Harking back to Kodachrome

My father took most of my childhood photos (like these) on Kodachrome slide film. Kodachrome was the only color game in town for a long time, but was eventually superseded in the marketplace by C41 color print films and finer grained E6 slide film.

Kodachrome has a distinctive sharpness (acutance, not resolution), and excellent durability when stored in the dark. Many photographers still shoot Kodachrome for its special “look”, even though processing options are diminishing and Kodak jacked up the price. Kodak recently announced it is closing its Fair Lawn, NJ processing lab, the last Kodak-owned plant in the US for Kodachrome, and there are now only three labs left worldwide that can run the complicated process (Dwayne’s in Kansas, Kodak in Lausanne, Switzerland, and a lab in Japan). Kodachrome was actually discontinued for a while, and brought back after strident protests, but the writing is on the wall.

Projectors and light tables

Every now and then, we would dust off the slide projector and have a slide show. I even remember building a surprisingly effective slide projector when I was 9 using Legos, a flashlight and a jar of peanut butter filled with water as the lens. Slide projectors are hard to find, a pain to setup and most people groan instinctively when one comes up, associated as they are with dreary slide show of other people’s vacation pictures. The LCD computer monitor is the successor to the projector, and many people no longer have prints made at all, perhaps because they subconsciously realize that the 500:1 contrast ratio of a LCD monitor yields significantly livelier images than prints can achieve.

light table and loupes

A light table is just what the name implies – a piece of frosted plastic illuminated by daylight-balanced fluorescent tubes. Basic models like my Porta-trace shown above are inexpensive. Loupes, on the other hand, are a different story.

Loupe basics

Loupes (French for “magnifying glass”) are high-quality magnifiers, originally used to help focus images on a ground glass, and later to view slides or negatives on a light table. You can find them in all shapes and sizes, at prices from $15 for a cheap plastic model, all the way to over $300 for a Zeiss loupe for viewing 6×6 medium format slides. Slides viewed on a light table with a high-quality loupe are a treat for the eyes, because of the high contrast (1000:1) that you cannot get with prints (more like 100:1).

There are two ways you can use a loupe: use a high-power (10x or higher) to check slides or negatives for critical focus), or a medium-power loupe to evaluate an entire frame (usually 5x-6x for 35mm, 3x-3.5x for medium format). Viewing an entire frame is more challenging than just checking for focus in the center, because the loupe must provide excellent optical quality across the entire field of view. There are variable magnification (zoom) loupes available, but their optical quality is far below that of fixed magnification loupes, and they should be avoided for critical examination of slides or negatives.

I have accumulated quite a few loupes over time. The most famous brand in loupes is Schneider-Kreuznach, a German company noted for its enlarger, medium format and large format lenses. Many other brands make high-quality loupes, including Rodenstock, Pentax, Nikon, Canon, NPC, Leica and Zeiss. I do not live in New York, and have thus not had the opportunity to compare them side by side at a place like B&H Photo, so I pretty much had to take a leap of faith based on recommendations on the Internet at sites like Photo.net.

Peak

The Peak was my first loupe. Dirt cheap, and reasonably good for the price, but that’s pretty much all it has going for it (more on that below).

Zeiss

I was put off by reports on the plastic construction of the new line of Schneider loupes, and opted for a Zeiss loupe instead, based on the reputation of Zeiss lenses (my first camera was a Zeiss, and I also have a Zeiss lens on my Hasselblad).

The Zeiss Triotar 5x loupe (the box does not mention Contax, but as it is made in Japan, it is presumably made in the same factory) comes in a cardboard box that can be turned into a protective case by cutting off the tabs on both ends. It does not include a carrying pouch or protective box, which is regrettable, specially for a product as expensive ($160), but apparently most high-end loupe manufacturers do not bother to include one. It does not include a neck strap either, which could be more of an issue for some. How can you look like a glamorous New York art director without a loupe around your neck? More seriously, the strap is particularly useful if you are going to use the loupe for focusing medium or large format cameras against a ground screen.

The loupe is shipped with two acrylic bases that screw into the loupe’s base. One is frosted, and is used as a magnifier to view prints or other objects, with ambient light filtering through the base to illuminate the object. The black base is used to shield out extraneous light when concentrating on a slide or negative on a light table or a ground glass. Some loupes have a design with a clear base and a removable metal light shield. Which design you prefer is mostly a matter of personal taste. The loupe has a pleasant heft to it, and impeccable build quality. The main body of the loupe itself is solidly built of black anodized metal, with a knurled rubber focusing ring.

The optical quality is what you would expect form Zeiss. Crystal clear, sharp across the field of view, and no trace of chromatic aberration in the corners. You can easily view an entire 35mm frame and then some, although I suspect eyeglass wearers might find the eye relief a little bit short.

Edmunds pocket microscope

The Edmunds direct view microscope is a versatile instrument, available in many magnifications, with or without an acrylic base (highly recommended) and with or without a measurement reticle (metric or imperial). Due to the high magnification, the image has a very narrow field of view (only 3mm), and is quite dim. Unlike the others, the image is reversed, which requires some adaptation time. The level of detail you can observe on slides taken with a good film like Fuji Provia 100F, using a good lens and a tripod, is absolutely stunning. This is a rather specialized instrument, but well worth having in your toolkit.

Rodenstock

The Rodenstock 3x 6×6 aspheric loupe has a list price of $350 and usually retails for $250. Calumet Photo sells the exact same loupe under their own brand for a mere $149 (I actually got mine for $109 during a promotion), which is not that much more than a cheap (in more ways than price) Russian-made Horizon.

