Leica vs. Contax lenses

[wilhelm]

As long as I'm getting answers to old questions, I'd like to ask our experts how Zeiss managed to make their 50mm Contax lenses all to rangefinder couple to the cam in the body, while Leica requires individual cams cut for each lens. Was the Zeiss manufacturing process so much more exact that they made every lens exactly the same focal length? I note that their other lenses (which mount on the external ring), all have individual cams just like a Leica (pun intended). Also, has anybody noticed the DOF marks on the Contax body are about two stops more generous than the Leica 50mm lenses. Were they just calculated for different COC, or did Zeiss think their lenses were that much better?

[silverfish1]

I am no expert but ... In case your faced with the question in a

trivia pursuit game the "M" comes from the German word messen which

means to measure. The Zeiss glass in the Contax IIa and similar

vintage pieces may indeed have been better optically than concurrent

Leica glass, but the 90mm baselength of the Contax rangefinder over

the 73mm of the Leica III was probably more forgiving. Some "M"

lenses won't work as well on the CL for these reasons. The achilles

heel of the early Contax was it's shutter. The Leitz shutter today is

still essentially the same design as the III. The design of M3 and

forward to the M4 relied on hand finishing but also tight

manufacturing tolerances. You can adjust the cant of the rangefinder

coupling roller on a pre M4-2 body and correct for alignment error in

the rangefinder patch. Cams wear like all metal surfaces.

[andrew_schank]

The old Contax cameras may have had a wider rangefinder base, but you

ended up looking through a teeny tiny hole in the back of a fairly

dingy finder for focusing. Depth of field scales are determined by

what a manufacturer considers acceptable sharpness, so they can

vary. I never heard of a lens having more depth of field than

another of the same focal length. I guess a lens that resolves nearly

100 LPMM would have more acceptable sharpness on the fringe of depth

of field than one that resolves 60 LPMM, but I'm not 100% certain of

it.

[silverfish1]

Yes Bill, I am not clear here either. The later version Contax had

the focus/ mounting ring/helicoid for the 50mm as permanent part of

the body. This allowed for a smaller lens. What did you mean

by "about two stops more generous"? Perhaps just having more physical

space for engraving made this distinction possible.

[wilhelm]

Marked hyperfocal distance of 16' is @f:16 for the Summicron, f:9 for

the Sonnar. At f:16 the Sonnar hyperfocal distance is 11'. Focused

at 12', the Summicron DOF @f:8 is 9-18' -- the Sonnar @f:8 is 7.5-

28'. It's like a free stop and a half, if you believe them. A 50mm

LST Nikkor f:1.4 exactly matches the Summicron, while a 50mm Xenon on

a Retina IIa is even more optimistic than the Zeiss (expained at

least in part because the Xenon is actually a little shorter than the

others).

[richard_oleson]

The Zeiss system didn't require more precision than Leitz. In both

cases, the combination of lens and body has to be extremely precise.

In the Leica, the focus helical is in the lens and the RF cam on the

lens must be ground to perfectly match the lens focus. In the

Contax, the focus mechanism is in the body and the lens cells must be

positioned perfectly in the barrel to make the system work. In both

cases, the design allowed for sufficient adjustment in the

manufacturing process to correct for part-to-part variability in the

glass.

 

<p>

 

The separate cams in the non-standard focal lengths are a mechanical

necessity, as the focus travel of these lenses does not match that of

the inner mount (similarly, non-standard Leica lenses use a ramped or

articulated RF cam for this purpose, where the 50mm cam is just the

flat rear face of the lens mount).

 

<p>

 

As far as differences in the DOF scale, I expect this was just the

result of a different circle of confusion being selected as the

standard for the scale, with Leitz being more strict. I doubt you'd

see a difference in an image.

 

<p>

 

The superiority of Zeiss lenses in the prewar period came mainly from

their use of complex cemented groups to minimize the number of

air/glass surfaces, thus minimizing flare. With the arrival of

antireflection coatings after the war, this became less of a benefit

as Leitz lenses improved dramatically.

 

<p>

 

rick :)=

 

<p>

 

rick_oleson.tripod.com

[silverfish1]

Subjective interpretation of objective criteria varies.

