Zeiss lenses: G series versus ZI series?

[sircarl]

As Contax G owners know, one of the main reasons (for me, THE main reason) for owning a G1 or G2 is the superb Zeiss G series lenses that were made for these camera lines. Which started me wondering... how do the new ZI lenses for the Zeiss Ikon compare? Obviously, we're talking about a very different animal here. The ZI lenses are purely manual focus, generally have more glass, and are heavier and better designed. But in practical terms, what differences would you see if you took the same shot with a ZI lens and a comparable G lens? If anyone knows the answer, I'd be interested to hear.

BTW, I went to a camera shop in London today to look at the Zeiss Ikon (for the first time). A nice little camera, but I have to say I expected something -- well, more substantial and reassuring. I actually prefer the way my G2 feels in my hands!

 

[John]

I don't know that the ZI lenses are heavier, better designed, or have more glass? Most of them appear very similar to the G lenses with respect to lens formula, number of elements, sizes, f stops, coatings. It would be very interesting to read a comparo written by an optical engineer. 🙂 🙂

 

[JoeFriday]

I doubt there is a noticeable difference between the lenses of the two systems.. but there is clearly a difference in the camera bodies.. how they operate.. how they feel.. and the viewfinders are completely different

 

[Huck Finn]

Carl, I only own one of the new ZM lenses & I don't own any of the Contax G lenses. But judging by the MTF data, I do think that there is a difference in design philosophy between these two different lens systems. MTF data certainly has its limits of relevance, but you can tell a lot more in this circumstance than in most becasue first of all we're talking about MTF from the same company for both sets of lenses we're comparing & second, it's measured data so it relates to actual performance. Most published MTF data is calculated, so it's only theoretical, but Zeiss has always been different in this regard.

The most striking piece of information from the data is how much better the new ZM lenses are wide open than the G lenses. And this is consistent between all the comparable lenses. This makes sense because the Contax G system was designed primarily as an autofocus system & to be used in a style of photography that suits that design. The Zeiss Ikon is designed for classic rangefinder photography which often means low light work & therefore shooting at maximum aperture. In this regard, Zeiss has adopted the Leica philosophy of lens design. So, while I doubt that you'll see much difference at f/8, I bet that you will at f/2.

Another difference is the problem of finding direct matches. The G system has 6 primes, the ZM system has 7. No 25 in the G system.

- The 15/2.8 Distagon & the 16/8 Hologon are 2 radically different lenses despite the similar focal lenght. So really no comparison here.
- The ZM 85 is a stop faster than the G 90 & it uses floating elements with a non-linear coupling system. More sophisticated design, lenses not really comparable.
- The ZM 35/2 is a Biogon, the G 35/2 a Planar. Different fingerprints.
- The ZM "standard" lens is the classic 50 mm focal length, the G "standard" is 45. Not a big difference, but still different.

So, of the 6 primes, we are left only with 2 Biogons - 21/2.8 & 28/2.8 - to compare as a direct match. The other four are not comparable in one way or another. Two lenses is not much of a system comparison.

You've mentioned some of the differences in ergonomics, which is a big difference since I don't believe that you can focus the G lenses by hand. The G lenses have to be significantly lighter so that the AF motor can turn them easily. They are also more compact in length & 4 of the 6 uses a slightly bigger filter - significantly larger in the case of the 28. So, they are shorter, but wider at the front element in most cases.

I doubt that there will be much of a difference in most photographs, but there will be in some. The bottom line is that these are 2 distinctly different systems, designed to be used with two different approaches to photography. It shows in the optical design of the lenses where the ZM lenses are optimized for use at wide apertures & the G lenses for use at intermediate apertures. And it shows in the physical design of the lenses, whcih were created for two different kinds of ergonomics. There are also some hints that the ZM lenses were built with use on a future digital body in mind.

Huck

 

[sircarl]

Huck,

As I said in my original post, I realize these lenses are different in many ways, designed for different focusing systems and camera bodies. My question was, what practical difference would you see if you took pictures with "comparable" lenses? What I should have said, actually, was "lenses with the same -- or very similar -- focal lengths." I know that the 15/16 and 85/90 and 50/45 pairs, as well as both 35s, are comparing lenses that are differently constructed. But aside from a slightly different angle of view, how would that translate in an actual photo taken with each of those pairs? You mention better wide open performance in the ZI lenses, which makes sense. Some people have criticized the bokeh of a few of the G series lenses -- would the ZI lenses perform better in this respect? What about lens resolution at apertures other than the widest, contrast, tonal balance? These are the kinds of things I was wondering about.

