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Zeiss 21mm f/4.5 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/4.5 ZM

Zeiss 21mm f/4.5 ZM in black (46mm filters, 6.9 oz./195g, about $1,120, also comes in silver). 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 locally at OC Camera, when you get anything, regardless of the country in which you live. Here's the link 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/2.8 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/4.5 ZM lens for LEICA is superb. This Zeiss lens is better than the LEICA ELMARIT-M 21mm f/2.8 ASPH because this Zeiss lens is sharper, has less distortion, has fewer ghosts, weighs less, 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 ELMARIT-M 21mm f/2.8 ASPH economizes with a plastic focus tab, the LEICA lens isn't quite as sharp, it has more distortion, it takes a unique 55mm filter, it has a dorky 8-bladed diaphragm, it only stops down to f/16, and the LEICA lens only focuses to 0.7 meters.

The only thing one gets for spending four times as much for the LEICA lens is 1-1/3 stops more speed, but if you need speed, the Zeiss 21mm f/2.8 ZM offers the same speed as the LEICA ELMARIT-M 21mm f/2.8 ASPH, and offers most of the advantages of this f/4.5 lens at almost as low a price.

This f/4.5 lens is not for use on the LEICA M9 because its rear nodal point is not in a position for which the M9's internal lens profiles can compensate. If you're shooting an M9, get the Zeiss 21mm f/2.8 ZM or LEICA ELMARIT-M 21mm f/2.8 ASPH instead, because their rear nodal points are in positions for which the 21 f/2.8 11134 profile compensates quite nicely.

If you use this f/4.5 lens on an M9, you'll get nasty color shifts on the sides. Only an idiot would expend the effort to use special software to try to compensate for this lens on an M9, when the Zeiss 21mm f/2.8 ZM or LEICA ELMARIT-M 21mm f/2.8 ASPH work so much better — on the M9. If you have an M9, whose value depreciates by thousands of dollars a year, you easily can afford to buy any lenses you want, whose value only increases with time.

I'd never be able to discern any sharpness difference between the LEICA and this Zeiss in actual photographic conditions, but I will 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 FLE ASPH, 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 one quarter 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 — or if you're shooting the M9 instead of a proper camera.

Zeiss ZM 21mm f/4.5.

Zeiss 21/4.5 ZM. enlarge.



This LEICA-M mount lens works perfectly on every real LEICA M ever made, from the LEICA M3 of 1954 through today's LEICA M7 and LEICA MP.

Don't bother using this lens on the LEICA M9, as this lens' rear nodal point isn't in a position to which the M9 can adapt itself, and will thus condemn you to either color-shifted corners, or software drudgery to fix what wouldn't have been a problem if you shot the Zeiss 21mm f/2.8 ZM or LEICA ELMARIT-M 21mm f/2.8 ASPH instead.

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



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 4,5/21 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/4.5 ZM internal diagram

Internal Diagram, Zeiss 21mm f/4.5 ZM.

8 elements in 6 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/2.8 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 4.5 is a little longer than 21.3mm.


Diaphragm       top

Zeiss ZM 21mm f/4.5.

Front, Zeiss ZM 21mm f/4.5 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: 48 x 72 cm, rated.


Depth-of-Field Scale       top

Yes, but it only goes to f/11.

Oddly f/16 and f/22 are excluded. Oops!


Size        top

Zeiss specifies 31mm long by 53mm diameter.


Weight        top

6.869 oz. (194.7 g), measured.

6.7 oz. (190g), specified.


Hood        top

There is no hood offered for this lens. Who cares? It sees such a wide angle that a hood won't do anything differently than the filter threads alone.


Introduced        top

Announced at Photokina, 28 September 2004.


Shipping since         top



Part Numbers        top

Black Lens: 1419-575.

Silver Lens: 1419-574.


Scope of Delivery        top

You get the lens, caps and fancy paperwork.


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/4.5 ZM is the sharpest and the least distorting 21mm LEICA-mount lens that I've ever tested. Even LEICA's own ELMARIT-M 21mm f/2.8 ASPH isn't as sharp, although the margin is so small that I'd never notice it outside of direct comparisons under exacting test conditions.

Don't bother with the LEICA M9 with this lens. The M9's sensor can't optimize itself to handle a rear nodal point so close to its sensor. This f/4.5 lens is designed for serious artists working in 35mm, not for the idle rich and their digital snapshot cameras.


Color Rendition     performance   top

I see no differences among this lens, the Zeiss 21mm f/2.8 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 21/4.5 has no visible distortion. This is better than the LEICA ELMARIT-M 21mm f/2.8 ASPH , Zeiss 21mm f/2.8 ZM and Voigtländer 21mm f/4.

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


Claimed Distortion

Distortion, ZEISS 21mm f/4.5 ZM

Distortion, Zeiss 21mm f/4.5 ZM.


Ergonomics     performance   top

Zeiss ZM 21mm f/4.5.

