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Zeiss 21mm f/2.8 ZM
LEICA M Mount Biogon (2004-)
© 2011 KenRockwell.com. This page best with Corporate S regular and bold activated.

Intro   Specs   Performance   Compared   Recommendations

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Zeiss 21mm f/2.8 ZM

Zeiss 21mm f/2.8 ZM in silver (46mm filters, 9.105 oz./258.1g, about $1,340, also comes in black). enlarge. This free website's biggest source of support is when you use these links, especially these directly to it at Adorama in silver or in black, or at Amazon in silver or in black, or locally at OC Camera, when you get anything, regardless of the country in which you live. Here's the link to the optional hood at Adorama or at Amazon, and to Zeiss's 21mm finder at Adorama or at Amazon. It helps me keep reviewing these specialized lenses when you get yours through these links, thanks! Ken.


January 2011   Zeiss Reviews  LEICA   LEICA Lenses   Voigtländer   All Reviews

How to Use Ultrawide Lenses

Zeiss 21mm f/4.5 ZM Review

LEICA ELMARIT-M 21mm f/2.8 ASPH Review

Voigtländer 21mm f/4 Review

21mm Viewfinders


Introduction         top

Intro   Specs   Performance   Compared   Recommendations


Ritz Camera

I personally buy from Adorama, Amazon, Ritz, B&H, Calumet and J&R. I can't vouch for ads below.


The Zeiss 21mm f/2.8 ZM lens for LEICA is superb. It is as good as the LEICA ELMARIT-M 21mm f/2.8 ASPH, for less than one-third the price.

While the LEICA lens is only very slightly sharper, visible only under critical test conditions, visible only in the sides and corners, visible only on a LEICA M9, and visible only at the largest apertures, this Zeiss lens is superior because it has less distortion, less weight, takes more standard 46mm filters, goes to f/22, has a 10-bladed diaphragm, focuses closer to 0.5 meters, and is made entirely of metal. By comparison, the LEICA lens has a plastic focus tab, only stops down to f/16, only focuses to 0.7 meters, has more distortion and takes less compatible 55mm filters.

One will never seen any sharpness difference on film, where grain hides it. Only on the LEICA M9, only under direct comparison under the most stringent professional test conditions, only at the largest apertures, and only at the sides and corners is the very slightest difference in sharpness barely visible. The Voigtländer 21mm f/4 or even the best 21mm SLR lens or zoom is nowhere near the performance of this Zeiss or the LEICA 21mm lenses.

I'd never be able to discern any sharpness difference between the LEICA and this Zeiss in actual photographic conditions, but I would notice the difference between the hokey 8-pointed sunstars of the LEICA lens and the superior 10-pointed sunstars of this Zeiss, as well as appreciate that 46mm filters are far more likely to integrate well into a complete LEICA system than the oddball 55mm filters of the LEICA 21mm lens. To wit, a perfect state-of-the-art fielded system can be this Zeiss 21mm, the LEICA SUMMILUX-M 35mm f/1.4 ASPH FLE, LEICA SUMMILUX-M 50mm f/1.4 ASPH, LEICA ELMARIT-M 90mm f/2.8 and LEICA ELMAR-M 135mm f/4, all of which take 46mm filters. If you made the mistake of trying to field the LEICA ELMARIT-M 21mm f/2.8 ASPH instead, you'd need to carry a second set of 55mm filters.

Zeiss has been a pain in LEICA's side ever since the 1930s, and this extraordinary ZM lens is no help. It works as well as the LEICA lens for a third the price, and handles better.

The LEICA photographer never frets the price, and even at the same price, this Zeiss lens has advantages over the LEICA ELMARIT-M ASPH. I don't find the sharpness difference to matter at all; make your choice on your preference of more significant factors like distortion, filter size, the diaphragm or weight.

Zeiss ZM 21mm f/2.8.

Zeiss 21/2.8 ZM. enlarge.



This LEICA-M mount lens works perfectly on every LEICA M ever made, from the LEICA M3 of 1954 through today's LEICA M9.