Frank -- I don't think it was the weight of the G2's "motor" I was reacting to. In fact, I don't think it was weight at all, since the two cameras are pretty similar in weight (544g for the G2, 500g for the ZI). It's just an indefinable feeling of solidity and comfort that I felt was somewhat lacking when I held the ZI. But I realize that just may be me -- and my particular hands.

 

[jaap]

I think for film photography,wich is still the very very best way to photograph imo, the g-serie lens are the better ones. I'll try to explain in englisch. The ZM lenses are more a compromise for film applications. You can see this in the distance rear element filmbase.
The G lenses have rear elements wich point very far in the body. With the new ZM lenses this is impossible for futher digital camera's in mind. A digital body needs some space here.
Generally you see a bit more distortion for the ZM lenses compared to G lenses.
Both are fine lenses but for film potography I will take the G serie lenses def.
By the way the G lenses are also very good wide open!

 

[Huck Finn]

how would that translate in an actual photo taken with each of those pairs? You mention better wide open performance in the ZI lenses, which makes sense. Some people have criticized the bokeh of a few of the G series lenses -- would the ZI lenses perform better in this respect? What about lens resolution at apertures other than the widest, contrast, tonal balance? These are the kinds of things I was wondering about.

Carl, I don't have both lenses, so I can't answer the question. I doubt that there are too many people who have both although maybe someone will step forward. I would think that in terms of contrast, tonal balance, color saturation, the lenses would be very similar, given that they're designed by the same company in modern times & without Aspherics, using the same coatings, etc.

I was just trying to make the point that they're optimized for different styles of photography, hence better performance wide open with the ZM lenses. It's hard to get any better than the G lenses at intermediate apertures. ZM lenses seem to get universally positive acclaim fo their bokeh.

Huck

 

[Huck Finn]

I think for film photography,wich is still the very very best way to photograph imo, the g-serie lens are the better ones. I'll try to explain in englisch. The ZM lenses are more a compromise for film applications. You can see this in the distance rear element filmbase.
The G lenses have rear elements wich point very far in the body. With the new ZM lenses this is impossible for futher digital camera's in mind. A digital body needs some space here.
Generally you see a bit more distortion for the ZM lenses compared to G lenses.
Both are fine lenses but for film potography I will take the G serie lenses def.
By the way the G lenses are also very good wide open!

Jaap, others have also said that Zeiss made compromises so that the ZM lenses could be used for digital. We'd have to speak to a Zeiss engineer to find out if they compromised on optical quality to accomplish this. Otherwise, it's just specualtion. I do understand what you're saying about the protrusion of the G lenses into the body.

It is also true that restricting the lens designer to a compact baarrel also requires compromises in optical quality. As Zeiss demonstrated in the 1950's, the best way to achieve ultimate optical quality is to design a lens without size restrictions. However, this does not sell in the real world. Both lens lines were designed within certain restrictions & required certain compromises to achieve their goals.

I have no criticism of the G lenses & agree that they are very good wide open. They're just not as good as the ZM lenses or as a typicl Leica lens - at least as measured by the MTF data. My comment about wide open performance was not a criticism of the G lenses. It was just to say that their designs are optimized for performance at intermediate apertures - just as are most SLR lenses, only the G lenses do it better. This design choice makes a lot of sense for many applications. The G lenses are just about the best at these apertures. It's just not the choice for classic rangefinder photography as found in Leica lenses & now in the ZM lenses. The Contax G kit was sold with a flash for a reason. It's not as likely to be used for available light photgraphy.

Your comment that you see a bit more distortion for the ZM lenses is true only for the 28/2.8 & the 21/2.8. OTOH, you see more distortion in the 35/2 G lens than you do in the ZM 35. The 50 & 45 are identical in this regard, that is, no distortion. The 85 & the 90 also have similar amounts of distortion although in different directions. If anything, the G lens has slightly more distortion. In any case, discussing distortion in Zeiss lenses is really a quibble since they are generally very good in this regard. The Biogon designs, in particular, are much better than any alternative, as demonstrated in the distortion-free 35 Biogon vs the 35 Planar.

