Silverbased

Projects and ponderings for film photographers

120 Film: Some History

January 10th, 2010 by Vox in Vintage Camera | No Comments →

A friend tipped me off to a great archive of magazine advertising with a collection of historical photography ads—going all the way back to the original 1888 Kodak.

Of special interest is a 1901 ad for the Kodak No. 2 Brownie (see a larger version from the source). As many know (and as I’ve written about before), Kodak launched an entirely new roll size for this camera, called 120—the same 120 film we’re still using today.

Kodak Brownie No. 2 Ad, 1901

Kodak Brownie No. 2 ad, 1901 “Youth’s Companion” magazine

The No. 2 Brownie took 2-1/4 x 3-1/4 inch photos (aka 6×9 cm). But it’s interesting that the film length was originally shorter: Only 6 shots (today’s 120 would give 8).

Kodak had introduced an earlier Brownie using film size 117, at the startlingly low price of $1—making an all-out effort to sell cameras simple and cheap enough for children. So it’s not an accident that this ad uses an image of the curious little girl and her schoolbooks. (But what is the deal with that hat?!?)

The name “Brownie” and that scary figurine appearing on the table refer to a series of children’s illustrations drawn by Palmer Cox, very popular with children of the era. It’s not clear whether Kodak actually licensed any drawings from Cox, or merely created their own elf-like Brownie illustrations (which to be fair, had originated from Scottish folklore).

I have always wondered if the Brownie name was also a tip of the hat to Kodak’s original camera design wizard, Frank Brownell.

Compared to the original Brownie, the No. 2 took larger photos and, significantly, included a viewfinder! Two, actually—allowing you to frame photos horizontally or vertically. This helped justify the doubled, $2 price tag. With this addition, the No. 2 became the template for thousands of cheap box cameras to follow—both from Kodak, and its competitors, like Ansco.

Eventually the 120 size was taken up by other, top-quality cameras: First the Rolleiflex and later the Hasselblad. Both of these helped cement the reputation of 120 as a “serious camera” film.

But the association between 120 and Brownies remained, enough so that in Japan, many kept referring to the size as “Brownie film.” And in 1958, this inspired a name for Zenzaburo Yoshino’s innovative new 120 camera—called the Bronica.

Let’s hope 120 film survives somehow until at least the year 2021—in time to celebrate its 120th birthday.

Aspheric Lenses, And Why You Should Care

December 17th, 2009 by Vox in Optics, Mechanics, Electronics | No Comments →

Imagine taking two disks of glass and rubbing them together, along with a slurry of abrasive grit. As glass is ground away, what happens next? If the grinding motion is completely even, both surfaces remain flat. But with even a slight change in pressure, the grinding surfaces begin to take on a curve.

A moment of thought should convince you that the curve must be a section of a sphere. That’s the only shape where the two surfaces will always stay in contact as they move. Any high points that deviate from a sphere would eventually be ground away.

This is the reason why a spherical surface is the easiest (and least expensive) curve to manufacture glass lenses to.

This insight is well understood by many old-school amateur astronomers, the ones who go through the long process of grinding their own telescope mirrors. But there’s a problem: the figure actually required for a telescope mirror is not a section of a sphere—it’s actually a parabola.

Although the difference between the two is infinitesimal, the telescope-builder needs to hand-polish subsections of the mirror to reach the right final shape. And the polishing and testing to reach this special curve accounts for a large fraction of the total labor required. The effort turns the optical surface into an aspherical one—simply meaning, any curve that deviates from a simple sphere.

Camera lenses are made using multiple glass elements (at least three are needed for a reasonably aberration-free image). Those surfaces are typically all spherical. But an “aspheric” camera lens includes one of these specially-polished aspheric surfaces (or in rare cases, a couple of them).

Why Aspherical?

But since aspherical surfaces are harder to manufacture, they cost more. So why use them?

Aspherical Lens Example

A recent aspherical lens

There’s a misconception, often repeated in internet discussions, that aspherical surfaces are needed to “correct spherical aberration.” This statement is very misleading.

We should back up and explain that spherical aberration is when light rays passing through the edge of a lens focus at a different distance than ones from the center. This is mostly undesirable, because then the fine details of your photo subject will lack contrast. (We should note, however, that a bit of uncorrected spherical aberration can improve a lens’s bokeh.) Spherical aberration is particularly hard to cure at fast f/ratios, since the ray paths must bend so steeply at the edges of the lens.

A lens designer needs to balance many factors when creating a new product. There are multiple aberrations to correct, across the whole image, including spherical aberration. But there are also issues of weight, size, and manufacturing cost to consider.

It’s easier to design a good lens when you have more “degrees of freedom.” The more different glass types you can add, and the more surface curvatures you can tweak, the more flexibility you have to cancel out aberrations.

So if a lens design has enough complexity, it can give perfect correction of spherical aberration—even using only spherical surfaces. But it may prove impractically large and expensive to manufacture.

What aspheric surfaces offer is simple: More degrees of freedom.