Depth of Field Tables published in the 11/61 edition of Modern

Photography give (General Photographic work) near point of 8',1.2"

and far Point of 13',1.2" for a 50mm lens focused to 10' @ f/8. For

Critical Work, the near point is 8',5" and the far point is 12',4".

The writer notes: "The variety of depth-of-field tables engraved on

lenses and on cameras, published by lens and camera manufacturers and

appearing in countless guides and data sheets very greatly in

consisitency and reliability. Many are hopelessly imprecise. ..."

Using a circle of confusion 1/20mm or 1/30mm would give very

different results than the accepted(?) 1/40mm for general photography

or the 1/50mm for critical amateur or professional work.

[wilhelm]

Okay, so the DOF marks are probably based on differing COC. Now back

to the original question: Are the Contax 50mm lenses all manufactured

or adjusted to the same focal length, or is there another mechanism

in action here?

[silverfish1]

Which 50mm? The sonnar for the I thru IIIa? The screw mount versions

for the Leica? The latest designs? BTW, as noted above, lens coatings

ultimately gave Leitz and others an optical advantage but the

invention of coatings are attributed to Carl Zeiss. He apparently

lost the control of the design rights inadvertantly. Most lenses

including Leica's are a nominal rather than actual focal length and

speed. Again circle of focus on the film plane like the COC is a

relative measurement. My GUESS is that Zeiss designs have this

tolerance as well.

[richard_oleson]

The Zeiss Sonnars could be adjusted in the barrel to bring the

infinity focus to perfect register (I think they used shims, but I'd

have to go back and look to be positive). Once this is done, the

lens-to-lens variability isn't enough to cause problems at the closer

distances. Kiev used a 50mm Jupiter and a 53mm Helios in the same

Contax mount, with good success.

 

<p>

 

rick :)=

[wilhelm]

Thanks Rick. Vellly interesssting. Humm, if it worked for Zeiss,

wonder why Leitz cut their cams individually for each lens? Or did

they?

[silverfish1]

I will take a guess that it has to do with parallax correction being

incorporated into viewfinder framelines in the Leitz designs. The

roller follows the (cam shape) timing precisely and continuously thru

the range for each lens. BTW the frameline's actual field of view

changes from nearest point to infinity. This has a minor effect on

metering in the M6.

[victor_randin3]

Good question, Bill. Just two my kopecks, please. The genuine focal

length (the distance between the focal plane and the plane of max.

sharpness) of any lens is not the same what is engraved on its front

shield, but the same for the whole generation of lens and its

formula. For example the focal length of any Sonnar 2/50 is about 52

mm (don�t remember the exact value). The acceptable error of focus

length is about 0.005-0.01mm.

Zeiss made every Sonnar the same focal length as well as Leitz made

every RF Elmar, Summar, Summitar, Summarit, Summicron, Sunmmilux and

the others its own, but also exactly identical focal length (depends

on lens name/formula and version/generation) in limits of acceptable

error. Only older Leicas (A, B, C) were matched to its Berek�s normal

lens (Leitz Anastigmat, Elkan, Elmar) individually through the hole

in the camera back.

Shapes of Zeiss and Leitz lenses cams are designed in different way.

Any Zeiss lens cam (for pre-M Leicas) has parallel working edge

machining made, while most of Leitz lens cams are of more complex

shape of declining working edge (on which marks of hand finishing are

visible). It may be suggested that individual cams cut for each Leitz

lens depending on its individual focal length. But its focal length

is identical. So, it is right in that sense that working length of

each cam is hand finished to match it to the identical lens focal

length value because of summary error appearing inevitable during

manufacturing process. M-lens cams are mostly machining made.

As it is known the lens cams for LF-cameras are individually made for

each lens, at least by Linhof. They buy lenses from Schneider, Zeiss,

Rodenshtok without cams.

Contax normal lenses are more small and simple in its design than

Leitz�s ones. They have neither helicoid nor cam. Sonnar lenses

4.0/21, 2.8/35, 2/85, 1.5/85, 4.0/135 (which mount on the external

lens seat) also have nor cams nor helicoids. The helicoid with the

lens seat is in the camera body and simultaneously plays a role of

the cam coupling to the lever of moving base of the RF prism.