Zeiss ZM 21mm f/4.5. enlarge.


Zeiss ZM 21mm f/4.5.

Bottom, showing focus nubbin, Zeiss ZM 21mm f/4.5. 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 impossible to show on an LEICA M9 because it has no profile to correct for the limitations of its CCD sensor.

Specifically, on an M9, the rear nodal point of this lens is so close to the sensor that the rays pass thought the microlenses and hit the wrong CCD wells, leading to bizarre color shifts for which none of the M9's in-camera profiles can compensate.

Don't use this lens on an M9, but I'll show you what happens anyway.

Zeiss' relative illuminance curves indicate similar performance to the Zeiss 21mm f/2.8 ZM and LEICA ELMARIT-M 21mm f/2.8 ASPH.

If you must, the best profile to use is 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).

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.


Zeiss ZM 21mm f/4.5 falloff on full-frame M9 at infinity, 21/2.8 11134 profile:


© 2011 KenRockwell.com. All rights reserved.


Zeiss ZM 21mm f/4.5 falloff on full-frame M9 at infinity, no profile:


© 2011 KenRockwell.com. All rights reserved.



Here are Zeiss' claimed falloff curves:

Claimed Illumination

MTF, ZEISS 21mm f/4.5 ZM

Zeiss 21mm f/4.5 ZM (f/4.5 ü f/8, 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 thick 46mm filter works great, with no vignetting.

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

If you use a 46mm -> 52mm adapter, even thicker 52mm filters, like traditional Tiffens, are fine.

Two stacked filters will vignette.


Finder Blockage     performance   top

There is no finder blockage.


Flare and Ghosts     performance   top

With the disk of the sun in the image, I didn't get any ghosts.

Under the same conditions, I got a yellow blob opposite the sun with the Zeiss 21mm f/2.8 ZM, two small magenta dots near the sun with the LEICA ELMARIT-M 21mm f/2.8 ASPH., and a slight yellow veiling with the Voigtländer 21mm f/4.

The flare and ghost performance of this Zeiss 21 f/4.5 is the best of any modern M-mount 21mm lens I've ever used.


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/4.5

Rear, Zeiss ZM 21mm f/4.5. enlarge.

This Zeiss is made very, very well, more solid in fact than the LEICA ELMARIT-M 21mm f/2.8 ASPH which costs four 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 (not seen on this particular sample).


Sharpness     performance   top

The more you know about photography, the more you know that lens sharpness doesn't matter, but if you care, this is the sharpest 21mm lens I've ever used in LEICA mount.

On a LEICA M9 at infinity, everything is always critically sharp, even at f/4.5 and even in the corners. I was surprised that on an M9 it was obviously sharper, viewed at 100% on a 30" monitor, than the LEICA ELMARIT-M 21mm f/2.8 ASPH.

Any lack of sharpness will be your fault, not the lens.'


Here are Zeiss' claimed MTF curves:

Claimed MTF at f/4.5

MTF, ZEISS 21mm f/4.5 ZM

MTF, Zeiss 21mm f/4.5 ZM at f/4.5. (10, 20 ü 40 c/mm, image height, millimeters ->)


Claimed MTF at f/8

MTF, ZEISS 21mm f/4.5 ZM

MTF, Zeiss 21mm f/4.5 ZM at f/8. (10, 20 ü 40 c/mm, image height, millimeters ->)


Sunstars     performance   top

With a straight 10-bladed diaphragm, the Zeiss 21/4.5 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 choice of camera, filter size and other factors.


Leica vs Zeiss 21mm

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


Zeiss 21/4.5 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 f/4.5 lens is for the most critical and serious photographic artists, not casual digital snapshooters.

Used on a real LEICA, this Zeiss 21mm f/4.5 is one of the best lenses available for LEICA at any price.

For use on film on LEICA, this is the best 21mm lens I've ever shot.

DO NOT USE THIS LENS ON THE LEICA M9. I've already covered that; use the Zeiss 21mm f/2.8 ZM or LEICA ELMARIT-M 21mm f/2.8 ASPH instead.

Seeing that this lens won't work on an M9, and that the Zeiss 21mm f/2.8 ZM is also extraordinary and 1-1/3 stops faster, I'd suggest the f/2.8 model for most people.

Shot on film as this lens shall be shot, I doubt that I could see any difference between the slightly greater sharpness of this lens versus the Zeiss 21mm f/2.8 ZM or LEICA ELMARIT-M 21mm f/2.8 ASPH. Likewise, the distortion of the Zeiss 21mm f/2.8 ZM is invisible unless you pull out a ruler at 200% magnification, so I'd opt for the Zeiss 21mm f/2.8 ZM over this f/4.5.

Don't forget your choice of 21mm finder, any will do.

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 locally at OC Camera, when you get anything, regardless of the country in which you live. Here's the link 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

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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Thanks for reading!

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

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