{"id":15021,"date":"2018-10-12T05:16:15","date_gmt":"2018-10-12T04:16:15","guid":{"rendered":"https:\/\/phillipreeve.net\/blog\/?p=15021"},"modified":"2026-01-14T09:27:39","modified_gmt":"2026-01-14T08:27:39","slug":"carl-zeiss-c-sonnar-t-50mm-f1-5-zm-a-detailed-review","status":"publish","type":"post","link":"https:\/\/phillipreeve.net\/blog\/carl-zeiss-c-sonnar-t-50mm-f1-5-zm-a-detailed-review\/","title":{"rendered":"Carl Zeiss C-Sonnar T* 50mm f1.5 ZM: A Detailed Review"},"content":{"rendered":"

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We have become used to old lens formulas being revived and sold for occasionally huge sums of money to collectors and photographers hoping to create images with a magical vintage look. All of us here have been very sceptical about this. Mostly they have been simple lenses in simple bodies with poor technical qualities being sold for more than the price of the latest and greatest glass. From one perspective the legendary C-Sonnar from Zeiss is like this. It’s a classic design dating from 1932 whose principal design goal at the time was to reduce the number of air glass surfaces because the coatings of the day were so primitive. Why do we need it now? But Zeiss bought it back in 2006 in M mount as part of the ZM series. The optical design is not much changed, but it comes with modern coatings. Many prize it for magical rendering and flattering portraiture, others think it shows that not even Zeiss is above trying to rip off nostalgic hipsters. Read on and find out who is right!<\/p>\n

Specifications<\/h3>\n\n\n\n\n\n\n\n\n\n\n
Diameter<\/td>\n56 mm<\/td>\n<\/tr>\n
Length<\/td>\n45 mm<\/td>\n<\/tr>\n
Filter Thread<\/td>\n46 mm<\/td>\n<\/tr>\n
Weight (w\/o adapter)<\/td>\n250 g<\/td>\n<\/tr>\n
Max. Magnification (w\/o close focus adapter)<\/td>\n1:15<\/td>\n<\/tr>\n
Close Focusing Distance from the sensor (w\/o CFA)<\/td>\n0.9 m<\/td>\n<\/tr>\n
Number of aperture blades<\/td>\n10<\/td>\n<\/tr>\n
Elements\/ Groups<\/td>\n6\/4<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
The Carl Zeiss C-Sonnar T* 1.5\/50 can be purchased via our affiliate links at Amazon.com<\/a>\u00a0or else\u00a0B&H Photo Video<\/a>. You can get it new on eBay.com<\/a> here, or you can get it used on eBay.com<\/a> here.<\/address>\n
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Image Samples<\/h3>\n

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Build quality and handling<\/h3>\n

Like most ZM lenses it’s tight and precise, and as far as I know has only a little \u00a0copy-to-copy variation. It has a nice luxurious mechanical finish. I have a had my copy for a couple of years, and and is no blemish to the finish or optics. I believe some earlier copies had a tendency for the front structure to come loose, \u00a0but that seems to have been fixed.<\/p>\n

Focusing Ring<\/strong><\/h5>\n

It focuses from .9 metres to infinity in about 85 degrees, with a beautifully damped helicoid. The focusing ring is made of metal, and is ribbed in a way which makes it very easy to find and grip<\/p>\n

Aperture<\/strong><\/h5>\n

The aperture ring is a nice metal ring at the front of the lens, and stops down from f1.5 to f22 in 1\/3 stop increments, with a very precise click. There are also easy to see 1\/3 stop markings. The aperture ring is nicely ribbed.<\/p>\n

Hood<\/strong><\/h5>\n

The Zeiss hood is a very nice piece of metal which spring connects to the bayonet at the front. It is, however, absurdly expensive at over USD 100! If you have the silver model you can pick up an attractive satin screw-in vented hood that seems to match almost perfectly in both finish and aesthetics for about ten bucks on eBay.<\/p>\n

Adapting the lens to Sony<\/h5>\n

Normally I recommend the latest version of the Hawk’s Factory helicoid adapter for M lenses. But it’s best features\u2014adjustable infinity and the helicoid\u2014are of limited use on this lens. The helicoid is of less use because the quality of the lens drops off very quickly when mechanically focussed at \u00a0close distances (you are much better off using an achromatic diopter to get a little closer) The infinity adjust is less useful than usual because you are not likely to be using this lens for infinity purposes except in an emergency. I found a cheap satin chrome look helicoid adapter for very little on eBay. I wouldn’t use the helicoid regularly, but it’s there if I need it. But you might prefer a simple and solid M mount adapter like a Novoflex. \u00a0You can get one via our affiliate link at B&H<\/a><\/p>\n

Size and Weight<\/strong><\/h5>\n

This lens is tiny for a 1.5\/50. If you like the way it renders, and are prepared to take a bit of raw sharpness hit compared to modern designs, this is one of its great advantages. As far as I know it’s smaller and lighter than any fast 50 in production. So for those who love it’s distinctive look\u2014and I’m one at least some of the time\u2014it’s a joy to carry around and use, combining small size with precision feel. Here is a David and Goliath comparison with the Sony Zeiss FE \u00a0Planar 1.4\/50.<\/p>\n

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Optical performance<\/h1>\n

These results are based on use with a Sony Alpha A7rIII.<\/p>\n

Flare Resistance<\/strong><\/h5>\n

When the Zeiss Sonnar lens was originally designed, the main design goal was reducing flare by reducing the number of air-glass surfaces. The early Planar-Biotar type designs of the time were a little sharper, but suffered from very low contrast due to non image forming light. The Sonnar was much easier to use in backlight or other uncontrolled lighting.<\/p>\n

When the Sonnar was remade, Zeiss had the opportunity to put modern coatings on the C-Sonnar, which they did. In part because these coatings meant that air glass surfaces were less critical one pair of elements that were cemented in the original now have an air gap, giving somewhat better resolution.<\/p>\n

So is the flare performance of this classic, anti-flare lens designed equipped with modern coatings outstanding as you might expect?<\/p>\n

Not really. It’s very good; vastly better than an original Sonnar if you can find one in working order, or any of the Russian Sonnar copies. But modern computer design which traces non-image forming light is just as crucial as coatings, so there are more complex modern lenses that perform better against the light.<\/p>\n

For all that the performance is plenty good enough not to be a strike against buying one of these for its rendering.<\/p>\n

At wide apertures the sun in the frame lowers overall contrast quite a bit, but there are relatively few artefacts. The artefacts that there are tend to be a blob of discolouration off axis.<\/p>\n

Case 1: sun in midfield<\/em><\/p>\n