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K.Spacey - K-PAX
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Visual inspection of film

I decided to do a quick visual inspection of the developed films first. Now although viewing of the film through a 10x loop can already reveal some first impressions of accuracy of focusing and (size of) grain structure, these low ISO film are not particularly suited for such an evaluation, due to their very fine grain. However, since I do not own a microscope, I therefore decided to put all films in my Durst M670 BW enlarger, setting the enlargers head in it's highest position for maximum magnification. Using a grain focus finder thus allowed me to examine the grain structure in much more accurate way. A quick dirty calculation based on the actual size of some of the test patterns on the test chart showed me this equated to roughly a 75x magnification. The Kodak Ektar 100 film proved to have a very fine grain structure indeed, but Velvia 100 seemed to be on par with it. If I had to make a grain size ranking based on this visual inspection, it would look like this:

  • Kodak Ektar 100 / Fuji Velvia 100 - finest grain
  • Kodak Portra 160VC
  • Kodak TMax 100 - coarsest grain

Of course, comparing silver grain based B&W film like Kodak TMax 100 with dye based color negative / positive films is difficult, as the dye clouds of color films have smooth, diffuse and thus indistinct edges, whereas the silver grains of B&W film, at least at these magnifications, tend to appear solid and hard edged, causing a more distinct and coarser looking grain pattern.

In addition, there are many different ways to develop B&W film, using special developers, that may lead to much finer grain or smoother edge contrast, like specially developed fine grain developers and staining developers. Using standard Kodak D76 developer in accordance with Kodak recommended standard development will probably not lead to the finest grain result. Yet my intention was not to achieve the finest grain possible from TMax 100 at all cost, but rather to mimic an average photographer's result of this film.

Analysis of grain structure

To judge the size and structure of the filmgrain / dyeclouds of Ektar 100 and the other films in this test, I have included a number of actual pixel, 100% viewing crops below. Each film's image represents three crops from different parts of the test chart. I included bits of the smooth "grey" background of the test chart as well. As you can see from the images, what may appear grainy on such a smooth background, actually doesn't have to look bad in an actual photo. Just look at the difference between the smooth areas and the crops of pebbles and the wall. Do also notice there is quite a lot of color noise in these images, especially the ones of the color negative films Ektar and Portra, more on this topic in one of the next pages.

All results at the full 8000 ppi scanning resolution. To make the judgment of the grain structure a bit more easy, I have sharpened all of these scans in Photoshop using Unsharp Maks and the following settings:

  • Amount: 200
  • Radius: 0.7
  • Threshold: 2

Now in most cases, this is slightly beyond what I would consider a save level of sharpening, but it helps to bring out the grain structure, and that is the main goal of this section. And as you can see with some of these scans, like the ones from Ektar 100 and Velvia 100, it actually doesn't yet cross the border of ruining the image. These images still look relatively smooth, especially Velvia 100.

Do note though, that at 8000 ppi, we are reaching the absolute limits of what 100 ISO film can deliver. I would normally scan these films at a more realistic 2000 to 4000 ppi maximum, leading to a much more smooth and pleasing scanresult.

Kodak Ektar 100

Kodak Portra 160VC

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Fuji Velvia 100

Kodak TMax 100

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As you can see from these crops, my initial impressions from the visual inspection of the 4 film types is quite good. The ranking I made still holds, with Kodak TMax 100 being the coarsest grain, Kodak Portra 160VC intermediate, and Kodak Ektar 100 and Fuji Velvia 100 finest grain. Interestingly though, the scan of Velvia 100 slide film appears much more smooth, although the dye clouds don't appear to be much finer than the second best film, Ektar 100, especially judging the visible structure in the smooth grey background areas. So what might cause this? Well, have you ever had a real good look at color negative film? Of course you've noticed it just looks brown / orange, but did you realize the consequences of that? There is one aspect in favor of slide film scanning: slide film has a full contrast range from pure black to white, whereas color negative film only has a very limited range of colors to be scanned. Just look at the examples below:

Kodak Ektar 100 negative

Limited range of colors in a color negative, no black and white

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Fuji Velvia 100 slide

Full range of colors in slide film, from dense black to white (blank film)

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Kodak TMax 100 negative

Large dynamic range from dense black to white (blank film). Please note that this image does not contain any real highlights, so the deepest blacks of a B&W negative at highest silver density are not visible in this example.

Now a scanner doesn't need to do a lot to faithfully reproduce a slide, besides capturing the pixels. However, with color negative film, the limited contrast range of the original negative needs to be expanded to a full contrast range from the deepest black to pure white. It is the equivalent of stretching an elastic band 10x. Now each tiny error in determining the exact value of the Red/Green/Blue (RGB) values of the pixels of a color negative gets expanded / exaggerated as well in the process. Hence, almost inevitably, a high resolution scan result of color negative will look a bit more "grainy" as well, as these pixel errors have been enhanced as well. I think this is the main reason why the Velvia 100 results looks more smooth, compared to Ektar 100.

It is also the reason why it's so important to have dedicated color calibration profiles for each and every color negative film being scanned with a certain scanner, whereas for slide film this is less of an issue. If the color calibration profile doesn't match the contrast range and color saturation of the specific color negative film, the scan's colors will inevitably be "off" / wrong.

In addition to this, it is in this area of very accurate RGB pixelvalue scan results, that a drum scanner probably would beat the Imacon, and deliver more smooth results, especially combined with the ability of a drum scan to "hide" grain by changing the aperture of the photo multiplier tube rig. See this excellent reference for a more thorough discussion of different scanner designs and drum scanners specifically: Film Grain, Resolution and Fundamental Film Particles by Tim Vitale.

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