Zeiss Planar T* 2/50 ZM

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Last updated September 26, 2012

The Zeiss description for this lens

The Perspective of the Human Eye

This fast, standard focal length offers a natural perspective comparable to the human eye for a wide variety of applications. The Planar T* 2/50 ZM provides high imaging performance at full aperture, making it possible to use a shallow depth of field without compromising image quality. Combined with a digital rangefinder camera with a 1.3 crop factor, the lens has an effective focal length of 65 mm, ideal for portraits.

Important specifications

Focal length 50 mm
M8 equivalent 65 mm
Aperture range 2 - 22 (1/3 steps)
Aperture blades 10
Focusing range 0.7 m – infinity
No. of elements/groups 6/4
Angular field, diag./horiz./vert. 47/39/27 °
Filter M 43 x 0.75
Dimensions (with caps) ø 52 mm, length 68 mm
Weight 230 g

Performance Data

The following graphs were gleaned from the Zeiss-provided datasheet (PDF) for this lens:

Introduction

A full review of the Zeiss Planar T* 2/50 ZM lens, including specifications, performance charts, overview, sharpness and vignetting tests as well as sample images and links for further research.

The Zeiss Planar T* 2/50 ZM lens compares directly to the Leica Summicron 50mm f/2 in many ways. They're of the same focal length, speed, diameter and weight, neither lens utilizes aspherical elements and both offer fantastic (if not identical) image quality. While the Summicron has a slight bit of an edge as far as lens size goes (it's 5mm shorter when using hoods and blocks less of the finder), the Planar costs an awful lot less money (in fact, it's one of the least expensive ZM lenses available). Though in favor of the Summicron, it offers 6-bit coding from Leica and a slide-out hood in the latest version. Ironically, the Summicron is also a planar design!

The Planar T* 2/50 ZM lens is very similar to the Biogon T* 2/35 ZM lens as far as size, weight, the filter size of 43mm and overall looks. Compared with the C Sonnar T* 1,5/50 ZM it's a narrower, longer lens. Where it really differs is the rendition. Some describe the Planar as a "modern" lens whereas the Sonnar is more of a "classic" lens. That is to say, the Planar is sharper and more well-corrected generally but sacrifices the character (and nearly a full stop of speed) that the C Sonnar brings to the table.

The planar lens was designed by Paul Rudolph of Carl Zeiss back in 1896 and consisted of six elements, four groups in a symmetrical layout. It was sharp even in its original form and this new version (which shares an essentially identical design) is no different. Through careful design and T* coatings, the biggest problem of the original - flare - has been essentially eliminated. The planar design is actually one of the most common in the world, copied by nearly everyone in one form or another and is often referred to as double gauss (so named after Carl-Friedrich Gauss). The Sonnar design, ironically - was created by Dr. Ludwig Bertele back in 1924. So any comparison to "modern" or "classic" lenses is strictly meant in a rendition sense - not the designs themselves.

Consider reading about all the things they have in common in our Zeiss ZM Lenses overview.

The Lens

Like the other ZM lenses, the Planar is well-built and solid-feeling. The materials and craftsmanship are both of a high-order. The aperture ring has positive, somewhat firm detents from f/2.8 to f/22 in third-stops. This differs from the Leica standard of half-stops, so it's something to keep in mind if you have a mixed bag. It's useful especially if you shoot slide film but also with the M9 if you're used to dialing in exposure compensation - which is also in third-stops. The focus ring is smooth and well-damped, but not as much as Leica lenses.

Wide open at f/2 the lens is already very sharp - but more towards the center, with some slight softness in the corners and edges. Stopping down to f/2.8 improves upon this all around as the field flattens out. Stopped down to f/4, the lens is at its optimum in the center, but stopping down to f/5.6 gives you a slightly flatter field (at the cost of some of the center resolution). Beyond, at f/8 and smaller diffraction starts to set in. You can shoot this lens wide open or stopped down without worry.

Contrast, while a bit lower wide open, improves at f/2.8 and again at f/4 where the lens is about optimum - and remains that way stopped down further. Overall, average contrast is on the higher side.

Distortion isn't as well controlled as some other ZM lenses (like the Biogon T* 2/35 ZM) as there is a very slight barrel distortion - but it is quite minimal. You'd really have to shoot test targets to even see it. The lens exhibits some vignetting wide open but clears up quickly. By f/2.8 it's already much improved and by f/4 essentially gone. In comparison, the Leica Summicron 50mm f/2 has similar vignetting (which is why the lens coding works so well in this regard) though slightly less distortion.

Bokeh is pleasant, very similar to other ZM lenses in that it's not super smooth and washed away as a sea of color - there's still some detail to it. Flare resistance is outstanding, as expected. With ten aperture blades and stopped down, sunstars are brilliant. Colors are deep and saturated, especially blues and greens. Very much a Zeiss lens.