There are naturally fewer loupes available to view medium format slides or negatives than for 35mm. Schneider, Mamiya/Cabin, Contax/Zeiss and Rodenstock make high-grade loupes for this demanding market. If you have a “chimney” viewfinder on your MF camera, you can actually use that as a loupe.

Rodenstock is famous for its large-format and enlarging lenses, and this loupe is very highly rated. The construction is plastic, but still well-balanced and not too top-heavy. It does not carry the feel of opulence that the Zeiss has, or even the very nicely designed Mamiya/Cabin loupes (more on that below), but is still clearly a professional instrument. It has a two-element aspherical design for sharpness across the entire field of view, and coated optics. It comes with a red neck cord, and the base has a removable plastic skirt that slides in place and can be reversed between its clear and dark positions. The eyepiece has a rubber eyecup and a knurled rubber grip for the focusing ring.

I compared it side by side at Calumet San Francisco with the Cabin 3.5x loupe for 6×4.5 or 6×6. The Cabin had a solid metal constuction (somewhat top-heavy), but its screw-in skirts are less convenient than the slide-in one used in the Rodenstock, and the image circle is too tight for my Hasselblad 6×6 slides. I think that loupe was really designed for 645 format and opportunistically marketed for 6×6, when the 6×7 loupe would actually be more appropriate for that usage. The optical quality is very similar and both are excellent loupes. I did not try the Mamiya/Cabin 6×7, unfortunately, as it was not available in the store, but in any case the Rodenstock was a steal.

The optics are excellent, as could be expected, with crisp resolution all the way into the corners and no trace of chromatic aberrations. There is a smidgen of pincushion distortion, however, but not enough to be objectionable (I took the slightly convex curved square skirt out to make sure this was not just an optical illusion).

One thing to watch out for: even though the optics are coated, they are very wide and you have to be careful to keep your eye flush with the eyecup to obscure any overhead light sources like lightbulbs or fluorescent panels and avoid seeing their reflections in the loupe’s glass.

The most comprehensive resource for medium format loupes on the Web is Robert Monaghan’s page on the subject.

Edmunds Hastings triplet

This isn’t really a competitor to the other loupes, as it has a very narrow field of view of only 10mm in diameter. It is also tiny, and I carry mine in my gadget bag. It has a folding jeweler’s loupe design with a folding metallic shield to protect it. Optical quality is of the highest order.

Schneider 10x

Despite its plastic construction, this loupe exudes quality. Unfortunately, the strap is really flimsy – the rubber cord is merely glued into the metal clip, and will easily pull out. I glued mine back, and crimped it with needle-nose pliers for good measure, but I don’t know how robust this arrangement will be.

The optics are excellent, without any trace of chromatic aberration. The usable field of view is surprisingly wide for a loupe with this magnifying power, although your eye has to be perfectly positioned to see it. I estimate the FOV diameter at 20mm, as you can almost see the full height of a 35mm mounted slide. I have an Edmund Optics magnifier resolution chart (it came with the Hastings triplet), and the Schneider outresolves it across the field of view . This means the Schneider exceeds 114 line pairs per millimeter across the frame, quite remarkable performance.

The importance of a good loupe

Golden Gate cable detailFor a real-world test, I took my 6×17 format Velvia 100F slides of the Golden Gate Bridge, and looked at the suspension cables. The picture to the left shows the details I was looking at (but the fuzzy 1200dpi scan on an Epson 3170 does not remotely do justice to the original). Each bundle of 4 cables (4 line pairs) takes 0.04mm on the slide (I used the 50x Edmunds inspection microscope to measure this), hence you need 100lp/mm to resolve it. The Schneider 10x, Edmunds 10x and Zeiss 5x loupes all resolve the four cables clearly. My old el cheapo Peak 10x loupe did not, nor the Epson scanner, which led me until recently to believe my slides were slightly blurry because I had forgotten my cable release that day. So much for the theory you do not need an expensive 10x loupe to assess critical focus because only the center counts…

Update (2012-02-10):

In 2007 I added a Calumet-branded 4x Rodenstock aspheric loupe to my collection. Unfortunately, it is now only available under the original brand, for 2.5x the price I paid for the rebranded one, but you may luck out and find old-new stock at you local Calumet Photo store. The market for loupes has mostly evaporated, along with the popularity of film, and choices today are pretty much limited to Schneider and Rodenstock.

The Rodenstock 4x loupe has one great ergonomic feature: instead of interchangeable clear and dark screw-in skirts, it has a clear skirt and a sliding dark outer skirt. This allows you to switch very quickly from inspecting prints to slides, without the laborious swap the Schneider or Zeiss force you into. Optically it is excellent, sharp across the field and with only a smidgen of pincushion distortion. I have not tried the 4x Schneider loupe, which gets rave reviews, and cannot comment on whether the ergonomic improvement in the Rodenstock warrants a 50% premium in street price over the Schneider.

One loupe I cannot recommend, on the other hand, is the Leica 4x magnifier. It has severe distortion across the field, which is ridiculously limited at 3 or 4mm, and optical quality is worse than a cheapo plastic loupe from Peak.

Update (2012-02-25):

I added a Schneider 4x loupe to my collection. Build quality and strap is similar to their 10x loupe. It is sharp across the entire frame, with only a smidgen of pincushion distortion. It is also noticeably brighter than the Zeiss Triotar or the Rodenstock 4x, and has more contrast as well. The contrast makes it seem superficially sharper than the Zeiss or Rodenstock, but examination of the Edmunds test chart shows all three loupes outresolve the chart.

I think this will be my new favorite loupe for 35mm use.