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Archive 2012 · Contax Zeiss 28mm f2 and ZE/ZF
  
 
paulcurtis
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p.1 #1 · Contax Zeiss 28mm f2 and ZE/ZF


I'm looking for someone who has one of these lenses to confirm whether my recently acquired version is comparable in quality. I'd also like to know whether anyone who has the ZE/ZF version see's the same kind of wide open performance.

I picked the worst subjects i could. Bright sunny daylight against a flat field (well, basically a brick wall)

There's quite a bit of haze across the f2 (this obviously goes away when stopping down) and a lot of aberration around the high contrast areas.

http://www.flickr.com/photos/inventome/7644396208/

http://www.flickr.com/photos/inventome/7644394626/

Those are 2 100% crops (flickr has the originals too).

Does anyone have anything comparable, do these look okay? Wide open it seems a bit hazy to me but i have very little to compare too.

many thanks
paul



Jul 25, 2012 at 04:22 PM
AhamB
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p.1 #2 · Contax Zeiss 28mm f2 and ZE/ZF


Looks perfectly fine to me for 100% crops at f/2. I'd advise to try it for some acual shots where you make use of the widest aperture (unless you typically shoot brick walls).


Jul 25, 2012 at 06:08 PM
carstenw
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p.1 #3 · Contax Zeiss 28mm f2 and ZE/ZF


Those look quite okay to me. My ZF.2 is perhaps a bit sharper wide open, but you have to expect some kind of improvement over that many years, probably mostly in the coatings.


Jul 25, 2012 at 06:19 PM
formula4speed
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p.1 #4 · Contax Zeiss 28mm f2 and ZE/ZF


I'd say my 28 ZE is a bit sharper than that at f/2. Aberration control is definitely not a strong point for the 28 ZE though, so I wouldn't expect much if any improvement there.


Jul 25, 2012 at 07:39 PM
paulcurtis
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p.1 #5 · Contax Zeiss 28mm f2 and ZE/ZF


That's good to know, however i think the lens has been dropped at one point, the focus is a little stiff and if i look at the collar at the top (the bit that moves in and out) it's ever so slightly angled. Now this part seems to be where the filters go because the front element is on a helicoid inside that. The focus across the field seems fine. So the lens inside must be aligned okay - it's just there's a little resistance when focusing. I'm comparing this to my other CZ Zeisses so i know it's slightly off.

Anyone heard of issues with the front collar?

I tested a ZF.2 50mm against my CZ 50 f1.4 and i found the ZF slightly sharper but actually had more chromatic aberration. I assume a different trade off, sharpness against correction.

many thanks for the comments so far
cheers
paul



Jul 25, 2012 at 07:40 PM
AhamB
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p.1 #6 · Contax Zeiss 28mm f2 and ZE/ZF


paulcurtis wrote:
I tested a ZF.2 50mm against my CZ 50 f1.4 and i found the ZF slightly sharper but actually had more chromatic aberration. I assume a different trade off, sharpness against correction.


Blue = Z*, black = Contax.













There are some people who have reported that the Z* has more spherical aberration (haze) wide open though.



Jul 25, 2012 at 08:00 PM
Keith B.
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p.1 #7 · Contax Zeiss 28mm f2 and ZE/ZF


carstenw wrote:
Those look quite okay to me. My ZF.2 is perhaps a bit sharper wide open, but you have to expect some kind of improvement over that many years, probably mostly in the coatings.


Having owned the Contax 28/2 back in the film days, and now the ZF 28/2, my estimation is that the current one is better wide open by a small but noticeable margin. The central area is useable wide open on the new one, but it was a little blurry on the old one. Blurry, not soft.



Jul 26, 2012 at 04:03 AM
paulcurtis
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p.1 #8 · Contax Zeiss 28mm f2 and ZE/ZF


I'm talking to a Lens tech about it, he thinks some of the elements are out because the images are too soft. So i'll explore that option i think. It's difficult to find CZ lenses these days - always open to recommendations about where to look.

