resolution & resolving power of film – part V

Another example:

I’ve printed this image, which I had shot with a Contax G2 and the ZEISS Biogon 2.8/21mm on Fuji Provia 100F, at a size of 1,80 x 1,20 meters or roughly 6 x 4 feet.

This is a 1:1 cutout of the final image marked with the red rectangle in the above image:

Note that the standard viewing distance for an image this size will be 2,16 meter or 7 feet.

Pretty amazing for 35 mm film at times when digital ‘full frame’ reached 34 MegaPixel, which still has to prove its superiority in terms of quality, resolution, tonality, sharpness, etc.

Let’s hope that Fuji will keep producing slide films for many years to come… Buy film to keep the good times rolling!

Analog vs. Digital

If you want to read about an extremely fair comparison and test, you might check this information from Tim Parkin.

Bruce Barnbaum wrote a very interesting article about New Thoughts on Digital Photography - if you think that digital is a creativity solver, this is a ‘must read’ for you!

resolution & resolving power of film – part IV

Geez, just found another one in my archives, but this time from a 35 mm slide film:

– photograph copyright © 1999-2010 by jens g.r. benthien –

Technical data:

• Camera: Contax G2 (read more about the famous Contax G2 here)
• Lens: ZEISS Hologon 8.0/16mm with mounted center filter
• Film: Fuji Provia 100F 135 (35mm)
• Distance of the marked (red rectangle) object 20 meters =  ~66 feet
• Development: E6 by Fuji EuroColor
• Scan: Nikon LS 5000 ED @ 4.000 ppi and 48bit color depth (imagine what a drum scanner would have done to this image)
• Image size: 5.550 x 3.700 pixel = 21 MegaPixel
• File size: 117 MB

Note: I’ve scanned this image 3 years ago, that means with the latest VueScan edition it would be possible to resolve even more details. In addition I have placed the focal plane to the center planter in the patio, not to infinity. Just out of curiosity I now wish I had placed the focus onto the image and made another shot just for comparison purposes.

The red rectangle: I’ve added the rectangle later, so it is an approximation and a tad larger than the crop below.

Postprocessing:

• White balance adjustment
• adding a red rectangle to show the crop area
• scaling
• cropping

The 200% crop of the tiny rectangle in the above image:

Though you can see the grain, you still can identify the objects in the artist painting: a castle, a soldier in the foreground, the palm tree, the bridge, the arcs of the castle, and even the clouds in the sky.

And all this @ 48bit color depth. Mind boggling. I’m still waiting for someone with a 35 mm digital camera to show me the identical fine details and color shades. I guess I’ll have to wait many years to come before this will happen.

A very good, scientific and in-depth article about the resolution of film and digital has been written by Tim Vitale here (it’s a PDF document).

(http://cool.conservation-us.org/coolaic/sg/emg/library/pdf/vitale/2007-04-vitale-filmgrain_resolution.pdf)

resolution & resolving power of film – part III

Now let us take a real world example.

– photograph copyright © 1999-2010 by jens g.r. benthien –

Technical data:

• Camera: Arca Swiss 6×9 November 2009 near Granada, around 3:00 pm
• Lens: Rodenstock Sironar N, 5.6/180mm from 1986
• Film: Fuji Provia 100F 120 (6×9)
• Film Back: Horseman 6×9 with Graflok
• Distance of the marked (red rectangle) object 120 meters =  394 feet
• Development: E6 by Fuji EuroColor
• Scan: Nikon LS 9000 ED @ 4.000 ppi and 48bit color depth (imagine what a drum scanner would have done to this image)
• Image size: 12.827 x 8.551 pixel = 109,68 MegaPixel
• File size: 627 MB

Postprocessing:

• White balance adjustment
• adding a red rectangle to show the crop area
• scaling
• cropping
• conversion to the *.PNG format to avoid *.JPG artifacts

The 100% crop of the tiny rectangle in the above image:

The height of the grey box is around 150 cm = 59″ or almost 5 foot

If you will print this image at a size of 3,46 x 2,30 meters or 136 x 90 inch or 11,35 x 7,5 feet you will have the identical resolution as you have right now on your screen, sticking your nose approximately as close as 50 cm or 19″ to your screen.

To check the resolution of your digital camera, use following specs:

• 35mm full frame sensor, 75 mm lens (note that your camera is limited to 42bit)
• Hasselblad HD3: 48x36mm sensor, 100 mm lens (I don’t know the color depth of this system, but I think to remember it is limited to 24bit)
• Look for a similar scene, with an object of the same height at the same distance.

The result should be obvious.

resolution & resolving power of film – part II

Same location, same time of the day, same lens [ 2.8/20mm ], different media. Left film Fuji Provia 100F scanned @4.000 ppi and 48 bit, right full frame digital @ 100 ISO. The first is the whole image with the red rectangle marking the area of the crop.

the original image

100% crop, enlarged to 200% and then captured with a screenshot.

