Cottage Tip: Densitometry Simplified

Densitometry and optical density seem to be a very abstract topic to too many photographers, but they're not. Optical density is in fact a very handy way to express the loss of light through a medium; in our case photographic film or paper. It is a valuable tool for image analysis.

Optical density is defined as:

OD = Log₁₀(Io / I), where Io is the non-attenuated light intensity (e.g. light reflection from blank paper base) and I is the attenuated light intensity (e.g. light reflection from an image area of the same paper)

In case when Io / I = 2 (the light intensity halves, i.e. is reduced by one stop), the density value equals to 0.30 which is a very handy number to deal with.

Very unfortunately, dedicated densitometers are quite expensive devices, even used ones. A new one can easily cost you about 1000 € or even more. If you're lucky, you can find a used one for a few 100 €. (And you still spend the same amount of money as for a SLR in good condition). Here I show an example how to make densitometric measurements of reflected light (i.e. from prints). Everyone who has ever dealt with alternative printing techniques has noticed the expression »image density«, be it for a cyanotype, platinum printing, and of course gum bichromate printing. Or any other technique. You can easily live without densitometry, but for getting consistent and predictable results in your printing, it is better to use it, especially in color or multi-layer printing. And you don't even need a densitometer. For densitometric measurements of acceptable precision, you need just a decent SLR or DSLR with spot metering capability-it is better to have a camera with 1/3 stop setting increments, but you can get along with a camera with 1/2 stop settings (like mine). For total (visual) densitometry, this is all you need. But for measuring the density of all three image-forming colors in color printing (yellow, magenta, cyan), you will also need a set of RGB filters. They need not to be the expensive optical quality filters-a set of RGB lighting filter gels (like Lee) are just right for the job, provided they faithfully represent the three primary colors (red, green, blue). You can buy a set of them online for a few €. I cut them in 75x75 mm squares and I hold them in front of the lens when I take the measurements.

The measurements were made with my Canon EOS 5, set in Av and spot mode. Aperture f/2.8 and ISO 100. Illuminated by window light.

Measuring is easy, just set your camera in aperture-priority mode at the aperture and ISO setting at your convenience, set the spot-metering mode, and place you print on an evenly illuminated surface. And you don't even need to have a focused image (actually it is better not to). First take the reading of the paper base (in secs) and then on the spot on the image you want to measure.

Say, you got these two readings for paper base and your spot of interest, 1/45 s and 1/15 s, respectively. Now you calculate the logarithm of their inverse values (actually their camera readings):

OD = Log₁₀(45 /15)= 0.48

This value tells you that the reflected light on that spot is attenuated by about 1.6 stop.

For the sake of illustration, I prepared a sheet of drawing paper (see above) with spots of different colors approximating the black and the complementary colors (yellow, magenta and cyan) differing in intensity (density). They are made with pastels and are by far not ideal, but they show the basic principle anyway.

When you want to measure the density of the yellow color, you measure it with the blue filter in front of the lens, since blue is complementary to yellow. For magenta, you use the green filter. And for cyan, the red filter. This is because you want to block the other two colors during your readings. Write down your readings and the calculate the logarithm values. These are the densities of selected image spots. Easy, isn't it?

Of course, these measurements are not super-precise, but they can help you a lot when you engage yourself in alternative printing.

The tools I used to measure the densities: my trusty SLR, and for YMC colors, the 3 Lee filter gels-red, green and blue. Pocket calculator not shown :)

Bad News:Lucky Film ceases Color Film Production

The Chinese Lucky Film Company was, and probably still is, the third largest film manufacturer. They became known outside China mostly because of their BW films, but they also (used to) have their line of color negative films. Now, with the decreased demand on film, they decided to shut down the color film production. The article can be found on the CCTV News site. With the uncertainty of Kodak's film line, there's only Fuji remaining in the color film market race for sure, for now. Probably we don't need to worry about BW films, they will be the last to go! But with color emulsions, it is a completely different story. There are many layers to be coated at the same time with great precision, and all the components must be more strictly "cooked"  and coated, otherwise unwanted color shifts may quickly occur etc....A film company thus needs much much of machiney and effort to produce a "workable" color emulsion compared to BW, but the sell price is just a bit higher.  Yes, the profit margins are thinner, but existent.