On the CZ vs ZF i did a simple side by side with the 50 f1.4

http://www.flickr.com/photos/inventome/7649390790/

http://www.flickr.com/photos/inventome/7649390348/in/photostream/

in this particular case i found the ZF a bit sharper but at the expense of more fringing. Everything was identical in the set up just the lenses. The same result was true at different ranges to a lesser degree. Very obvious close up here.

cheers
Paul



Jul 26, 2012 at 11:08 AM
AhamB
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p.1 #9 · Contax Zeiss 28mm f2 and ZE/ZF


What was the focus point in this last test? The box looks sharper in the CZ image but the metal parts (hinges?) look sharper in the ZF image. There are probably some differences in field curvature complicatating the comparison.


Jul 26, 2012 at 12:21 PM
 

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paulcurtis
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p.1 #10 · Contax Zeiss 28mm f2 and ZE/ZF


AhamB wrote:
What was the focus point in this last test? The box looks sharper in the CZ image but the metal parts (hinges?) look sharper in the ZF image. There are probably some differences in field curvature complicatating the comparison.


Could be, the focus was live view on the zeiss logo in both cases. I'd find it difficult to see field curvature being that different when the basic lens design is the same. I think the ZF has different coatings. Of course Zeiss just lump it all under T* and it would be great if they differentiated a bit.

The ZF was slightly cooler overall, light transmission was pretty much the same. I just found the ZF to show more aberrations. The magenta bloom i always though was sensor generated but in this case same sensor. The ZF is sharper, wide open anyway. I found the CZ a little less precise, which for me i think i prefer.

I'd love to find someone locally in Kent with ZFs to compare. I've agonised over whether i should sell up the CZ and go down ZE/ZF. These are primarily used for filming, so i'm getting the declicked etc,. but it's always a risk with old lenses that have histories you cannot confirm. Also there are some ZE/ZF lenses i'd really like - the 50 macro planar for example and the 25 f2.

ALthough then i think i'm just being greedy...

If you want to see some really weird results i should show the comparison between a 28mm f2.8 distagon and a Zeiss ZA 24-70 f2.8 zoom. The Zoom has less depth of field, noticeably so.

thanks
Paul



Jul 27, 2012 at 09:07 AM
Toothwalker
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p.1 #11 · Contax Zeiss 28mm f2 and ZE/ZF


paulcurtis wrote:
I just found the ZF to show more aberrations. The magenta bloom i always though was sensor generated but in this case same sensor. The ZF is sharper, wide open anyway..


How can the ZF simultaneously show more aberrations and be sharper? In the absence of motion blur and misfocusing, aberrations are the only mechanism left to affect the sharpness of a lens. Certainly at f/1.4, where diffraction is of no importance. Anyhow, my findings are different. (Edit: different concerning the sharpness, not the aberration part )

The ZF is basically the same design, but adapted to environmentally friendly glass types. Zeiss had no problems with selecting the most suitable glass types 40 years ago, and in retrospect I would not expect the ZF to perform as well as the Y/C version.

To my knowledge there is no sensor that produces a magenta bloom. It is always the lens.



Jul 27, 2012 at 04:13 PM
paulcurtis
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p.1 #12 · Contax Zeiss 28mm f2 and ZE/ZF


Toothwalker wrote:
How can the ZF simultaneously show more aberrations and be sharper? In the absence of motion blur and misfocusing, aberrations are the only mechanism left to affect the sharpness of a lens.

The ZF is basically the same design, but adapted to environmentally friendly glass types. Zeiss had no problems with selecting the most suitable glass types 40 years ago, and in retrospect I would not expect the ZF to perform as well as the Y/C version.

To my knowledge there is no sensor that produces a magenta bloom. It is always the lens.


AFAIK sharpness is usually a trade off between LoCA aberrations and detail. But in this case as the lens designs are pretty much the same, i assume the coatings are the main difference. Perhaps when i say aberration i mean the fringing on high contrast edges (usually purple but can be green depending on whether it's in front or behind the focus point), i'm pretty sure this is LoCA. But i do remember seeing several tests with the same lens on different sensors and in some cases you do get sensor bloom which is always magenta - of course it's not the sensor but a lens/sensor combination.

