 microns, even enlarged 8x (8x12-inch print) becomes a blur of 240 microns or 0.24mm diameter, and stilll "looks like" a sharp point.

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pop

pop

Posted
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Yep, circle of confusion (the confusion could be mine, in which case it's a big circle).

 

To calculate for the SL and M10, length of the long side of the sensor (36mm) divided by the number of pixels along that side (6000), multiplied by 2 (not sure why), then multiplied by 1,000 gives you 12 microns for a circle of confusion on the 24MP sensor.

The length of the long side of the sensor divided by the number of pixels along that side yields the pixel pitch, i.e. the distance between two adjacent pixels. 36mm divided by 6 yields 6mm; 36mm divided by 6000 yields 0,006mm or 6 micro-meters (μm).

 

Presume for a moment that the width of each pixel is equal to the distance between the centers of two pixels (it's not true, but assume it just for argument's sake). In this case the pixel pitch (6μm) would be the smallest dot the sensor could resolve. Since a circle of confusion which is exactly one pixel wide would not make much sense, you divide the pixel pitch by two to arrive at a more meaningful COC, 12μm.

 

The final multiplication by 1000 turns 6μm into 6 mm, which is clearly not useful. I think this part of the formula must be in error.

 

Traditionally, the COC is reckoned as about 1/1500 of the diagonal of the image, i.e. 0.029mm or 29μm. While this may be a bit generous for today's print sizes, I think it's a more useful size than twice the pixel pitch at 12μm. However, that's a matter of opinion and a factor of 2.5.

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IkarusJohn

IkarusJohn

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Nyquist limit - you need at least two samples per unit of resolution (e.g. 2 pixels for each blur circle, or a blur circle at least two pixels wide) to avoid artifacts and "uncertainty" of what you were really capturing. A blur circle smaller than that will be likely to be rendered as a single pixel (i.e. as sharp as anything/everything else in the picture) and no longer a blur.

 

It's not a totally hard limit - a blur circle 1.4 pixels wide may or may not be rendered as one pixel or two pixels, depending on exactly where it falls relative to the edge between the pixels.

 

Plus, as with any DoF calculation, final image viewing size has to be considered - you'd likely need a print 20 inches/50cm wide to actually see a 2-pixel blur as a blur and not a sharp point. Which is why the standard assumed blur circle for a "35mm image" is the 0.03mm (30 microns) mentioned by lct and Pete (farnz). The vast majority of photographers make smaller prints, where a blur on the original surface (sensor or film) of 30 microns, even enlarged 8x (8x12-inch print) becomes a blur of 240 microns or 0.24mm diameter, and stilll "looks like" a sharp point.

Thanks Andy (& Phillipp) - I was ignoring viewing distance, wanting to concentrate on the digital concept of blur (I think that makes sense). The 3 microns measure lct and Pete refer to relates only to the 18MP based sensors in the M9 cameras.

 

Cheers

John

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Exodies

Exodies

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Never heard that the number of pixels is a factor to calculate the CoC so far but i'm no techie at all.

 

Think of it like this - if your pixels are larger than the CoC then you are not getting all the information your lens provides; if your pixels are much smaller than the CoC then they are wasted. So CoC and pixel size should be in harmony.
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Exodies

Exodies

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Not exactly but the CoC sets upper and lower limits on sensible pixel sizes.

Exaggerated example - if you choose a CoC of one inch then a pixel one foot square or a millimetre square would be pointless.

Edited by Exodies
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