Converting negatives to positives in just a few mouse clicks

We all know that film has beautiful colors that cannot be easily replicated with digital cameras. Unfortunately, when I shot my first film roll and got the scans from the lab the results were just awful. So I decided that if you want something done right you have to do it yourself. Here is the setup I bought: Nikon ES2 film holder, and Nikkor 58mm macro lens. 

Digital film scanners have built in profiles that give accurate colors during negative conversion as long as you tell the scanner which film you are using. But I have no such profile.  I needed a procedure that is easily replicated and can be automated using a preset. That is, I needed something that would allow me to invert a whole roll in just a few clicks. After hours of fiddling around here is the procedure I now use.

Below is a negative shot on Kodak Potra 400 shown in Capture One:

The first step is to set shadow and highlight levels in the Capture One levels tool. Set shadow level to 255 and highlight point to 0 for now. An often recommended approach is to set the shadow level by clicking on the orange edge of the negative where the negative was unexposed. The unexposed area is truly black even though it looks orange. This is often referred to as the orange mask of the negative. Even though the black point could be tuned to the unexposed area, I prefer to set black and white points later to achieve the look I want. Here is how an inverted negative looks:

The next step is to set the white point. The color card we are looking at has a white square on it. Incidentally, the two sliders on the white balance tool are the blue-orange balance called temperature, and the cyan-magenta slider called tint. It is the blue-orange slide that will allow us to get rid of the orange mask. This mask makes our positive look blue. Having picked the white square as our white point we get an image that looks too warm. However, the tint is set correctly.

Now adjust the temperature slider, without changing tint, to get rid of the warm look. I find that setting temperature between 1250 and 1400 works well for this film. Tint may need to be adjusted too to somewhere between -15 and -20. It really depends on the color of the light, how the negative was exposed, and the look you are going for.

As the temperature and tint are about the same for all images on the roll, it is possible to convert the whole roll in just a few mouse clicks. It is also true that temperature and tint are reasonably close from roll to roll of the same type of film.

Lets apply our preset to an digitized image and compare to the scan from our local lab. Here is the image from the local lab:

I think that the colors from the lab are fine but there is a distinct lack of dynamic range. The image just has this very harsh look. 

Lets take the same image and apply our Capture one white balance preset. I also adjust the white and black points in the levels tool to achieve the desired amount of contrast and shadow detail. 

I think this result is respectable and certainly better than the local lab. This image has a lot more saturation and dynamic range. I can easily replicate the lab result by turning down the saturation and changing levels to remove dynamic range. In any case, this method is superior to the local lab result. Another advantage of the method is that it is very quick and can be applied to a large number of negatives all at once.

It is important to note that this method does not remove the orange mask properly. The orange mask is more orange in the shadows and less orange in the highlights. Therefore, when you look at our resulting slide you will see that the shadows are a bit orange and highlights are a bit blue. I will describe another method to deal with this issue in another post.

Circle of confusion and the thin lens equation

I have spent a little time working out some rules of thumb regarding depth of field, thin lens equation, lens distortion and compression and a few other obvious things. I find that looking at the math helps with understanding these concepts in depth. The full article can be found here. and I summarize it as follows:

  • Higher resolution sensors can be considered to have a smaller depth of field as images can be enlarged more.
  • Depth of field depends only on the aperture but no the focal length, as long as image size on the sensor is kept constant.
  • Depth of field behind the plane of focus is bigger for short focal length lenses, and smaller for long focal length lenses. Thus, telephoto lenses will defocus distant objects faster.
  • Any two lenses with the same maximum aperture will have identical depth of field. However, long focal length lenses will have a smoother bokeh, and appear to have a shallower focal length due to a narrower angle of view, and the fact that they defocus distant objects faster.
  • Perspective distortion occurs because the derivative of image size w.r.t. object distance is inversely proportional to the square of distance. As short focal length lenses are used at short distances, they exhibit distortion. In contrast, long focal length lenses exhibit compression.
  • Given a lens with focal length f1 and maximum f-stop number n1, used on a camera with a sensor having diagonal length of d1, if we want to take exactly the same picture with another camera with a sensor of diagonal d2, we must use a lens with focal length f2=f1*d2/d1, at aperture n2=n1*d2/d1
  • The film medium format look is hard to replicate with digital cameras because medium format film is physically bigger . Therefore, medium format film cameras have a shallower depth of field than digital cameras. For example, to replicate the Pentax 6x7 105mm f2.4 lens one would need to use an f1.1 lens in the full frame format. This lens is impossible to replicate using cropped sensor and micro four thirds cameras. It is also difficult to replicate it using digital medium format, as lenses with equivalent f-stops are not readily available.