Left film, right digital.

OK, this is an enlargement to make the better resolution of film visible. There aren’t worlds between the resolution of 35mm film and full frame DSLR with 24 MP. I don’t want to start a war here, I just want to show how well film based photography competes to insanely expensive DSLR systems.

More information is available here: Norman Koren Photography Page

resolution & resolving power of film – part I

Resolution of Film

How many pixels does it take to describe all the detail we can get from film?

Fuji Velvia 50 resolves 160 lppm [ line pairs per millimeter ], Fuji Provia 100F Professional as well as Kodak EliteChrome resolve around 140 lppm. This is the finest level of detail it can resolve, at which point its MTF [ Modulation Transfer Function ] almost hits zero.

Each line pair will require one light and one dark pixel, or two pixels. So you will need about 320 ppm [ pixels per millimeter ] to represent what a Velvia 50 can resolve, or 280 ppm for a Provia or EliteChrome.

Now let’s do the math:

320 pixels x 320 pixels is 102.400 pixels or ~ 0.1MP per mm² .

35mm film format delivers an image size of 24 x 36mm or 864 mm².

To scan most of the detail of a 35mm slide, you need about 864 x 0.1 = 87 MegaPixels.

Agreed so far?

OK, but here is the catch: each film pixel represents true R, G and B data, and not the ‘Bayer pattern’ interpolated data from digital camera sensors. A single chip 87 MP digital camera still can not see details as fine as a 35mm film slide.

Since the ‘lie factor’ from digital cameras is factor 2 [ because you actually need two dedicated pixels to resolve one black and one white square ], we would need a digital camera of 87 x 2 = 175 MP to see every last detail compared to film. However, even ‘Full Frame’ DSLR’s are limited to 24 MP as per today [ 2010-10-07 ].

That’s 35mm film. Now do the math for a 6×9 medium format film. Because medium and large format lenses resolve less detail, I’ll use 120 lppm as a factor.

120×2=240, 240 pixels x 240 pixels is 57.600 pixels or ~ 0.057 MP per mm².

6×9 cm equals 60×90 mm and delivers an image size of 56 x 86 mm or 4.816 mm².

To scan most of the detail of a 6×9 slide, you need about 4.816 x 0.057 = 274 MegaPixels.

To be able to resolve the resolution and detail a modern film emulsion will render, you need a scanner that resolves up to 8.000 ppi or spi [ Samples Per Inch, which is identical to ppi ].

The Nikon Coolscan LS 5000 ED and LS 9000 ED scan slides @ 4.000 ppi. Now let’s see if this will be sufficient for us and convert 4.000 ppi [ pixel per inch ] to pixel per millimeter:

1 inch = 25,4 mm

4.000 ppm / 25,4 mm ~ 157,5 ppm [ pixel per mm ]

A 35mm slide scanned with this resolution will result in an image size of 24 x 157,5 ppm x 36 x 157,5 pm or 3.780 x 5.670 pixels = 21.432.600 pixels or 21.4 MegaPixel.

A 6×9 slide scanned with this resolution will result in an image size of 56 x 157,5 ppm x 86 x 157,5 ppm or 8.820 x 13.545 pixels = 119.466.900 pixels or 119.5 MegaPixel.

Pretty impressive up to this point. However, now let us break the boundaries of the Nikon scanners and turn to a drum scanner.

To resolve full detail of a 35 mm slide, we just have to multiply 36 mm (the long side) x 320 pixels which results in a required scanner resolution of 11.520 pixel for the whole slide.

Now let us convert this into ppi [ pixel per inch ]:

36mm / 25,4 = 1,417

11.520 / 1,417 = 8.130 ppi which is a tad higher than the resolution power of a high end drum scanner.

Don’t try to calculate it for medium format – a scanner to resolve that image area doesn’t exist.

BTW, just compare the camera below to digital cameras. It is almost the same size as a Canon 1 DS MK III or Nikon D3x, but the area of the recording medium is 5,57x larger. Compared to a new medium format digital back the recording medium still is 1,78x larger. Do you really want me to talk about 4×5″, 5×7″ or even 8×10″ cameras?

Conclusion:

When it comes to real world resolution in photography, film can’t be beat until today. I guess many digital shooters who propagate the ‘fantastic resolution’ of their cameras now wish they could buy a film based camera.

OK, I already hear them screaming: “But the lens resolution [ MTF ] of medium and large format lenses is considerably lower than you have taken into account here!” All I can say at this point: please, just do the math again with lower resolving powers by applying the formulas posted above.

Film will prove its superiority in any aspect, even if the resolving power of the lenses will be lower.

[ One of my Fuji 6x9 cameras with the fantastic, razor sharp EBC Fujinon 3.5/90mm lens - a true beast in terms of resolving power ]

– photograph © 1999-2010 by jens g.r. benthien –

Additional information: Resolution and MTF curves in film and lenses