REVIEWS - Canon 100mm F2 Serenar LTM / M39

OVERVIEW

Canon's S-mount rangefinder production started in 1933 and ended in 1968. The S-Mount is a Leica M39 screw mount and is focus coupled - meaning the lenses will work on a Leica M rangefinder via a standard M39 to Leica M adapter. The Canon lenses are often referred to as LTM mounts; LTM means Leica Thread Mount.

The Canon 100mm F2 Serenar was introduced in 1959. In 1959 the 100mm F2 Serenar's MSRP price was 33,000 Yen, or ~$91 in US dollars. In today's dollars the price would be $1000-$1200 after adjusting for inflation, etc. Three versions were produced and the changes were only cosmetic (the front ring and front lens cap). Canon continued to evolve the 100mm Serenar's optical design for Canon's early SLR lenses in the 60's and early 70's.

BUILD QUALITY

As one would expect from a 1960's vintage lens, the lens is metal, with more metal and some added metal for extra measure. Add a black lacquer piano finish with some matte finish silver bits, and it is classy looking as lenses go. The lens is solid with no wobble or play, manual focus is smooth and the aperture ring clicks decisively from stop-to-stop in whole stop increments. Being a screw mount lens, a M39 to Leica M-mount adapter is needed; I opted for a Voigtlander 28/90.

The front lens cap is the press-on type. A separate lens hood slips over the lens barrel and a small thumb screw holds the lens hood in place, pressing a ring against the lens barrel. Lenses with a red "EP" in a red diamond marking on the front retaining ring indicate that the lens was sold at a military exchange post, supposedly this makes the lens more collectible. There is some debate as to what the EP actually standards for, perhaps Exchange Post or Exchange Program. There is no doubt that the lenses were sold at US military PX/BX stores.

OPTICAL DESIGN

Jiro Mukai is credited for the 100mm F2 Serenar's design (along with several other Canon lenses). His work was based in part on earlier designs from Hiroshi Ito, who refined Canon's gaussian optical design for use with faster apertures (reducing aberrations).

Diagram from Canon's U.S. Patent 2681594, Issued June 1954

It is unknown (to me) if the above graphic is for the Canon 100mm F2 Serenar or one of the other 85mm Serenars. The 85mm F1.9 came first, then the 85mm F2 and 100mm F2 and the 85mm F1.8 was the last one. Hiroshi Itoh designed the earlier lenses - 85mm f/1.5, 85mm f/1.9 and 100mm f/3.5; and Jirou Mukai followed up with the 85mm f/1.8 and 100mm f/2 (source: mflenses.com). Here is a list of Canon rangefinder lenses by designer:

Source: RangefinderForum Post

It is interesting to note that the 85mm F2 Serenar was designed by Mr. Kuroki. The 85mm F2 and 100mm F2 are often cited as being similar optical designs, so it reasonable to assume they were designed by the same person, but they were not. AntiqueCameras.com lists the Canon LTM lenses with their market introduction date, a short comment about performance and their recent used prices. Frank Mechelhoff also provides some interesting Canon LTM history as well, click here.

The 100mm F2 Serenar is a double gauss design, commonly referred to today as a Planar™ design. The Zeiss Planar's date back to 1896 with the first symmetric lens design by Dr. Paul Rudolph. Subsequent Planars retain their doublets, though they typically are not 100% symmetric (see Wikipedia for more info). The 100mm Serenar was produced using Canon's new Super Spectral Coatings (S.S.C.) multi-coatings. The 100mm Serenar's front element is coated, and most likely there are some single coatings on the internal elements as well to improve light transmission. Uncoated lens elements lose ~12% of their light; whereas a coated element blocks less than 1% (assuming modern-day coatings).

HANDLING

The Canon 100mm F2 Serenar is a large lens by rangefinder standards. Mine weighs 501 grams including the Voigtlander adapter. For all intents and purposes, the 100mm Serenar and Leica 90mm F2 Summicron-M APO weigh the same, though the 100mm is about a 1/2 inch longer. Compared to the Leica 90mm F2 Summicron-M APO, the Canon 100mm Serenar does feel slightly nose heavy. With large lenses such as the 100mm Serenar, the Thumbs Up grip accessory helps significantly.

The Canon 100mm Serenar was produced before the days of double helicoids, so when focusing, the aperture ring rotates with the outer barrel. Another sort of "back then" feature was canting the lens ~30˚ towards the viewfinder. Supposedly this allows the photographer to see the focus distance scale via the viewfinder. In use it makes no difference, but seeing an off-center lens is a bit odd (in my opinion).