I dare to predict  a few things:
1. despite reduced production, demand for color film will stay quite stable
2. because of (1), the production (in numbers) of color film will stay more or less the same as it is now, but
3. the "purchase model" (at least) for color film will change: pre-production orders (and down-payments) will be made, thus ensuring the production/purchase quota to the manufacturer/photographer

Portfolio of the Week: Jens Taube

Dear Readers,

we still stay in the same country and this week we feature another photographer from Germany, Jens Taube. Interestingly, Jens' photographic journey has some similarities to Marc's path, the photographer we featured last week. The portfolio Jens sent us is quite compact and concise, as you can see. But nevertheless, it includes all the »substance« he aims for in his photographic endeavours. Jens is working primarily in medium format, with different Rollei cameras (SL66 and 6006), and in black and white. Besides the best technical combination in my view (6x6 and BW film), I was attracted by Jens' photos also because they have some particular kind of inherent emotional charge.

Here it is how he describes his path:

»Long before I started to photo-portray people, it fascinated me, how many different facets and how many different feelings a face can express. Or the gesture of a human hand. I took pictures I found in magazines or photo books as a drawing pattern as they gave me the chance to study frozen moments. Then in 2006 I exchange the drawing pencil for a DSLR. I wanted to create my own pictures instead of copying what others had seen and captured.

Two years later I made the step from the digital tool to classic black and white analogue photography.

Emotion is the subject that I focus on, more than on beauty and grace. Whenever I create pictures with someone, I encourage this person to listen carefully to their own insides. I show interest on which mood they encounter being at this particular place, in this particular hour. And that is the moment, when the face in front of my camera changes, when it convinces me to be honest and authentic, when it radiates another side of “beauty”. That is the moment that I long for when I portray.«

Jens described very well the very essence of his work and I think he succeeded very well in accomplishing his very own style. Bravo, maestro!

Jens' work can be found on Flickr and on his own website. Enjoy his work!

 Mitja 

All photos copyright: Jens Taube

Monday column; the another story... The learning process about digitalizing the first roll of developed film

Hello! I’m back again. It was busy for me lately, but here I’m. The last time I was talking about how I developed my first roll of b&w film. This story is about how a newbie digitalized his first roll of film.

I was describing in previous columns about how was my first contact with analogue photography. I quickly learned how to develop film on my own, but then I was left with developed roll of film with no clue what to do whit it. The enlarger and darkroom printing was for me still in clouds of, at that time, unknown future. At that time I have had no means of my own to view or scan the film, so the first move was that I went to the local quick lab, to scan my roll of film. Because unfortunately it was the nonstandard 120 format film, it could not be scanned on the fuji machine. But I was reassured that they could scan the film on the flatbed scanner. The result was disappointed for me. Not that I wanted or even that I could expect extreme quality from my first roll of film taken with Agfa Isola 1 and developed in the bathroom. 

 

I was not happy but I didn’t know any better. The next time I asked if they can scan the film in the best possible quality. I got this. 

 

Then I realized that the person who is scanning my film has no clue how to scan a film on a flatbed scanner. And for the results I was getting it was very expensive. I quickly made a calculation that a scanner will pay off in scanning only 20 of 120 format films.

After my first encounter with analogue photography I was beginning to shoot with cameras with more “standard” film format. This was scanned on the Fuji frontier scanner, and the workflow for doing that seemed that was more straightforward at that minilab. The results were better. 

 

But none the less, I made the decision to buy a flatbed scanner. I scanned again the disappointingly scanned film. The result speaks from themselves.

Matjaž

Cameras of Yesteryear: Yashica Dental Eye

What a funny name for a camera? Well, not really. In fact, its name says it all: the camera was primarily targeted to dentists but also to pathologists, forensics etc. who needed to do photo documentation of their work, patients and so on. More specifically, macro photographic documentation. A very peculiar, niche camera.  Being a specialistic camera, so it was its price-comparable or higher than a Contax SLR. There were three generations of this camera; the first one with a 55 mm lens, the other two with a 100 mm lens. The camera features a fixed macro lens with a built-in ring flash and capable of reproduction ratios between 1/10 and 1/1 (2/1 with additional diopter lens). The focusing ring doesn't tell you the distance, only the reproduction ratio. Almost everything is automatic, which is not necessarily a bad thing, as it turned out from my first tests: you can only select whether you activate the flash or use ambient light only (you can also set flash under/overexposure by 1 stop). But there is no flash TTL metering. Instead, it has a simple yet brilliant solution-the flash output remains constant while the aperture gets smaller as the reproduction ratio gets higher. Two problems are solved this way (may be even three, considering the high reflectance of teeth): the photos are always correctly exposed, regardless of shooting distance, and the compensation of the diminishing depth of field. Genial, isn't it?

