two films and a digital

Recently I took my Panasonic G1 my film EOS and 2 films with me to the park for some quick test shots. I was after a few things:

• some exposed negative and some exposed slide to compare with eachother
• to then send these films to a fellow to compare his Pacific scanner with my Nikon LS-4000
• and to compare my G1 with what film can give

I thought when I started putting this together that I'd use 200 ISO as my reference as the G1 is reportedly a native 200 ISO sensor. I picked Sensia (a very commonly available Fuji 200 ISO film) as my negative and Sensia as my slide. I was only able to get this in 100 ISO in my dinky-fart-town here in Finland.

In particularly interested to compare 35mm full frame film with a 21mm wide angle lens prime to the Panasonic with a 9-18mm zoom at 11mm. I had previously seen that my 10D was very close to film but the G1 is a latest model camera and at 12 megapixels in a 4/3 format quite at the cutting edge.

Ok ... here's the slide scanned (and nothing done to it).

[for those who are interested, I have my scanner software set to put the image into Bruce RGB and I then assign that profile when it gets into photoshop. I then convert to sRGB for uploads or use screen grabs, my monitor is Spyder calibrated but I don't know if yours is]

[don't forget to click on any of these images to download the full size]

now, lets zoom in to the patch of red leaves in the middle (to 50% of full resolution).


and compare this to the previous examination of the Neg and the G1



Now firstly I think its important to say that my LS-40 scans a full frame of 35mm to about 5570 pixels wide (4000 Dots Per Inch scan of 1.4 inches is 5600 ... right)

This means that the digital capture of the film will be more greatly magnified than the sensor captured information. So in the previous examination I scaled them to be the same - 4000 pixels wide. I guess that I should do the same here to make direct comparisons with the digital more simple, but the reality is that life is not simple, scans of 35mm film will not neatly fit the mould of digital and so we have to make sence of this somehow.

Probably one of the first things you may notice is how similar the digital is to the negative, but how much darker and inky the slide is. This goes back to the fact that slides are designed with projection onto a screen in mind, while negative is designed to make a print on paper. This is not an insignificant difference.

Ok ... so lets get into pixel peeping and look at 100% views of what we got (100% means one pixel in the file maps to one pixel on your screen.

Slide

which is a segment from an original which is 5573 pixels wide, so it looks bigger. It also looks softer as it hasn't been sharpened.

G1

which is a segment from an image which is 4000 pixels wide and has been sharpened carefully.

It seems to me that the slide image is somehow softer than the image from the digital file (and the image from the negative). Certainly the colour rendition of the digital is more pleasing to my eye than that of the Slide.

One could argue that the digital image seems sharper as it is of a lower magnification, but scaling the slide scan down doesn't seem to make much difference. Possible answers to this could be:

• scanner focus was off
• the focus of the lens was off

To answer this I can say that I specifically chose the red bushes as my focus point for scanning, and used Nikons focus system to to that.

On the subject of focusing, I can report I focused carefully on the screen as I could, and I focused manually. As well, Depth of Field calculations for a 21mm lens at f 5.6 suggest that assuming I focused on something which was about 6 meters away (the trees were a bit further away) that the front of the focal zone would be about 3 meters before me through to infinity. This sort of rules out focusing error here.

Interestingly I have observed exactly this effect in every compairson I have done of Negative VS Slide film.

Ok, lastly ... I think that its fair to say that comparing non sharpened scans to post processed digital is a little difficult to do. So below I have done the following:

• scaled the TIFF from the G1 up to be the same size as the image that comes from the LS-4000 scanner.
• I have colour balanced the scanned slide to be as close in hue to the TIFF as I could
• I applied some curves to darken down the shadow details in the TIFF (as the shadow detail was better than the slide was)
• I applied some strong sharpening and local area contrast enhancement on the Slide scan

[note: the G1 file was a single raw image processed using a flow of dcraw to convert to linear TIFF -> Photomatix to apply careful tone mapping -> photoshop to apply curves and colour balance, there was bugger all sharpening done]


I still think that the G1 comes ahead of the slide, both in colour and detail. As well the Slide actually runs out of dynamic range before the G1 does ... although not before negative did ;-)

note the clarity of the grasses and the leaves. There was no wind on the day.

Certainly the scanned 35mm file will be larger (more pixels) than the G1's file, but the G1 file is so clean and copes with a smidge of upscaling no problems. So when it comes to printing and detail capture it would seem that the G1 and the lenses available to it can at least equal that of the 35mm system. Without a doubt (assuming well exposed images to start with) its easier to get a good printable image from the G1 than it is the 35mm film.

... for my money I'll be using the G1 from now on and using the 35mm for black and white only.

Hope that was useful to someone.

Stay tuned for a scanner comparison in a few weeks!

Negative film scans on Nikon Coolscans

Scanning negative film is (apparently) not a straight forward thing, and perhaps its hindered by the (lack of) understanding of the media as much as the software that is supplied.

