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Author Topic: Some new stuff from Erwin Puts  (Read 4815 times)

ErikKaffehr

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Some new stuff from Erwin Puts
« on: December 18, 2009, 01:31:14 am »

Hi,

Erwin Puts has some interesting images from M9:

http://www.imx.nl/photo/leica/camera/page164/page164.html

Several interesting things:

Color moiré artifacts are really obvious
According to Erwin Puts the M9 resolves about the same as modern 100 ISO BW film. He also compares "Orthopan" and that film wins with a broad margin.

Some personal observations:

- Erwin Puts compared the M9 to the D3X earlier and did find the D3X sharper. It would be interesting to have the D3X involved in the comparison as it does have an optical low pass filter which the M9 does not have.

- Another observation is that the test patterns used are very sensitive to aliasing effects. Norman Koren's sinusoidal patterns may provoke less moiré artifacts from the M9.

- Erwin Puts may be right in digital not surpassing negative BW film, but most people actually shoot color. With film we can choose the sensor (film) for the task with digital we are stuck with the sensor in the camera.

- A final observation is that orthocrhomatic film actually pushes the limits as it is not sensitive to red. So it reduces both chromatic aberration and diffraction, the latter because it's sensitive to light with shorter wave length.


Best regards
Erik
« Last Edit: December 18, 2009, 02:09:39 am by ErikKaffehr »
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JohnBrew

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Some new stuff from Erwin Puts
« Reply #1 on: December 18, 2009, 07:50:08 am »

Thanks, Erik for posting the link. I, too, have found using my M3 with Efke 25 and a modern ASPH lens, to produce superior results.

bjanes

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Some new stuff from Erwin Puts
« Reply #2 on: December 18, 2009, 09:50:44 am »

Quote from: ErikKaffehr
Hi,

Erwin Puts has some interesting images from M9:

Color moiré artifacts are really obvious
According to Erwin Puts the M9 resolves about the same as modern 100 ISO BW film. He also compares "Orthopan" and that film wins with a broad margin.

Eric, thanks for bringing the Erwin Puts post to our attention. In addition to your perceptive comments, I would like to add a couple of my own. Puts is using high contrast resolution targets similar to the old US Air Force targets which measure resolution at extinction. Norman Koren has pointed out the paradox of measuring resolution where it disappears and ceases to exist. Modern theory using MTF stresses the importance of contrast at lower resolutions. In analyzing the performance of optical systems with 35 mm style cameras, resolution at 10 lp/mm is often given more weight than resolution at 40 lp/mm.

Digital sensors give good MTF at lower frequencies and the image breaks apart completely at Nyquist. MTF with film degrades more gracefully. Rather than using MTF at high frequency to judge the systems, I think one should also look at MTF at lower resolution in the range of 10 lp/mm for full frame sensors. Those USAF charts are so mid 20th century.

Bill
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skid00skid00

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Some new stuff from Erwin Puts
« Reply #3 on: December 19, 2009, 06:51:59 pm »

Film has higher resolution on test targets with high contrast.  It resolves a *lower* resolution with low-contrast details.  Digital does not suffer from this phenomenon.  Film's lack of flatness, and the thickness of the silver-carrying layer also end up blurring the captured image somewhat.

I find the ever-present softness of fine details recorded in film to leave me wanting digital.  (At least when comparing *resonable* film-to-digital sizes.)

When Adobe figures out how to give us adjustable contrast that continues to emulate film's tone curve, many more photographers will embrace digital capture.
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ErikKaffehr

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Some new stuff from Erwin Puts
« Reply #4 on: December 19, 2009, 10:09:49 pm »

Hi,

Resolution has little to do with our perception of sharpness. For me the most obvious difference from "normal" film is that digital has very little noise at low ISO. In the chemical darkroom we had several steps involving loss of sharpness. Lens, Film, enlarger (or projector) and paper. In the digital workflow there are similar losses but they can be compensated for by sharpening.

I don't really buy into the tone curve thing. With the usual tools we have we can apply any tone curve to digital. The only characteristic of film that can not be reproduced is the saturation characteristics of film in the extreme highlights.

The film based images Erwin Puts has on his pages were processed in the wet darkroom and than scanned from print.

One reason that the digital images are really ugly is that the Leica M9 does not have optical low pass filter, which causes aliasing artifacts. Erwin also made everything possible to maximize moirés, high contrast USAF style targets parallel or perpendicular to the sensor cells and extremely sharp lenses.

Best regards
Erik

Quote from: skid00skid00
Film has higher resolution on test targets with high contrast.  It resolves a *lower* resolution with low-contrast details.  Digital does not suffer from this phenomenon.  Film's lack of flatness, and the thickness of the silver-carrying layer also end up blurring the captured image somewhat.

I find the ever-present softness of fine details recorded in film to leave me wanting digital.  (At least when comparing *resonable* film-to-digital sizes.)

When Adobe figures out how to give us adjustable contrast that continues to emulate film's tone curve, many more photographers will embrace digital capture.
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250swb

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Some new stuff from Erwin Puts
« Reply #5 on: December 20, 2009, 04:11:49 am »

Quote from: skid00skid00
When Adobe figures out how to give us adjustable contrast that continues to emulate film's tone curve, many more photographers will embrace digital capture.