It also works on every other LEICA M mount camera, like the Minolta CLE, Zeiss Ikon and those dirty little Voigtländers.

When used on the LEICA M9, the 21 f/2.8 11134 profile works best. As I'll show under falloff, it gives nice, even results without color shifts on the sides.



TTL meters in cameras like the CLE, Zeiss Ikon, Konica Hexar RF, LEICA M6, LEICA M6 TTL, LEICA M7, and LEICA M9 work fine with this lens.



On any kind of camera, use any kind of external 21mm finder. You don't have to use Zeiss' own finder. The Zeiss finder is very nice, and is less expensive than LEICA's, but it doesn't matter.


Specifications         top

Intro   Specs   Performance   Compared   Recommendations


Zeiss calls this the Carl Zeiss Biogon 2,8/21 ZM T*.

Biogon is Zeiss' trademark for reasonably symmetrical wide-angle lenses.

More from Zeiss on the Biogon.

ZM means LEICA M mount.


Optics        top

Zeiss 21mm f/2.8 ZM internal diagram

Internal Diagram, Zeiss 21mm f/2.8 ZM. enlarge.

9 elements in 7 groups.

T* is Zeiss' trademark for their multicoating.


Actual Focal Length      top

Zeiss doesn't share the exact design focal length. When measured, it is the same as the Zeiss 21mm f/4.5 ZM and Voigtländer 21mm f/4.

The LEICA ELMARIT-M 21mm f/2.8 ASPH, whose precise focal length is specified as 21.3mm, has a few percent shorter focal length than these other lenses. The LEICA lens a slightly wider angle of view than the others.

Thus the actual focal length of this Zeiss 21 2.8 is a little longer than 21.3mm.


Diaphragm       top

Zeiss ZM 21mm f/2.8.

Front, Zeiss ZM 21mm f/2.8 at f/5.6. enlarge.

10 straight blades.

Stops down to f/22.

Third-stop clicks.


Angle of View        top

80º by 58º (90º diagonally).


Close Focus       top

0,5 meters (1.64 feet or 19.7").

The lens focuses this close, but the rangefinders of most modern LEICAs only couple as close as 0.7m, while older LEICAs like the LEICA M3 only couple to 1 meter.

To focus down to 0,5 meters, use a tape measure as we do in Hollywood (or guess), and set it on the lens.

LEICA's lenses don't focus this close.


Maximum Reproduction Ratio        top


Area covered: 47 x 71 cm, rated.


Depth-of-Field Scale       top

Yes, but it only goes to f/16.

Oddly f/22 is excluded. Oops!


Size        top

Zeiss specifies 75mm long by 53mm diameter.


Weight        top

9.105 oz. (258.1g), measured.

9.9 oz. (280g), specified.


Hood        top

The precision metal hood (part nr. 1365-665) isn't included, which is too bad, since it's very nice.

It sells for about $85 at Adorama or at Amazon.

It also fits the Zeiss 25mm f/2.8 ZM.

Zeiss' metal hood is much sturdier than LEICA's plastic hoods.

This Zeiss hood bayonets and locks. The only way to get it off is by firmly pushing it towards the camera to unlock and then rotating. It is spring loaded so it will never fall off, unlike LEICA hoods.


Introduced        top

Announced 28 September 2004, at Photokina.


Shipping since         top



Part Numbers        top

Black Lens: 1365-651.

Silver Lens: 1365-650.

Hood: 1365-665.


Scope of Delivery        top

You only get the lens, caps and fancy paperwork.

The hood is $85 extra.


Made in        top



Performance         top

Intro   Specs   Performance   Compared   Recommendations

Overall   Color  Diaphragm Calibration   Distortion  Ergonomics   

Falloff   Filters   Finder Blockage   Flare and Ghosts   Focus    

Lateral Color Fringes   Materials & Construction    Sharpness   Sunstars


Overall     performance   top

The Zeiss 21mm f/2.8 ZM is as good a 21mm lens as I've ever tested. Only the LEICA ELMARIT-M 21mm f/2.8 ASPH is a tiny bit sharper, but only under careful test conditions, only at the sides and corners, and only at the largest apertures.