Either way i saw higher degree of magenta fringing with the ZF than the CZ at the same given focus point. Pretty much the same as you saw on your other thread.

It could be sample variation also, i might have an especially good CZ or had a poor ZF.

cheers
paul



Jul 31, 2012 at 11:45 AM
AhamB
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p.1 #13 · Contax Zeiss 28mm f2 and ZE/ZF


I believe that purple fringing means that red and blue are not in focus but green is. What you're perhaps thinking is that old lenses with a lot of spherical aberration don't show much colored fringing, but that's because the colors are blended in a white haze (hidden by low contrast).


Jul 31, 2012 at 01:16 PM
Keith B.
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p.1 #14 · Contax Zeiss 28mm f2 and ZE/ZF


Toothwalker wrote:
The ZF is basically the same design, but adapted to environmentally friendly glass types. Zeiss had no problems with selecting the most suitable glass types 40 years ago, and in retrospect I would not expect the ZF to perform as well as the Y/C version.


The ZF is certainly from the same family of designs, but in the Zeiss-supplied schematics every element is different.
The ZF/ZEs are built heavier-duty as well. Many observed, back in the Contax days, that you could freeze the focus barrel rotation by squeezing hard on it while trying to rotate. Obviously, during the Olympus OM-1 "Everything must be miniaturized" fad/era, Zeiss went a little too far in slimming down some of the Contax lenses.



Jul 31, 2012 at 05:53 PM
Toothwalker
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p.1 #15 · Contax Zeiss 28mm f2 and ZE/ZF


Keith B. wrote:
The ZF is certainly from the same family of designs, but in the Zeiss-supplied schematics every element is different. The ZF/ZEs are built heavier-duty as well. Many observed, back in the Contax days, that you could freeze the focus barrel rotation by squeezing hard on it while trying to rotate. Obviously, during the Olympus OM-1 "Everything must be miniaturized" fad/era, Zeiss went a little too far in slimming down some of the Contax lenses.


You can freeze the ZF/ZE barrel rotation too. You just need to squeeze a bit harder.

The new line feels mechanically more robust, but only time will tell for sure. It's a pity that the optics are a step back, in some cases.



Aug 01, 2012 at 03:38 PM
edwardkaraa
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p.1 #16 · Contax Zeiss 28mm f2 and ZE/ZF


Toothwalker wrote:
You can freeze the ZF/ZE barrel rotation too. You just need to squeeze a bit harder.

The new line feels mechanically more robust, but only time will tell for sure. It's a pity that the optics are a step back, in some cases.


+1



Aug 01, 2012 at 03:44 PM
Toothwalker
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p.1 #17 · Contax Zeiss 28mm f2 and ZE/ZF


paulcurtis wrote:
AFAIK sharpness is usually a trade off between LoCA aberrations and detail. But in this case as the lens designs are pretty much the same, i assume the coatings are the main difference. Perhaps when i say aberration i mean the fringing on high contrast edges (usually purple but can be green depending on whether it's in front or behind the focus point), i'm pretty sure this is LoCA.


If it is in front or behind the focus point, you should be careful with calling it an aberration. An aberration such as longitudinal chromatic aberration is quantified with respect of the plane of sharp focus - or at least the point that is supposed to be sharp. A statement like "The ZF shows more aberrations and is sharper" is a contradictio in terminis.

But i do remember seeing several tests with the same lens on different sensors and in some cases you do get sensor bloom which is always magenta - of course it's not the sensor but a lens/sensor combination.


It is the combination of a lens with chromatic aberration and a sensor with elevated sensitivity to the the violet (and maybe far red) ends of the spectrum that is to blame. Purple fringing is no sensor bloom and would not occur with a perfect lens.


Either way i saw higher degree of magenta fringing with the ZF than the CZ at the same given focus point.


That is very much possible.


Pretty much the same as you saw on your other thread.
It could be sample variation also, i might have an especially good CZ or had a poor ZF.


In that case my ZE is also especially poor.








Aug 01, 2012 at 04:00 PM





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