There are Photoshop plugins, called 'Silver Efex Pro' and 'Colour Efex Pro' that have (amongst many other functions) typical tone curve profiles and grain data (acutance, size etc) to match 18 B&W films and 33 colour films. There is no real reason your digital image can't look like Ektachrome, or Tri-X or indeed customize your own, you could have the tone curve and saturation of Velvia with the grain of Superia 1600 (yuk). The price of the plugins is soon offset by the money saved in film and processing.

As for your worry about a lack of anti-aliasing filter in the M9 Erik, I can assure you lab tests and real world experience diverge greatly. After a few thousand exposures I have yet to see evidence of any problems caused by this, although I am absolutely sure one day I will. Its the same level of image screw up that will happen one day in any field and however careful you are, like you over agitate the film a fraction, or the developer is one week to old. The only difference is that its related to the single image in digital (and you have no control over it anyway), not the entire 36 exposures. So the M9 is definitely a case of the glass being half full, and not half empty as a re-interpretation of Puts and an axe to grind might make people imagine.

Steve

ErikKaffehr

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Some new stuff from Erwin Puts
« Reply #6 on: December 20, 2009, 04:40:23 am »

Hi,

I discuss the aliasing issues mostly because they are pretty bad on the Erwin Puts page. The reason is in part, as I try to point out, that the patterns used are enhancing moiré type artifacts. There are many reasons that they can go unnoticed in real life photography.

One is test patterns, moiré typically shows up when sensor pitch is similar to the pitch of the test pattern. If you shoot portraits for instance aliasing would probably show up in very thin strains of hair and they would not be continuous.

The other issue is that moiré artifacts would only be visible in large enlargements and with absolute perfect focusing at moderate apertures.

Best regards
Erik


Quote from: 250swb
There are Photoshop plugins, called 'Silver Efex Pro' and 'Colour Efex Pro' that have (amongst many other functions) typical tone curve profiles and grain data (acutance, size etc) to match 18 B&W films and 33 colour films. There is no real reason your digital image can't look like Ektachrome, or Tri-X or indeed customize your own, you could have the tone curve and saturation of Velvia with the grain of Superia 1600 (yuk). The price of the plugins is soon offset by the money saved in film and processing.

As for your worry about a lack of anti-aliasing filter in the M9 Erik, I can assure you lab tests and real world experience diverge greatly. After a few thousand exposures I have yet to see evidence of any problems caused by this, although I am absolutely sure one day I will. Its the same level of image screw up that will happen one day in any field and however careful you are, like you over agitate the film a fraction, or the developer is one week to old. The only difference is that its related to the single image in digital (and you have no control over it anyway), not the entire 36 exposures. So the M9 is definitely a case of the glass being half full, and not half empty as a re-interpretation of Puts and an axe to grind might make people imagine.

Steve
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NikoJorj

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Some new stuff from Erwin Puts
« Reply #7 on: December 20, 2009, 10:47:55 am »

Quote from: ErikKaffehr
One is test patterns, moiré typically shows up when sensor pitch is similar to the pitch of the test pattern. If you shoot portraits for instance aliasing would probably show up in very thin strains of hair and they would not be continuous.

The other issue is that moiré artifacts would only be visible in large enlargements and with absolute perfect focusing at moderate apertures.
Quite true - the main real-world occurences of moiré I can think of are architecture (tiles roofs, brick walls...) or fabrics - it just depends on specialisation, but it is globally rare.

There is imho a last simple factor for these ugly moirés : Erwin Puts compare a color rendition of the digital image with B&W films. Apples to Bratwurst.
If you desaturate the M9 image (and I'd guess that's what one would do one way or the other, if the M9 is seen as a replacement for B&W-loaded M?), moiré is waaaaay less objectionable...
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Nicolas from Grenoble
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ErikKaffehr

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Some new stuff from Erwin Puts
« Reply #8 on: December 20, 2009, 11:35:57 am »

Äpfel und Bratwurst ... ;-)

Erik

Quote from: NikoJorj
Quite true - the main real-world occurences of moiré I can think of are architecture (tiles roofs, brick walls...) or fabrics - it just depends on specialisation, but it is globally rare.

There is imho a last simple factor for these ugly moirés : Erwin Puts compare a color rendition of the digital image with B&W films. Apples to Bratwurst.
If you desaturate the M9 image (and I'd guess that's what one would do one way or the other, if the M9 is seen as a replacement for B&W-loaded M?), moiré is waaaaay less objectionable...
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gingerbaker

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Some new stuff from Erwin Puts
« Reply #9 on: December 23, 2009, 11:12:22 am »

Quote from: NikoJorj
Quite true - the main real-world occurences of moiré I can think of are architecture (tiles roofs, brick walls...) or fabrics - it just depends on specialisation, but it is globally rare.

There is imho a last simple factor for these ugly moirés : Erwin Puts compare a color rendition of the digital image with B&W films. Apples to Bratwurst.
If you desaturate the M9 image (and I'd guess that's what one would do one way or the other, if the M9 is seen as a replacement for B&W-loaded M?), moiré is waaaaay less objectionable...

That's what I was thinking as I read the article.  What would the M9 results look like if all one looked at was the luminance channel or the green channel?
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NikoJorj

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« Reply #10 on: December 23, 2009, 04:17:10 pm »

Quote from: gingerbaker
What would the M9 results look like if all one looked at was the luminance channel or the green channel?
Like that. Apart from the 45° patterns, I don't find it so ugly.
« Last Edit: December 23, 2009, 04:20:56 pm by NikoJorj »
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Nicolas from Grenoble
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