Earlier this year, I bought the 25 ZF but had a problem with undue softness encroahing well inside the edges that even f16 couldn't tame. I suspected the adaptor (Liliybox) but at the time did not have enough experience with these matters to be 100% sure it was the adaptor so returned the lens while still within its return period.
A photo you posted in another recent thread taken with your 50 ZF convinced me to try the M42 version rather than look for a used Contax version. The f5.6 photo in this thread only reinforces my impressions.
In general, the folks complaining about the CA, are they ones who have adapted the lenses to Canon or are they Nikon users?
I did however notice a touch of CA in the f1.4 image -- but it's not bad at all. Here is the crop with the marginal CA at f1.4. Look at the top of the roof: http://boncratious.info/ZF50mm14-crop1.jpg
What I did find interesting is the haze around some of the edges of the buildings on the left side of the image in the wide open image. Is this a function of how it handles OOF areas, or a function how performance falls toward the edges at larger apertures. I should try my c/y 50mm f1.4 to see if I get anything similar. Again, here is a crop identifying the area: http://boncratious.info/ZF50mm14-crop2.jpg
rfkiii wrote:
Earlier this year, I bought the 25 ZF but had a problem with undue softness encroahing well inside the edges that even f16 couldn't tame. I suspected the adaptor (Liliybox) but at the time did not have enough experience with these matters to be 100% sure it was the adaptor so returned the lens while still within its return period.
The ZF 25mm is a curious beast. In some ways it is a stellar performer in other ways it seems to fall flat. In some respects, according to communication from Zeiss, its design was done to optimize performance for an APS-c sensor -- not full frame even though the lens covers full frame. Further, they make a point of the making the lens focus closely, yet seem to do little to optimize its performance at close focus (e.g. no floating element) with Zeiss suggesting it's use at close focus would be for "atmosphere" (which to me is a cop-out rationalization for bad performance). Zeiss could have done a lot more with this lens. I was originally quite interested in this lens, but no longer as it ultimately disappoints.
Here is the relevant text of the comments I received from Zeiss on the ZF 25mm:
In spite of the close minimum focus distance the lens has no floating elements. So the close focus is not intended to be used for copy work. It is for three-dimensional subjects, where there is a main part in the centre and the rest is just "atmosphere". It allows very dynamic pictures of small things, very different from the distant view of typical macro lenses. And in this kind of subjects field curvature is no issue. Testing the lens with flat targets reveals the typical weaknesses, but it is far away from many practical applications.
The close focus capability is also a kind of historical footnote, since the "great grandfather" of this lens for the Contarex had the same feature. The design is of course new, and we particularly looked for improved field flatness within the APS area.
None of my various 50's show bad CA and indeed I see only what Lotusm50 has shown in your examples. I doubt you will see anything too bad with this 50, but in every case where I have experienced a CA issue, these conditions existed:
1)A wide angle lens was used of 28mm or wider on full frame 5D.
2)The shot was taken in shade or open shade with more intricate backlit objects/subject such as tree branches and leaves.
3)Exposure bracketing was used so that in at least a few of the shots, the backlit highlights were not blown out to avoid sensor bloom. Using Fill Light in Raw conversion via Lightroom OR any other Raw conversion tools in C1Pro to bring up the shadows in these shots during conversion would still result in what looked like terrible CA on the edges of the leaves or branches.
My conclusion is that most who see similar type issues as above in similar type lighting situations are really just pushing the images too far in the Raw conversion and majorly accentuating the little CA of the lens which may exist. But this would be the torture test to use I think.
Lotusm50 wrote:
I should try my c/y 50mm f1.4 to see if I get anything similar.
My shot was exposed to the right, if you understand what I mean and this is quite important with fast lenses. Also I pushed up the dpp sharpening tool to 7 wide open to show off possible CA. Looking on a unprocessed image the 1.4 photo would look soft, though there is still plenty of resolution. Just a note if you want to get similar results with your c/y lens
I would not shoot landscape wide open and I would certainly not sharpen my images that much, this was more to give people an idea of what the lens can do and how bad CA really was.
Regarding that purple edge on top of the metal roof in the close-up There are a few theories as to what to call it. Some refer to it as axial color longitudinal chromatic aberration, others call it sensor bloom, some refer to it as bi-refringence. It is typically present in areas of super bright white when you shoot at or nearly wide open.
Whatever you call it, whatever causes it, it happens with any fast lens at wide open, Canon or Zeiss.