Was the Zeiss manufacturing process so much more exact that they?

Seems, Zeiss had more advantages in that period. Famous Sonnar 1.5/50

was in producing from 1932, its coated version �T�� from 1935. But in

1932 Leitz from normal lenses had in producing only Elmar 3.5/50,

Summar 2/50, (maybe Hector too) and Leica II, III. Bad coated

Summitar was in producing only in 1939. Leitz Xenon 1.5/50

(Schneider�s formula) and then its analog Summarit appeared somewhere

in early �50s. Sonnar�s formula by Dr. Ludwig Bertele is much better

than Summar�s, the coating quality is also much better than

Summitar�s. The RF-base of Contax is about 110 mm, screwmount Leica

RF-base = 39mm. The quality of Zeiss lens is very high even today. I

have and use a few ones for Leica.

But then Leitz won the competition with his M3& Summicron.

I dont�t know why the DOF marks on the Contax body are about two

stops more generous than the Leica 50mm lenses. Maybe the genuine

focal length of Summicron is a little more than Sonnar�s (?),

somewhere about 54mm (?). But I did not meet exact value of any

version of Summicron�s focal length.

 

<p>

 

Regars,

Victor

[wilhelm]

Wow! I'd say that answer is worth two Rubles, not just two Kopecs.

Thanks!

[joe_buechler]

For what its worth, the DOF scales on my current Zeiss SLR lenses are

calibrated one stop faster that those on my Leica M lenses and Nikon

lenses. Zeiss has always used a different COC than Leica and Nikon.

And yes, you WILL notice the difference. I always stop the Zeiss

lenses down an extra stop when DOF is important.

[charles_lennox]

CONTAX - LEICA comparing shutter accuracy on the "CLASSICS" as a

year's project - M3 and earlier VS same units produced by Contax,

over same time frame: I have tested shutter accuracy on these old

clunkers, involving 23 Leica and 28 Contax and the results are a

story of remarkable inconsistancy! In general ALL of the Leica units,

ranging from Superfine ++++ condition to just working, had a MEAN

shutter differential of 47% against the cameras settings, on the SLOW

side while on a similar batch of Contax units the measurements are

very much superior, producing a MEAN differential of only 18% - the

ancient Leica shutter design of processed fabric are from the stone

ages, at best incapable of precision lasting into the 70 - 45 years

that have passed since they came out of the factory. The Contax

units, with metal shutter blades fared much better. In the same way,

the ancient lens design, materials and manufacturing methods of the

era created optics that are what they are - from a pre-space age

time, when all of the Leica/Contax 35's were at the leading edge of

the very limited technology of yesterday. Lens testing over a range

of product in the same shutter testing selections showed brutal

results in terms of flare, abberations, resolution characteristics,

and the like. Let's face it these are ancient cameras with out of

sight prices bid up by collectors and not modern photographers. In

modern terms the Contax C2 is a modern computer and the M6 is a

typewriter. In actual use, an M3 in tip top condition, and with a

variety of lenses, produce remarkable results - using B & W at ISO of

25 - get into modern film and that old baby is long in the tooth,

incapable of being compared picture taking wise with a Nikon 60 (body

at $300.00 or less.

[wilhelm]

Very interesting Charles. The incredible results some photographers

attain with these old clunkers is a testament to their skill and the

versatility of some modern materials. (Of course, some of the

greatest writers still happily use their Parker 57s -- no computers,

typewriters, or even BICs need apply).

[tony_brookes5]

Subject: Leica vs. Contax lenses

 

<p>

 

Charles has given a comprehensive answer to the question but as Bill

says it does not explain how such 'old' cameras can still give

remarkable results. I have always believed, based upon what I have

read and experience with Contax lenses, that this part of Contaxes

was superiorto Leitz. The Contax shutters were not so reliable - mine

failed - but according to Charles more accurate when working. On such

opinions are our views based but the proof is in the pictures. People

still use old Leicas and achieve remarkable results. How many

Contaxes are still used daily ? I do see the occasional Leica III

being used but I never see a Contax III. Am I wrong ? Where are you

pre-war Contax users ?