An aspherical surface can improve a lens design without adding extra glass. Computer ray-tracing can adjust the curvature across an element’s width, reducing all aberrations (spherical being just one). If an aspherically-polished surface can replace three or five spherical ones, it can justify its cost—yielding a smaller, lighter lens that may be be less prone to flare.

Compact Voigtländer Ultron 35mm f/1.7

Long ago, aspheric lenses were pretty exotic: Polishing the special shapes required lots of extra labor. However technology has moved on, and now there are automated processes that can produce good-quality non-spherical surfaces. As a result, aspheric optics have gone mainstream.

A compact 35mm f/1.7 lens with one aspheric surface

So aspheric lenses aren’t made from some crazy unobtanium, and they don’t have magical powers. They’re just a way to build a better lens using fewer elements, and that’s all.

Polaroid: The Last Call

December 18th, 2008 by Vox in Photo Zeitgeist, Polaroid | No Comments →

As I’ve mentioned for many months, the end is near for Polaroid instant films. The company announced in February that all production was stopping; and the Enschede, Netherlands factory ceased operations on June 6th, 2008. (Although ironically, CNN only just discovered this story last week.)

All the factory equipment was subsequently auctioned off and scattered to the four winds—seemingly spelling doom for Polaroid integral films (meaning the most popular, squarish 600 format; and the rectangular Spectra/Image type).

Polaroid 600 Integral Film

Why is the Polaroid lady twisting her own head off her body?

Fujifilm continues to produce “peel-apart” instant films which are compatible with some Polaroid cameras and backs. Ironically this means certain 1960s Polaroid cameras will remain usable longer than the ubiquitous recent Polaroid OneStep and One600 models. (The 1960s cameras do require a weird-sized battery, however.)

Fuji also makes its own line of integral instant films called “Instax.” However Instax technology is completely different from Polaroid’s, and none of those films are compatible with any Polaroid camera.

To re-create Polaroid’s 600 film from scratch would be a complex and costly process (remember that each pack also contains a special flat battery). It’s doubtful Fujifilm would have a motive to take on that challenge, when they already makes a competing product. There are not many other players in the market with the technical expertise to revive integral film; so unless some mystery savior appears, we should assume 600 and Spectra are disappearing for good.

Earlier this year, the best deal I could find on 600 film was from OfficeDepot’s online store. However for many weeks there has been no more stock available to my Zip code; and anecdotally that seems to be true for other regions of the US too.

So this week I stopped off at a local Target store—in my area, this is the last bricks-and-mortar retailer with decent quantities of 600 remaining. I got two serious shocks: First, the price had been raised to US $17 a pack (yes, that’s $1.70 per photo); and second, the expiration date on the packs was “09/09.”

Polaroid Expiration Date Code

09/09 is the mark of the End Times

Why is that date significant? A group of Dutch Flickr members toured the Enschede factory in May, two weeks before it shut down; and the date code they saw on finished packs was 09/09. Note that this is actually later than the “Aug 09″ final expiration date listed in Polaroid’s own phase-out announcement.

Apparently there may have been one final week’s production stamped with the expiration date “10/09.” Packs with that date are now available at the European “PolaPremium” website.

This new operation has made a splash selling small batches of various unusual Polaroid films, produced in the factory’s final days. (Some have questioned whether these special products were simply a way to use up old or substandard chemistry. I have no firsthand experience with these films; and considering the shipping charges to the USA, I don’t plan to try them.)

In any case, the message to Polaroid fans is clear. If you see packs with the date code 09/09, assume it’s your last chance to buy them. Ever.

(Well okay. I’m sure gouging profiteers on eBay will have packs to sell for the next few years—but at grossly inflated prices.)

So look deep within your soul (and your bank balance), and decide what it’s worth to you, to save a few final packs for special occasions.

Remember that the life of Polaroid films can be extended a few years past their expiration date by keeping them in the fridge. (Don’t put them in the freezer, because you can wreck the vital developer goo pods which form the image.)

Expired Polaroid film can lend interesting quirks to an image, due to color shifts and fading; or the image can be streaked or incompletely developed. But once film packs are many years out of date, they begin to fail entirely. Batteries die, or the developer pods dry out.

So don’t go hoarding more film than you would shoot in the next 2-3 years. You would just be taking precious shots away from another Polaroid-lover, who might be able to use it.

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Update 19 Dec. 2008: Just as I posted this, the Polaroid corporation announced it was filing for Chapter 11 bankruptcy. The reasons have little to do with instant photography; but the company’s troubles make the future of the Polaroid brand even murkier.

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Update February 2009: Yes, I have heard the excited talk about The Impossible Project to restart integral film production. It turns out some of the essential factory equipment was saved after all. I will be curious to see how it pans out. Here’s a good podcast radio interview with the technical head of the project.

Remember, they have numerous engineering hurdles to overcome before any film reaches shelves; once it does, it’s likely to be “quirky” emulsions at high prices.

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