I do think that there are some sensor issues contributing to what most call CA beyond simply Sensor Bloom as a result of overexposure, at least for wide angle lenses.
I have read about terrible CA with the Canon 85 1.8 and I have yet to see it with my copy. Wide Open with heavy backlighting I suspect I would see it wide open as JJlphoto mentions.
CA is still present at f2.8 in your sample images . . . http://www.16-9.net/zf50ca.jpg
It's not terrible: most 50mm are OK in this regard.
I know he's not popular in these parts but the much-maligned Ken Rockwell has demonstrated pretty conclusively that the ZF50 doesn't handle CA as well as most Nikon 50mm primes. He really pushed the boat out in his 50mm comparisons: http://www.kenrockwell.com/nikon/50-comparison/lca.htm
Given the ease with which it can be fixed – non deleteriously – it's not really a problem when the lens has outstanding virtues in other areas. I'll also revisit my Contax 50/1.4 looking for CA. The ZF certainly looks better resolved wide open than the CY version. Can anyone comment on the N 50mm?
The ZF25 is an oddity: it's clearly only optimised for an APS sensor: I remember a vigorous debate on the subject after this review appeared. Great close focusing, but lousy close range performance? Covers full frame, but only sharp in the middle? What were they thinking?
hubsand wrote:
The ZF certainly looks better resolved wide open than the CY version. Can anyone comment on the N 50mm?
The conversion for the Zeiss N 50mm Planar is not yet available. There are many of us patiently waiting.
hubsand wrote:
The ZF25 is an oddity: it's clearly only optimised for an APS sensor: I remember a vigorous debate on the subject after this review appeared. Great close focusing, but lousy close range performance? Covers full frame, but only sharp in the middle? What were they thinking?
"What were they thinking?" Indeed. And that pretty much summed up my unrestrained and comprehensive response back to Zeiss.
What it does, however, refute is the oft heard comment that since Zeiss was making all these full frame lenses in the Nikon F mount, Nikon MUST be coming out with a camera with a full frame sensor -- as if Zeiss was in on it in some way. I suppose not if Zeiss is optimizing at least some of these lenses for APS sensors.
At f/1.4, I think this level of CA is still acceptable though. Even a leica 50/1.4 E60 exhibit signs of CA more seriously wide open. However, 50 lux is much more contrasy than ZF.
Lotusm50 wrote:
What I did find interesting is the haze around some of the edges of the buildings...
This is exactly what I see with the 35-70/3.4 wide open as well and is the main reason I've been thinking of switching to the Leica 35-70/4. At first I thought it was the bokeh kicking in, but bokeh shouldn't be washing out colour as severely as the wide open sample Andi posted shows.
Lotusm50 wrote:
What it does, however, refute is the oft heard comment that since Zeiss was making all these full frame lenses in the Nikon F mount, Nikon MUST be coming out with a camera with a full frame sensor -- as if Zeiss was in on it in some way. I suppose not if Zeiss is optimizing at least some of these lenses for APS sensors.
I certainly hope Zeiss isn't optimizing FF lenses for APS sensors, which seems counter-intuitive to what Zeiss is as a company, i.e. putting out a product that is intentionally weak in some aspect. Making APS only lenses would seem to me to be more how they would go about cutting R&D or manufacturing costs.
There must be something in Camera Lens News about their rationale for going with FF lenses for all these APS mounts (Nikon, Pentax, etc.) and I think it's because there are still people out there who Zeiss feel are going to use these lenses on film bodies.
StevenPA wrote:
I certainly hope Zeiss isn't optimizing FF lenses for APS sensors, which seems counter-intuitive to what Zeiss is as a company, i.e. putting out a product that is intentionally weak in some aspect. Making APS only lenses would seem to me to be more how they would go about cutting R&D or manufacturing costs.
Making them full frame but optimizing for only APS is sort of neither here nor there. They wind up being more expensive than an APS-only lens, but disappointing on a full camera.
StevenPA wrote:
There must be something in Camera Lens News about their rationale for going with FF lenses for all these APS mounts (Nikon, Pentax, etc.) and I think it's because there are still people out there who Zeiss feel are going to use these lenses on film bodies.
They will tell it is to meet the needs of existing film camera users. In Zeiss' marketing materials for their lenses at least, film is far from dead and is the only medium that can capture the full performance of their lenses. Internally at Zeiss, I suspect the tenor of the conversation is a bit different.