[MTC Photography]

There is a group of Contax rangefinder users:

<p> <a href="http://groups.yahoo.com/group/ZICG">Zeiss Ikon Collector

Group </a>

[MTC Photography]

Interest in Contax RF is evident from the production of miniature

Contax I

 

<p>

 

<a href="http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?

ViewItem&item=1309359569">Miniature Contax I</a>

just like miniature Leica IIIf, M3

[andy_piper2]

Bill:

 

<p>

 

Looks like you got most of your answers, but this might be a useful

addednda.

 

<p>

 

I THINK Contax used a very different "geometrical/mechanical" approach

to the RF mechanism.

 

<p>

 

The Leica RF measures how FAR the lens is from the film, via the cam

and roller connection. Each focal length has a cam to move the roller

IN AND OUT a given distance between (say) infinity and 1 meter.

 

<p>

 

What I've read is that the Contax/Nikon RFs measure BARREL ROTATION to

calculate lens position: i.e. ALL the various focal lengths ROTATE

through 115 degrees (or whatever) to move from infinity to 1 meter. The

lenses connect to the "50mm" focusing ring that is built into the

camera, and it is geared (not cammed) directly and permanently to the

RF mechanism.

 

<p>

 

RE: focal length variations. I thought Leica had 3-4 specific lens

barrel/cam shapes for 50s, and chose among them based on the actually

focal length measured after production - hence the little engraved

numbers on the barrel (00, 10, 22, etc.) - rather than hand-shaping

each and every cam.

 

<p>

 

Lens quality does not affect depth-of-field, per se - if anything, a

crummy lens should have MORE apparent depth-of-field because the

slightly OOF areas would be indistinguishable from the "sharpest"

areas. Dianas have great depth-of-field because ALL parts of the

picture are circles of confusion. 8^)

[MTC Photography]

Contax G1 G2 are quite interesting.

<p> However, I shall be quite excited if Contax can bring back

a genuine manual focus rangefinder with modern Biogon, Sonnar,

distagon, hologon...

[msitaraman]

Martin, now that would really set the cat amongst us Leica pigeons

here !

[furcafe]

[Wow, didn't realize this thread was still alive!]

 

<p>

 

Tony:

 

<p>

 

Another proud (pre & post-WWII) Contax user over here (Kyocera

G2, too)! I think the main reason a lot fewer people use the old

Contax RFs is that, unlike Leitz/Leica, Zeiss Ikon has been out of

business for 30 years & there's no current product line to

preserve interest in the brand & its heritage. [incidentally, this

relative lack of interest is 1 of the reasons why the Contax shutter

gets a bad rap for reliability--there aren't too many around that

have received proper maintenance over the years. The good

side is that Contax bodies & lenses are much cheaper than

Leica equivalents.] A lot of folks nowadays don't even know that

Contax cameras existed before the Yashica/Kyocera models.

Martin's right that the world would be a better place if Kyocera or

another manufacturer would come out w/a high end manual RF

system to give Leica some direct competition (perhaps not so

good for the Leica co.)--after all, it was the rivalry between Leitz &

Zeiss (& later Nikon & Canon) that inspired so many great RF

innovations. It's too bad Nikon didn't decide to come out w/a

modern M6-equivalent "S5" or "SP2" on the heels of the S3

commemorative.

[christoph_wagner]

Subject: Leica vs. Contax

I just seen this statements from december 01 and would like to answer

Tony:

I use the CZJ Sonnar T* lenses 1,5/50, 2,0/85 and 4/135 in M 39

screwmount (made in wartime for export) with my M 4 P and I´m a great

fan of that stuff. I prefer the Leica body for its quality and I do

think that this old Zeiss lenses are as good (perhaps better) as the

Summarits, Elmarits etc. Even the Summilux is matched by the f1,5

Sonnar. The Summicrons on the other side have a little more contrast

especially for B+W.

The old Contax cameras (pre- and postwar) were much more complicated

then the Leicas and therefore not so reliable.

I also think that prewar lenses as particular the Sonnars or the

Summar combined with today cameras and films are best for stunning

results, which you can not obtain with the SuperAchromatAPO-Lenses

from today.

Greetings