For quite some time people have debated back and forward about which way is the best to remove the orange mask in Negative film and which software works best. After around 10 years of scanning my own films I've come to the conclusion that working with negative is not as hard as it seems and that all the 'automation' and funky converters just get in the way of doing a straightforward job simply.

The key point here in this article is why you should never send a machine to do a humans job.


After working with negative in the darkroom for some time (as well as working with things like densitometers) I'm familiar with the sorts of ranges of light that a Negative can actually capture. I know that scanners can capture this density range (because slides have a greater one), but for some reason when I use my scanner supplied software to scan a negative it always washes out areas which I know it shouldn't (based on the negative).

The figure to the left is a comparison of the results obtainable from a very contrasty negative using two slightly different workflows.

Both are scanned using the software supplied (in this case Nikon Scan 4.0.2), however in the top image the software was set to be scanning a negative, while the bottom one is obtained with the software told that I am scanning a positive.

I don't know about you, but aside from the areas in shadow (where I biased my exposure towards) I think that the software has done a shitty job. To me what's wrong with the to image is:

• the sky is washed out
• the buildings are colour cast and not showing their true colours
• image looks muddy
• rooftops blowout
• shadows block up

So how do I do it?

Surprisingly its not hard, so here goes my attempt at conferring a trade secret to you guys. It all comes down to understanding your tools. In this case the tools are:

• negative film
• scanner operation

Firstly, negative film is not some sort of mythically complex thing and there is much dribble written about the "orange mask" (insert feelings of fear and confusion related to ignorance). Lets ignore almost everything about negative film apart from two things:

1. its a negative - this means that dark things will appear light and light things will appear dark
2. for various reasons each of the layers of Red Green and Blue sensitive material have different density levels (meaning are of unequal darkenss when you hold them up and look at them)

This brings us to the first problem that you will encounter, when using the SA-21 the software trying to scan Negative as Positive the stupid software will not properly sense the boundaries between the negatives. This can happen anyway with particularly dark strips of slides anyway (like shots of the night sky) so its well to know this trick anyway.

Under Scanner Extras you you will find the boundary offset adjustment slider. Just give this a tweak one way or another to align the border.

Ok, now that problems solved ... lets move on.

So lets load a negative into our film holder and take a look at it.

Now if you set your scanner to positive and preview I'm sure that it'll look just like the image to the left.

Now heres where we do the important thing, go to your histogram control and select (as a start) the blue channel. Notice how much of the selected preview image is bunched up over to the left? Well that's because the blue channel has the shortest range in ability to record the scene. Now that doesn't mean that it records less information, just that it records it over a smaller range of density changes. If I cycle through the Red Green and Blue for this particular negative I get the following:



You might notice that there are quite similar shapes to each of them and all three have a similar peak at the brightest end. This actually represents the full amount of information recorded on the film for each channel. They are not the same because its Negative and not Positive (or Slide film). So each channel has by the nature of the film a different appearance. So lets adjust each of them (meaning each of Red Green and Blue) and have a look at what that does.

To do this, grab the sliders and move the dark and light levels to more neatly encompass the 'hump' in the exposure. Don't go too far and start to clip off the ends because even if there is nothing useful there this will be better dealt with using curves later.

Take a look at the image to the left here to get a guide on how far to take that. Now repeat this for the Green and Red channel (although the red will be less important as it has the widest range and is already spread fairly widely).

So notice in the figure to the left that the scanning range is now much tighter around the blue area and also that the image now looks much more like a simple negative of what you'd expect an image to look like? When you are not sure how much data to encompass in this try leaving a little more of the boundarys in so that you will see at what level that is in the histogram. This will appear as a new 'peak' in the graph at the lighter end and will show you the level of the deepest shadows. This will require a little learning and intuition which is something that machines seem not smart enough to do at the moment.

From here its all down hill, as back in photoshop you simply (note: order is reasonably important here):

1. assign the colour profile which matches the settings in Nikonscan (in my case I set it to Bruce RGB, but assign don't convert)
2. invert image (it will now start looking really close)
3. next, either trim up the levels by hand or use Auto Color Balance to get the image 90% right straight away. (Note: tricky images with lots of irregular colours will fool many Auto Colour Balance systems so you may need to then balance with careful levels and curves adjustment).
4. lastly you can choose to tweak Hue and Saturation levels for (typically) Red, Yellow, Cyan and Blue. This last step is often only by a small margin and subject to taste. I often apply only a few increments of change in red and yellow and blue.

That's it ... job done!