You could almost call the Planar a "boring" lens - in the sense that's it's close to perfection. While there's very minor softness in the corners/edges and some vignetting wide open to around f/2.8 - from f/4 onwards, it's game on, full speed ahead. We wish we could write more about it, but there's little left to be said! it's about as sharp as lenses get with very reliable, predictable performance. It's easy to see why Leica hasn't yet brought out a Summicron-M 50mm f/2 in an ASPH version (though one is rumored) as it's hard to see where these lenses could be improved upon except for maybe wide open and Leica has even said as much.

The filter size is 43mm, which differs from the more common 46mm size of many other ZMs. Not a deal-breaker by any means, but something to consider if you're looking to share filters, especially UV/IR filters with other lenses. One great solution is a 43-46mm step ring and standardizing on 46mm filters. This way, you can use the filters on most of the ZMs without consideration and throw on the step ring for use with the Biogon T* 2/35 or Planar T* 2/50 ZMs as needed. It's worth noting that the Leica 43mm UV/IR filter is of a different thread pitch and will not work properly - though it can be screwed in to the point of binding a tiny bit and it'll hold just fine (do not exceed this point however).

Lens Hood

Unlike the Leica Summicron 50mm f/2 that it compares against, the Planar T* 2/50 ZM does not come with a hood; it's an optional accessory. Though for the money saved, it's not a big deal. While extremely flare resistant, the hood could be considered optional... But we always recommend using one.

Coding for Digital Ms

This lens is typically given the 6-bit code of the Leica Summicron 50mm f/2 (11819/11825 or 11826/11816 for "type IV/V") - which works well on both the M8 and M9 bodies. The code for this is 100001 and can be either marked with a template and a Sharpie marker or machined into the flange and properly painted for a more permanent solution via a third-party. The 50mm focal length doesn't typically need to be coded for in-camera corrections, at least - but is still useful for the EXIF info and to differentiate between lenses.

Other Thoughts

As mentioned earlier, and especially compared to the Leica equivalent - the price point of the Planar T* 2/50 ZM lens is excellent and is among the cheapest of the ZM line. If you're looking for a rock-solid lens to start off your kit, this one should be on your short list.

While an f/2 lens might not sound as sexy as an f/1.4 (or faster) lens, the tradeoff is a much simpler lens with a smaller size, less weight and lower cost. There's no real need for aspherical or floating elements and any corrections necessary are very minor. There are slower 50mm lenses out there, but won't gain you much as far as performance goes (as is often the case with slower lens designs). You could easily use an f/2 lens as an everyday shooter in all but very dim conditions - where a case could be made to have an additional lens at this most popular focal length. For example, the C Sonnar T* 1,5/50 ZM would make a great companion for when you need the extra speed or desire more "character" to the image.

Just one more comparison to the C Sonnar T* 1,5/50 ZM as many will wonder which lens they should get. As mentioned earlier, the Planar is often referred to as "modern" whereas the Sonnar is more "classic" in rendition (despite the actual designs being the opposite and then only 28 years apart at that). The problem with the Sonnar is that it exhibits focus shift - something the Planar lacks. While people looking for "character" can overlook this and consider the results worthy of the extra trouble, for more "every day" shooting the Planar is a safer, easier choice - especially for beginners.

On the M8, keep in mind that the lens is equivalent to a 65mm. While great for many things, some might prefer a wider lens for every day shooting - something closer to an actual 50mm. A great alternative to consider might be the Biogon T* 2/35 ZM. Similar to the Planar - but wider. You might even consider using the Biogon T* 2,8/25 ZM which is closer to a 35mm.

Vignetting

Vignetting was tested using the M9 at ISO 160, firmware version 1.162:

Lens detection set to OFF

f/2.0

f/2.8

f/4.0

f/5.6

f/8.0

f/11.0
 
Lens coded as a Summicron 50mm f/2 (11819/25 or 11826/16 for "IV/V") and lens detection set to AUTO

f/2.0

f/2.8

f/4.0

f/5.6

f/8.0

f/11.0
 
Lens coded as a Summilux 50mm f/1,4 ASPH (11891/11892) and lens detection set to AUTO

f/2.0

f/2.8

f/4.0

f/5.6

f/8.0

f/11.0

Sharpness

This test is preliminary, and only tests the center performance - but it should give you an idea of what to expect. It was conducted by shooting a test target at MFD (.7m) which represents a worst case scenario as non-macro lenses are generally optimized for infinity. Images were shot at the various apertures with an M9, mounted on a tripod. No alterations were done to the image except for auto level and they are 100% crops:

f/2 f/2.8 f/4 f/5.6 f/8

Sample Images

Flickr Pool Images

Further Research

Sample images thread in forum
 
   
Planar T* 2/50 ZM zeiss.com
ZM Planar 50mm flickr.com
Carl Zeiss 2/50 Planar T* Review photoog.com
Zeiss 50mm f/2 ZM Review kenrockwell.com
Zeiss Planar T* 50mm f/2 ZM on Sony NEX photozone.de
Fifty 50s and The Zeiss Planar T* 2/50 ZM theonlinephotographer.blogspot.com
Zeiss ZM 50 Planar Lens Review stevehuffphoto.com