Color Rendition     performance   top

I see no differences among this lens, the Zeiss 21mm f/4.5 ZM, the LEICA ELMARIT-M 21mm f/2.8 ASPH or Voigtländer 21mm f/4.


Diaphragm Calibration     performance   top

The calibration is right-on: the meter in my M9 tracks each full-stop perfectly throughout the entire range, except of course for the largest aperture.


Distortion     performance   top

The Zeiss ZM 21/2.8 has no visible distortion. This is better than the LEICA ELMARIT-M 21mm f/2.8 ASPH or Voigtländer 21mm f/4. The Voigtländer has a little barrel distortion, and the LEICA ASPH has a bit of bulging distortion in the center of its image. Even shooting brick walls, this Zeiss ZM 21 2.8 is flat. Zeiss claims that the Zeiss 21mm f/4.5 ZM has a bit less distortion, but since the little distortion in this lens is invisible, I wouldn't worry about it.

If you blow up M9 images to 200% and drop rulers on them, try a value of -0.9 in Photoshop's Lens Distortion Correction Filter to correct this Zeiss 21/2.8 at 3 meters (10 feet), after which it will retain a little bit of residual waviness, none of which is visible without a ruler for comparison.

Here is Zeiss' claimed distortion curve, however Zeiss doesn't specify the distance at which it is measured.


Claimed Distortion, percent

Distortion, ZEISS 21mm f/2.8 ZM

Distortion, Zeiss 21mm f/2.8 ZM. (image height, millimeters ->)


Ergonomics     performance   top

Zeiss ZM 21mm f/2.8.

Zeiss ZM 21mm f/2.8. enlarge.


Zeiss ZM 21mm f/2.8.

Bottom, showing focus nubbin, Zeiss ZM 21mm f/2.8. enlarge.

Ergonomics are wonderful.

The numbers and their indices are easy to read in any light, except that the red footage markings on the black version are invisible in anything other than daylight. They are much clearer in these pictures than they are in practice. The silver lens is always easy to read.

Focus is silky-smooth, has no play, and slides with a fingertip. There is one raised metal nubbin to help you focus with just one finger, as well as be able to set distance by feel in the dark.

Focus is geared quickly, so focus is very fast.

The aperture ring also flicks with a fingertip. It has a detents at third stops, and the full stops aren't more deeply detented, so if you count clicks as I do, it can become confusing if you shoot LEICA lenses at the same time.


Falloff (darker corners)     performance   top

Falloff is minor on a LEICA M9, so long as you select the profile for the 21mm f/2.8 11 134 lens (press MENU > select Lens Detection > press Set > select Manual > press Set > select 21 f/2.8 11134 > press Set).

If you don't select this profile, you'll see horrendous color shifts in the periphery caused by the rear nodal point of this lens being close to the sensor, and its light hitting the wrong CCD wells after passing through the sensor's microlenses. It's the same with LEICA's own 21mm lenses.

I usually show this in monochrome for other lenses, but for these, I've shown this in color so you can see the color shifts.

With the profile, the color shifts are invisible in photography , even though they are slightly visible here under my devious gray-on-gray presentation.

Without the correct profile selected, images will be unusable. Don't select the 21 ASPH profile, it doesn't work as well as the 21 f/2.8 11134 profile.


Zeiss ZM 21mm f/2.8 falloff on full-frame M9 at infinity, 21/2.8 11134 profile:


© 2011 KenRockwell.com. All rights reserved.


Zeiss ZM 21mm f/2.8 falloff on full-frame M9 at infinity, no profile:


© 2011 KenRockwell.com. All rights reserved.



Here are Zeiss' claimed falloff curves:

Claimed Illumination, percent

MTF, ZEISS 21mm f/2.8 ZM

Zeiss 21mm f/2.8 ZM (f/2.8 ü f/5.6, image height, millimeters ->).

These match the curves shown in LEICA's Technical data for the 21mm f/2.8 ASPH.