---

PS: since this post comes up in my top 10 now and then, here is some links to other posts which may be helpful to a scanner: You might find these quick notes interesting too:

• my colour negative workflow (which is similar)
• registration problems on Epson scanners and why you shouldn't go too far in trying to adjust this or that because when you improve focus you may disturb registration
• using your scanner to understand film density.
• driving your scanner software differently to effect some changes in scanner side exposure on Epsons (meaning better noise characteristics in the dense areas of your negs).
• don't forget colour management on your Epson (its not where you might think it is)
• a more detailed examination of scanning Neg as Positive here
• using the Epson for bulk scanning of 35mm colour neg (and getting your desired settings applied across all evenly)

Naturally, as always, feedback and comments are welcome

Epson flatbed film scanners (why improving them is not as simple as it looks)

I've got a couple of these scanners (4870 and 3200) which I use for scanning 4x5 film and more recently 6x9 and 6x12 120 film. While they're quite good up to (somewhere around) 2400 dpi, I don't think there would be many people argue that they go beyond this. The wise (in my opinion) are content with 2400 or less.

An area which is hotly contested is the benefits of adjustment the height of the film holders to obtain better focus, of course I've tried that too. I had performed some careful measurements and found that a small raise in my film holder position improved my focus. Importantly (we'll see why in a sec) I mainly use black and white 4x5 negative, with the occasional use of colour.

It was when scanning a 4x5 colour slide recently that I made an interesting discovery and I've come to the (more or less final) conclusion that while there may be gains to be had in focus, but that there will be other problems introduced by this.

Firstly I discovered this issue by observing a scan of this image which I took earlier this year in the beginning of spring. Its taken with my 4x5 camera, with a coated Fujinon 90mm f8 lens. The exposure was made on Fuji Provia RDP-III.


Looking around the image I noticed that there was some strong chromatic aberration appearing on the scans when magnified as you can see to the left here. This is what I was seeing when magnifying a 1200dpi scan (it requires less magnification when scanning at 1600, 2400 or 3200). Certainly this was sticking out like "prawns eyes" because of the high contrast background of snow.

My first thought was "shit, is my lens this bad?"

So I whipped out my x10 loupe and couldn't see a trace of it on the film. I split the channels to see what was there for each of the R G and B bits. And well I found something I was not expecting.

There is distinct spatial movement between the pixels for R G and B!


Dam!

Above is an animated GIF of each of the colour channels separated. If you wish to look at one of your own images more easily, try cycling through the colour channels (in Photoshop for instance, just press Ctl and cycle through the numbers 1 2 3 on your keyboard).

Looking around the scan I found also, that the effect was not evenly distributed, with left side migrating left to the outside, the center seems to just grow mildly around the axis, and with the right side moving to the right.

Left


Center


Right


What is causing this?

Well, really I don't know, but my working theory is that the difficulty is created by two physical aspects or the scanner;

1. the scanner head is actually not exactly the same size as the image that is scanned, meaning that light from the film travels at different angles to the sensor (see figure to left)
   
2. the sensor is a evenly spaced repeating array of RGB points.

The scanner has in fact an array of 3 distinct sensors placed in separate (although adjacent) locations a red green and blue sensor. So, the data from these adjacent physical positions must then be mapped in single physical space to create a single RGB pixel. This is like the demosiacing that is done on bayer arrays on digital cameras.

Now the next part of the equation comes from the fact that light from the light source is not parallel to the scan head. This creates a complex problem for remapping these as pixels because if you alter the distance between the film and the sensor, the angle will alter at the edges. So while you might be able to perhaps improve the focus you will alter the physical angles, and thus the physical locations of where R G and B are.

I'd have thought that Epson would have accounted for this in their spatial remapping, but they must have decided that the calculation was too complex. I scanned the following to demonstrate just how much angle we're talking about here. Notice how the inside of these knobs (three identical 3-dimensional objects) shows that the scanner is viewing them from the side on the edge of the scan area, and directly below in the center.



Normally you'd not see this when scanning a single dimensional (flat) object like a piece of paper. I think its pretty obvious here that the angle of view changes at varying angles as the distance from the center is increased, not to mention that the effect is different in different locations NB its not uniform.

Meaning that its not easy to just fix by nudging pixels, because if you then need to nudge left side differently to right side, and alter the amount as you move outward in the image. Worse, if you then change the height of the object from the standard location (where prehaps the design is intended to converge the points) to any 'focus sweet spot' then you'll be increasing your aberration effects.

I actually have made adjustment on my focus with stand-off's attached under the film holders to raise it. I tried removing them and found that focus was worse generally, but the above RGB effect was worse in some areas, while better in other areas ... you win some you loose some.

Lucky for me none of this applies when only using black and white. I've found that putting the scanner into black and white mode uses only the green layer, so no remapping of RGB pixels locations is not needed. So this scanner makes a nice well priced black and white film scanner!

But in terms of post construction adjustments to attempt to make this scanner better it seems to me that each individual case needs to be examined carefully for focus AND this RGB effect. Perhaps we're stuck with the system as it is for colour and that altering film height for finding focus sweet spot remains mainly a benefit for black and white film.

Anyway, I would love to hear from owners of later models (like the V750) to see if this issues remains there too!

:-)