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A Sfeir

New lenses and the future of FF

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But why do your 'confirmed' specs and details keep changing?

 

I suspect Nursie keeps varying the dosage...

 

Regards,

 

Bill

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18 Mpx fullframe sensor

This would be stupid as it would mean that the pixel size would be roughly the same as on the M8 (1.33^2 x 10.5 Mpx = 18.666666666666664). We do not want more pixels we want more light capturing power i.e. keep the no. of Mpx the same. 10.5 Mpx is more than enough for most applications. Increasing the pixel size by 1.33^2 would give about 1 stop extra sensitivity -- possibly more with improved technology since the M8 first appeared.

 

Leica is not stupid as far as I know.

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This would be stupid as it would mean that the pixel size would be roughly the same as on the M8 (1.33^2 x 10.5 Mpx = 18.666666666666664). We do not want more pixels we want more light capturing power i.e. keep the no. of Mpx the same. 10.5 Mpx is more than enough for most applications. Increasing the pixel size by 1.33^2 would give about 1 stop extra sensitivity -- possibly more with improved technology since the M8 first appeared.

 

Leica is not stupid as far as I know.

 

Well said, agree... a hipotetical M9 with current sensor technology, FF AND same pixel per mm^2 would be a costly joke for Leica... I don't think M8 customers would spend a lot just for being able to use their WATE/18/21 as "real" SWAs instead of their current CVs...

Edited by luigi bertolotti

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From sensor generation to generation there are non-trivial improvements in high ISO and signal-to-noise ratio, so even if the pixel size is the same, we might expect significant improvements, for example base ISO 100, very clean 800, or perhaps even better. Look at the jumps in quality in other brands, like Nikon D2x to D3x or in MF, perhaps more relevantly.

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What about DoF?

 

x1.33 gets you 33% more DOF.

 

I think...

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I think it is more complicated. 1.33x makes you go 1.33x further away for the same framing, but the DoF is proportional to the distance squared...

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I think it is more complicated. 1.33x makes you go 1.33x further away for the same framing, but the DoF is proportional to the distance squared...

 

Could be... it's probably not a linear progression.

 

Does anyone have a scientific answer?

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The scientific answer is that the DoF is the same if the sensor size is the same as film. So with a FF sensor you can use your lens barrel markings as they were intended. It really is this simple.

 

To put this into a slightly more scientific framework - the size of the circle of confusion (CoC) is defined such that after the whole reproduction process the images that you produce look acceptably sharp if the focus remains within the CoC constraints. For 35mm (135) film the CoC is 31 micron, for the M8 it is about 23 micron (31/1.33) and for a full-frame M9 it is 31 micron again. The acceptable DoF range is calculated based on the value of the CoC. So we are back where we started.

 

If you prefer pixel peeping then everything changes but that is outside the normal definition of DoF:D

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Won't prove anything here, even if I could, it's Leica's job. This is just information. You believe it or you don't, it's your right.

 

(sorry but no spec has ever changed between posts, only rounded 18.5 to 18mpx. You should read more carefully ;-) )

 

I still stand by my wager to you in the other thread on this. Information is when you can factually prove the M9 specs and availability. What you currently have is rumour/speculation from your source who may or may not be able to back this up.

 

If or when we get a FF M then I'll join you in the queue. I might want to hold off being first in line though if I were you given Leica's new camera release track record.

 

There are very tangible benefits in having lenses that work as intended (I find this true with my primes on FF DSLRs). I'm sure if I'd never shot full frame analogue then maybe it wouldn't be an issue.

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The scientific answer is that the DoF is the same if the sensor size is the same as film. So with a FF sensor you can use your lens barrel markings as they were intended. It really is this simple.

 

To put this into a slightly more scientific framework - the size of the circle of confusion (CoC) is defined such that after the whole reproduction process the images that you produce look acceptably sharp if the focus remains within the CoC constraints. For 35mm (135) film the CoC is 31 micron, for the M8 it is about 23 micron (31/1.33) and for a full-frame M9 it is 31 micron again. The acceptable DoF range is calculated based on the value of the CoC. So we are back where we started.