Filters, use with     performance   top

Any standard 46mm filter works great, with no vignetting. Be careful; thicker rotating filters may start to vignette.

Don't use polarizers on ultrawide lenses; they make the sky look funny.

If you use a 46mm -> 52mm adapter, thinner 52mm filters, like Nikon, are fine, while thicker ones, like traditional Tiffen, may vignette just a bit. Adapting to larger filters won' be a problem.


Finder Blockage     performance   top

Finder blockage is negligible; the same as with the LEICA ELMARIT-M 21mm f/2.8 ASPH.

LEICA 21mm blockage, no hood

As seen through a LEICA 12 008 21mm finder.

If this disturbs you, choose the Zeiss 21mm f/4.5 ZM or the tiny Voigtländer 21mm f/4 instead.


Flare and Ghosts     performance   top

With the disk of the sun in the image, sometimes you'll get a yellow blob opposite the sun. You don't get the two small magenta dots near the sun that you'll get with the LEICA ELMARIT-M 21mm f/2.8 ASPH in the same conditions.


Focus     performance   top

Focus is smooth and slick. It's easy to move with a fingertip, and is geared for fast focus.

Focus accuracy is never an issue with 21mm rangefinder lenses.


Lateral Color Fringes     performance   top

There no color fringes anywhere.


Materials and Construction     performance   top

Rear, Zeiss ZM 21mm f/2.8

Rear, Zeiss ZM 21mm f/2.8. enlarge.

This Zeiss is made very, very well, more solid in fact than the LEICA ELMARIT-M 21mm f/2.8 ASPH which costs more than three times as much, but economizes with a cheap plastic focus tab, instead of solid metal as with this Zeiss lens.

Filter threads and hood mount: Probably chromed brass.

Barrels, aperture and focus rings: Seem like aluminum.

Finish: Matte silver anodized or semi-gloss black enamel. Silver seems like a close enough match to a LEICA M3 or a chrome M6 TTL.

Focus helicoids: Seem like brass.

Mount: Chromed brass.

Markings: Engraved and filled with paint.

Blue index dot: Plastic.


Sharpness     performance   top

The more you know about photography, the more you know that lens sharpness doesn't matter.

Of course this Zeiss lens is insanely sharp. Zeiss has been making the world's best photographic lenses since the 1800s, long before LEICA or anyone else today, and Zeiss makes the optical test equipment used by many of these other lens makers. This lens costs over $1,000 at discount. What were you expecting, Voigtländer or Nikon quality?


As tested on a LEICA M9 at infinity

This Zeiss is sharp all over on a LEICA M9, even at f/2.8. In the center, it's always critically sharp, even at f/2.8. These comments refer to the periphery.

f/2.8: The far corners are a tiny bit less sharp than the center, but still sharp. It's a lot better than the Voigtländer 21mm f/4, and only a hair less sharp than the LEICA ELMARIT-M 21mm f/2.8 ASPH.

f/4: It's sharp and contrasty all over, although the region of image height around 12mm is a little bit softer. The very farthest corners are a tiny bit softer, visible only under very critical conditions.

f/5.6: It's sharp and contrasty all over, although the region of image height around 12mm is a little bit softer.

f/8: It's sharp and contrasty all over. f/8 is about optimum throughout the entire frame.

It's so good you'll probably never see any of this in anything but dedicated tests shot at infinity.

In real shots and on film, it performs perfectly. Any lack of sharpness will be your fault, not the lens.'


Here are Zeiss' claimed MTF curves:

Claimed MTF, percent at f/2.8

MTF, ZEISS 21mm f/2.8 ZM

MTF, Zeiss 21mm f/2.8 ZM at f/2.8. (10, 20 ü 40 c/mm, image height, millimeters ->)


Claimed MTF, percent at f/5.6

MTF, ZEISS 21mm f/2.8 ZM

MTF, Zeiss 21mm f/2.8 ZM at f/5.6. (10, 20 ü 40 c/mm, image height, millimeters ->)


Sunstars     performance   top

With a straight 10-bladed diaphragm, the Zeiss 21/2.8 makes 10-pointed sunstars on brilliant points of light.