Like the Nikon 105mm F2.5 P.C. (also made in a M39 LTM mount), the focus ring seemingly turns forever. Racking focus is ~315˚ of rotation. With Live View on the Leica M, the long focus throw is helpful with fine tuning focus. And with the very nicely dampened focus ring feel, manual focus is a joy.

Composing with a 100mm lens on a Leica M can be tricky if wanting to be exact with the 90mm frame lines. If shooting via the rangefinder window, I use the 90mm frame lines, shoot alittle loose and crop as needed in post. Exact framing requires an EVF or Live View, and frankly nowadays, this is the way to go. With a Leica M11-P and a Leica Visoflex 2 Electronic Viewfinder, framing and focusing are worlds easier. The same holds true if using a Leica SL3, Sony A7RV or similar.

PERFORMANCE

Even 60 years after its introduction, the Canon 100mm F2 Serenar is still a sought after lens for good reason:

Sharpness - The Canon 100mm Serenar is surprisingly sharp both wide-open and stopped down. I have been amazed at how sharp and detailed these mid-century lenses can be. Even at F2 the 100mm Serenar can compete head-to-head with a modern lens.

Contrast - Lenses from this era are often characterized as having less contrast. The blacks are not as deep, but the mid-tones have more tonality and nuance. There can be some nice micro-contrast in the bokeh. The 100mm F2 Serenar has an amazingly ability to compress dynamic range. It is common for the histogram in Capture One to look like:

Histogram from Phase One's Capture One

Note the additional headroom in the highlight range and that the histogram trails off towards the deep blacks. On one hand the lens is very capable of containing / retaining highlights. On the other hand, the images can look flat and need post processing for some "pop".

Bokeh - The picture below compares the wide open bokeh from the Canon 100mm Serenar to the Leica 90mm F2 Summicron-M APO. At first the pictures seem similar, but if looking closer, the Canon 100mm LTM is more abstracted, especially in the image on the right.

Canon 100mm Serenar Bokeh vs Leica 90mm Summicron-M APO

The lower contrast and added 10mm in reach result in a slightly gentler bokeh. The bokeh has more gaussian blur and is more diffused than a Leica M ASPH lens. The added 10mm of reach (compared to a 90mm lens) goes a long way towards smoothing the bokeh as well. If anything gives the 100mm Serenar a "fingerprint", it is the lens' blend of bokeh and contrast. The images are more subdued than those from Leica 90mm F2 Summicron-M APO.

Aberrations, Flare and Distortion - At F2 there can be some purple color fringing in high contrast areas:

Chromatic Aberrations - Click Image to Enlarge

Sensor bloom could be compounding the issue. The purple CA is easily removed in Capture One or Lightroom. And like most lenses, the CA goes away when the lens is stopped down. As for flare, the 100mm F2 Serenar will flare if shot into the sun. The effect ranges from crappy to awesomeness. Also, I have also seen the light bounce off the sensor and reflect back off the aperture blades (aperture was at F22) and ghosts of the aperture blades became part of the image:

Aperture Blade Reflections - Click Image to Enlarge

This anomaly is most likely due to no (or inferior) lens coatings on internal element(s) - lens multi-coatings were in their infancy in the 1950-1960's. With 1000's of pictures taken, I have seen this happen in this one shot. Having shot many cityscapes in Dallas and Seattle, I would say the 100mm Serenar is effectively distortion free. Nor, have I noticed any focus shift or curvature of field.

If shot into or in the general direction of the sun (or any other bright light source), the 100mm Serenar is likely to flare. If not wanting flare, I would probably choose the Leica 90mm APO for those types of harsher shooting conditions. Though, lenses like the Leica 90mm F2 Summicron-M APO and Leica 75mm F2 Summicron-M APO are also prone to flare or veiling.

3D Effect - Netting a 3D effect depends heavily on lighting, and given the right conditions the Canon 100mm F2 Serenar has a 3D look or feel occasionally.

CONCLUSION

Canon 100mm F2 Serenars typically sell for $400 to $800. That buys a sharp lens with nice bokeh and a bit of a retro-look character in how the lens renders. The Canon 100mm has some quirks with its flare and handling, so for me the lens is a nice addition to my existing Leica M ASPH / APO lenses. If wanting add some character to your Leica M lens line up, the Canon 100mm is a bargain.