What DSLR Photographers Really Want

I recently ran survey on Facebook asking Nikon D850 group members what they would like to see in the next iteration of this camera from Nikon. I don’t know what Nikon would call it, perhaps the D900. None of the items on the wish list will come to you as a surprise. Nikon, Canon, we hope you are reading this. Survey participants were given over 20 possible features to choose from.

So here is what we are asking for in order of importance:

1. Focusing system that combines phase detect with contrast detect: Phase detect auto focus (PDAF) is fast and gets the focus fairly close where it needs to be. Contrast detect auto focus (CDAF) is slow but when the camera is almost focused it can fine tune better than PDAF. Many mirrorless cameras incorporate both.

2. Eye AF: Definitely want our next DSLR to detect the eye and focus right on it. A lot of us own bright f1.4 lenses and want to nail focus on the eye wide open. We want this to work for our pets as well, and perhaps Safari animals, and maybe sharks too.

3. Even better low light performance and better dynamic range: Even though the D850 has the best low light performance  and dynamic range (DR) of any full frame camera, we realize that medium format digital cameras have an advantage. We want to close this gap. Therefore, we are asking for a 16 bit sensor and perhaps 14 stops of DR. We don’t really care for the megapixels, I mean 60+ MP would be nice but we are OK with our current near 50MP resolution.

4. In body camera stabilization (IBIS): All our mirrorless photographer frenemies have been throwing this one in our face, and we don’t have a line of defense here. We have heard rumors that the upcoming Nikon D6 will have IBIS and we want this on our next DSLR as well.

5. Hybrid view finder: Please don’t get us wrong. We love our optical viewfinder and it works better than an electronic view finder could in many situations. However, every now and then we would like to take advantage of features available in EVFs. One such feature would be focus magnification and fine tuning, another would be seeing the exposure histogram.

It should not be a surprise that focusing came out on top. The D850 has a high resolution sensor and if the focus is just slightly off it will show up when we magnify the image in Lightroom or CaptureOne. I think the current state of affairs is that we are forced to accept images with near perfect but not perfect focus. We want the camera to go that extra mile and get it exactly right with a high hit ratio. 

The Eye AF feature is obviously important to portrait photographers, although I did not think it would come at number two. However, in hindsight, it is clear that focusing right on the eye in portraits can be a challenge when shooting close to open or near wide open. Since I mostly use manual focus lenses, I am able to bracket my focus and get the focus just exactly right on the eye, however, with AF I have rarely been able to get my DSLR to nail it unless I stop down.

Improved DR and better low light performance is the most important for me personally, and I am pleased that it made the list coming in as number three. I really do care to see the detail in the shadows while not blowing out the highlights. I really have medium format envy and want to see 16bit raw files in full frame. I don’t want a medium format Hasselblad for $50K. Just give me 14 stops of DR in my DSLR.

IBIS is my second personal favorite and I am happy that fellow DSLR shooters agree. I think that high resolution sensors necessitate IBIS. I often feel like I need to shoot at 1/250 or above even with a 35mm lens or the results are substandard; and I shoot with the Nikon D810 which is only a 36MP camera. I think IBIS would allow me to shoot with LED lights more which I love. It is clearly important I do expect we will see almost all future DSLRs incorporating it.

Hybrid viewfinder came in at number five. But then again, I think that this is the enabling technology for features such as CDAF, Eye AF, and IBIS. I also want the magnifier feature for shooting manual focus.

I still shoot on the Nikon D810 and even though I love what I see in the D850 I did not feel like it was going to improve my photography much over what I could do with the D810. I am waiting for the features on the list and I want them in a DSLR. I don’t want a mirrorless because I just love the handling and form factor of a big DSLR. However, I eventually will switch to mirrorless if I can’t get these features in a DSLR.