Compared         top

Intro   Specs   Performance   Compared   Recommendations

I've been making comparisons throughout this review, starting at the first paragraph.

The Zeiss' optics and mechanics are as good as LEICA's. Your choice will be decided by your preference for filter size and other factors. If you are not a LEICA shooter and worry about price, then duh, get this Zeiss as fast as you can.


Leica vs Zeiss 21mm

Zeiss 21mm f/2.8 ZM (silver) and Zeiss 21mm f/4.5 ZM (black). bigger.


Zeiss 21/2.8 ZM
Finder Blockage
9/7 ASPH
10 blades
10 blades
8 blades
10 blades
7 blades
Aperture ring clicks
third stops
third stops
half stops
half stops
full stops
Close focus
very good
slightly bloated center
slight barrel
Minor yellow blob opposite
Minor, two magenta dots
some veiling
Minor, if any
Use on M9?*
Contax only
180g claimed
$800 used

* They work, however the M9 lacks any correction profile that will provide clean sides and corners. Crazier people waste time with special software to try to make these work, but duh, if you have enough money to throw away on a depreciating M9, you have enough to invest in the right lenses for it, which only go up in value.

** Actual measured.

This 21mm f/2.8 ZM has a similar, but different, design to the Zeiss Biogon 21mm f/2.8 lens for Contax G. The Contax-mount lens has less distortion, due to its design placing the rear nodal point closer to the image plane. This makes the Contax-mount lens less suitable for metering with LEICA M, and unsuitable for use with the CCD of the LEICA M9. This Zeiss ZM lens works great with the M9.


Recommendations         top

Intro   Specs   Performance   Compared   Recommendations

Deployment   More Information

This Zeiss 21mm f/2.8 is one of the best lenses available for LEICA at any price.

If price matters, get this lens immediately, and don't even consider the LEICA ELMARIT-M 21mm f/2.8 ASPH. The LEICA lens isn't any better, but costs over three times as much.

This f/2.8 Zeiss works great on the LEICA M9 because the old LEICA ELMARIT-M 21mm f/2.8 (made in Canada 1980-1997, Verk. Nr. 11 134) lens just happens to have had its rear nodal point in about the same position as does this Zeiss lens, therefore its profile works great with this lens. Don't use the Zeiss 21mm f/4.5 on a LEICA M9, because the f/4.5 lens' rear nodal point is much closer to the image plane, in a position for which there is no suitable profile available in the M9.

If you find the time I take to research all this helpful, my biggest source of support is when you use these links, especially these directly to it at Adorama in silver or in black, or at Amazon in silver or in black, or locally at OC Camera, when you get anything, regardless of the country in which you live. Here's the link to the optional hood at Adorama or at Amazon, and to Zeiss's 21mm finder at Adorama or at Amazon. It helps me keep reviewing these specialized lenses when you get yours through these links, thank you! Ken.


Deployment        top

I'd pass on the 1365-665 hood. It doesn't do much to reduce flare, but gets in the way.

Zeiss' dinky 46mm front cap is weak. I'd toss it, and buy a real 46mm LEICA cap for it.

For use with color transparency film outdoors, I prefer a 46mm B+W 81A filter.

For B&W outdoors, you want a yellow filter standard, like the B+W 46mm #022.

For color print film or digital, you want a LEICA 46mm silver-ring UV filter for protection.

(the old M8 needed a LEICA 46mm silver-ring IR filter.)


More Information

Zeiss' technical data.

Zeiss' glossy flyer about this 21mm.

Zeiss' glossy brochure on the ZM lenses.


Help me help you         top

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The biggest help is when you use any of these links to Adorama, Amazon, eBay, Ritz and Calumet when you get anything. It costs you nothing, and is this site's, and thus my family's, biggest source of support. eBay is always a gamble, but all the other places always have the best prices and service, which is why I've used them since before this website existed. I recommend them all personally.

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Thanks for reading!

Mr. & Mrs. Ken Rockwell, Ryan and Katie.

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