 

If you prefer pixel peeping then everything changes but that is outside the normal definition of DoF:D

 

Strictly speaking, the circle of confusion, is an optical property of the lens, not the sensor. The numbers you quote above are the circle of confusion diameter limits, which is the largest blur circle that will still be visible to the human eye at a fixed viewing distance (usually 25 cm); there are a variety of formulae used to estimate the circle of confusion limits, and so you will see a variety of numbers floating about. Because depth of field is a perceptual thing, and optical physics equations get awfully messy awfully quickly, the formulas are qualitative expressions (and not necessarily even 'scientific'), not quantitative ones. If you are of the mathematical bent, http://www.largeformatphotography.info/articles/DoFinDepth.pdf is a great article on depth of field, and fairly comprehensive.

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Could be... it's probably not a linear progression.

 

Does anyone have a scientific answer?

 

More or less, DOF is inversely proportional to the format size, assuming same final viewing size....

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All of the math aside, the reduced sensor size does not change the DOF of the lens, it stays the same. But because of the crop factor you end up with DOF that is different from what you would expect with a FF camera.

 

As an example, a 35mm lens on a x1.5 sensor gives you the FOV of a 50mm, but the DOF of the 35mm.

Edited by thrid

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If you are of the mathematical bent, http://www.largeformatphotography.info/articles/DoFinDepth.pdf is a great article on depth of field, and fairly comprehensive.

 

Thanks for the link.

 

However from that article:

Circle of Confusion

 

A photograph is perceived as acceptably sharp when the blur spot is smaller than the acceptable circle of confusion. The size of the "acceptable" circle of confusion for the original image (i.e., film or electronic sensor) depends on three factors:

1. Visual acuity.

2. The distance at which the final image is viewed

3. The enlargement of the final image from the original image.

Or put differently it does not depend on the "optical property of the lens". It depends on what people chose to define as the acceptable sharpness of a standard print, held at a standard distance. Whether we feel that this standard is acceptable or not is a different discussion.

 

I did some analysis of this myself, see here (pdf file) and here (excel sheet). Which may be usefull for the mathematically inclined.

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I was particularly interested in the concept of diffraction limited DOF, Stephen.

I was able to produce it clearly last week, in this 100% crop of a 24 Summilux test shot: I would put the DOF at less than 15 mm, illustrating the relationship between DOF and enlargement. This is the DOF produced by the pixel size of the sensor.

Edited by jaapv

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Interesting result Jaap!

 

I guess that if you zoom in on the image the pixel pitch of the sensor starts to become the limiting factor at about 14 micron or so (2 pixels).

 

Using the spreadsheet at 24 mm, f/1.4 and CoC = 14 and focus distance 0.7 m I get:

2 mm for the diffraction limited DoF

3 cm for the Circle of Confusion DoF

 

Looking at your image 15 mm for the DoF may even be too large.

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It is possibly less. My first impression was 10 mm, but I amended that not to be accused of gilding the lily

The focus distance was about 1.5 meters, this is the full image. Sorry to everyone for posting the images in two threads, however the intent is different.

Edited by jaapv

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I think this site should be set up to automatically delete an entire thread if the phrase "depth of field" and "crop" appear in the same post. We've beaten that subject to death....

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I think this site should be set up to automatically delete an entire thread if the phrase "depth of field" and "crop" appear in the same post. We've beaten that subject to death....

 

I'm glad that this isn't an agricultural forum then!

 

And here in Holland, 'Depth' of field can also mean the pump has broken down!

Edited by Nicoleica
Another synapse fired eventually.

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I think this site should be set up to automatically delete an entire thread if the phrase "depth of field" and "crop" appear in the same post....

Too bad, i planned to unsheathe my math formulas. Oh well...

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I think this site should be set up to automatically delete an entire thread if the phrase "depth of field" and "crop" appear in the same post. We've beaten that subject to death....
Agree. It re-emerges with depressing regularity and the same discussion starts all over again. That is why I proposed to have a sticky thread on this topic some time ago to keep the rest of us sane. I think we have the topic completely covered so it is annoying that the same mistakes crop up ( sorry) over and over again.

 

And I didn't mention the Do* word in this post

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