My 2 cents . . .

Huck

 

[Socke]

It's just not the choice for classic rangefinder photography as found in Leica lenses & now in the ZM lenses. The Contax G kit was sold with a flash for a reason. It's not as likely to be used for available light photgraphy.

Huck

I think so, too. Fastest G lenses are f2 but the bodies offer TTL flash with 1/125th and 1/200th.
The TLA200 flash is ideal for a light travel kit where you might need some fillflash, say at a beach.

The lenses are designed for AF, very light and with apertures providing enough FoV to cover AF inaccuracies. The 35 Planar may have been an afterthought, it was for me after all. I got it since the 28 was often too wide and the 45 too narrow for my liking and I changed lenses too often.
In tight quarters I still preferr the 28 over the 35 and with more space to position myself I prefer the 45. But on the streets, especialy in the narrow streets of old city centers, the 35 is what I use.

Today I wouldn't bother with Contax G and go straight to the ZI with a 35 Planar.

 

[sircarl]

Thanks everyone for your comments. I realize we're all sort of flying by the seat of our pants here, since no one seems (yet) to actually own lenses from both the G and ZI series lens lines which might enable you to make real-life comparisons. But I was hoping someone might have seen test data that could shed some light on these questions, which evidently some of you have. So thanks.

This wasn't entirely idle curiosity on my part. In the back of my mind I was wondering whether I should be considering changing from my Contax G system to a ZI system. Now before you all write in again to tell me how different these cameras are, I know, I know! As I said in my original post, I own a camera primarily for the quality of its lenses -- I find I can get used to almost any quirks in the camera itself, so long as they don't get in the way of the photography I like to do. That's why I never had any problems with some of the less-than-wonderful features of the G2, because the lenses are so fine (and the autofocus -- when it works properly, as it usually does -- lets me get shots no manual focus camera could have captured in time). Well, long story short, from what you all are telling me, it doesn't look like the differences between the G and the ZI lens lines are so compelling for me to make the switch.

 

[jaap]

The G2 can focus in complete darkness! I think it's very well suited for available light photography. The reason for the f2.0 and f2.8 lens design is to keep the size of the lenses moderate very important with rangefinder photography. The best equipmant for available light photography is imo a good SLR with high speed lenses. But that's just my experience other people may have other experiences

 

[awilder]

Having once owned a Contax G1 with a 45/2 Planar and a 50/2 ZM Planar briefly, I can say that the 45/2 was far sharper, in fact sharper than the current Summicron which says a lot. It's too bad the RF design of the passive AF wasn't reliable enough to take full advantage of the lens' incredible imaging potential. THe same goes for the 90/2.8 although it's equal to or a tad behind the current Elmarit-M primarily due to the camera's limitation on AF accuracy.

 

[tfelton]

I would like to jump in here for a second. I just sold my G2 system with the 28, 35, 45, and 90 lenses through this forum. I had previously bought the ZI with a 35mm. I enjoyed the G2 and the pictures were superb. I considered the 35mm my standard lens eventhough it's supposed to be the poorest of the lot.

However, the ZI fits my style of photography better than the G2. It's actually the type of camera that I grew up with (Contax IIa and Rollie TLR). I prefer to know my DOF.

 

[JSpicer]

For information on the Zeiss lenses for post-war cameras, go to the Zeiss website at http://www.zeiss.de/de/photo/home_e.nsf , click on Service & Maintenance, then on Download Center. There you will find links to current and historical Zeiss lens data, and to manuals and brochures. As for the new Zeiss ZM lenses, the Zeiss-Ikon web site has four chapters about the design of the new rangefinder camera and lenses. Plus, the recent editions of the Camera Lens Newsletter give more information.

In designing the ZM lenses, Zeiss had to increase the back focus of some lenses to meet Leica requirements so that the lenses would fit all Leica cameras. The remark about being digital camera ready did not imply a lowering of lens quality standards. Zeiss said that when digital sensors can accept light coming in at an oblique angle the way film can, then their lenses are ready. The lens tests conducted by Kornelius J. Müller of Zeiss show that the ZM lenses are capable of very high level imaging.