Yashica Dental Eye II

I acquired this camera from Ebay for a very low sum (compared to the very cheapest pocket digicams), hoping to get it to use for macro work-not for me, but for a very special person, very fond of macro photography.  I must admit, I had no expectations at all regarding optical quality, but considering  the sell price...well, I could live with it. Nonetheless, this camera became very fashionable among lomographers, due to its ring flash (but lomographers cannot be defined as picky regarding lens quality...). Oh, how happy I was to be proven wrong: the lens' performance is simply outstanding-comparable to a Zeiss glass in terms of sharpness; however, the lens yields quite a  »hard« image, typical of most macro lenses. One of the amazing features of this camera is certainly its focusing screen-even though the lens is »only« f/4, I have never seen such a bright screen, not even in a Rollei. Even a half-blind person would be ableto focus, I am pretty sure. Simply put, you can get (almost) all you need for macro work in one piece on equipment, with no extra gear. And fortunately, the camera comes also with a synchro socket, for those who need and additional flash (e.g. for background illumination). For those (like me) who don't mind (or even prefer) to shoot on film, I can only say: go for it. It will cost you only a fraction of a macro lens (new or even used one) and it will deliver outstanding results and amaze you with ots ease of use and simplicity. Provided you find one.

 

Not only for macro, the camera is useful also for other closeup shots.

This shot probably best shows lens' clinical sharpness (pun intended).

A macro handheld shot. A tripod would help in having sharpness in the right spot. All shots made on Kodak Ektar.

Portfolio of the Week: Marc von Martial

Dear Readers,

This week we feature another German photographer from Bonn, Marc von Martial. Marc is a freelance graphic designer by profession. He, as many others, started with digital equipment (not counting the snapshots from the film era), but got »infected« soon with analog, starting with lomography, when he fell in love with the images made with a Holga. Now, he primarily shoots on film, and he also develops all the films by himself. He likes to experiment with film very much, including expired film. His main focus is on people/portrait photography, some landscape, and also some street photography. He is working on a few photographic series, developing them over time. He describes himself  mainly as a medium-format-and-polaroid kind of guy, since he mostly uses his beloved Pentacon Six TL, with the CZJ 80/2.8 and 180/2.8 lenses (the same lenses he uses also on his DSLR, by his own words better lenses than Canon L series lenses!) and the Polaroid Land 350 and SX-70 Alpha cameras. He also makes great use of various Holgas, yet he also has other cameras in his arsenal, among them a Hasselblad 500CM, various 35mm cameras, and some other plasti/toy cameras. Please, take also a look at his bio just below his photos. I think Marc makes a very good argumented description why film rules for him, even though he is tech junkie otherwise. Marc's work can be found on Flickr, Marc's blog and his webpage. Enjoy his work!

Silver regards

Mitja

 All photos copyright: Marc von Martial

Marc's Bio

Since a year I focus on people and portrait photography, something that really satisfies me. I enjoy communicating with my models to develop ideas and make them feel to be part of the process. Many of my sessions go a very spontaneous route. I never try to force my models in a certain direction. If I feel they get bored or uncomfortable or it simply does not work, then I do not push it, I take my time. I think that’s an important part of getting believable portrait. The slower way of taking photos with film also helps to set a more relaxed mood. Many of my models did not take part in analog sessions before and I often hear how much they like the slower flow and that it is not necessary to take hundreds of photos to get that “one” great shot you aim for. Of course I understand that for commercial jobs this does not always work, although my approach helped me a lot in the past getting jobs done in a very satisfying way. I love to play with available light and this is also why I love film. Film “feels” light. It embraces and touches it. Combine that with a large format print on the wall and you know why you are in love with film photography. Photos need to be printed, even if you put them in a box after that. Nothing beats holding a print in your hands. And no, I’m not anti iPad/iPhone or digital, I’m a tech nerd actually.

I take my inspiration from the large Flickr community, photo books and blogs I read. I adore the photography of Rüdiger Beckmann, Jan Scholz, Hengki Koentjoro, Jochen Abitz, Jan Bishop, Magda Andrzejewska and the artistic perfection of Vernon Trent. There’s many more and I did not mention masters of the past on purpose. I have to say though  that the “analog” friends I made in the last two years influence and inspire me a lot too, not always through their photography but trough the mix of styles they bring together. Thanks guys!

My plans for the future are getting into large format photography now, I recently acquired a Graflex Speed Graphic, starting “small” 4x5 and combine art and photography way more with some alternative print and development processes. I guess that is also the graphic artist and that unstoppable curiosity in me that wants to do this :) We will see, maybe a small exhibition too, for now I’m super flattened by all the positive feedback I got this year.

Marc von Martial