Re: ZE 50/2 and 100/2 Makro-Planar charts
Quote:
Originally Posted by Trondster
Bokeh fringing, Bokeh CA, Longitudinal CA, Axial CA - are all words for the same phenomenon.
I guess my point was that those terms are all used interchangeably - but that doesn't mean that such use is correct. There are lots of people who say or write the word, 'irregardless,' but that doesn't make it a word, nor does the common use of the word 'data' as a singular noun (e.g., the data is correct) make that usage correct - data are plural (except when used as the proper name of a Star Trek character, of course ;).
The distinction becomes important in other types of lens applications, for example in confocal microscopy where out-of-focus light is eliminated by a pinhole in the optical path, but axial CA can still be present if the lens is not sufficiently corrected. That's why the lenses on my confocals are fluorite or planar apochromatic lenses corrected for SA and CA in at least 3 and usually 4 colors - (and many of them cost well into the 5-figure range).
Quote:
Originally Posted by Trondster
I'd rather call the fringing on the Nikkor lenses longitudinal CA due to missed focus....You would be able to see "bokeh fringing" or "Longitudinal CA" all over a flat chart, if theentirechart was out of focus - as I believe we see in the crops for the Nikkor 135/2.
The thing I have trouble reconciling is that despite the purple fringing, the chart looks focused and sharp. Other Nikon fast primes (50/1.4, 85/1.4, 85/1.8) exhibit similar fringing - not just the 135/2. So there are a few possibilities:
- Bryan is intentionally trying to make these lenses look bad.
- Bryan is not very good at focusing on his test chart.
- There is some unidentified step in the testing workflow that is introducing an artifact into the results.
- The fringing is a 'feature' of some Nikon lenses.
I don't buy the first two at all. The third one is certainly possible. The fourth one is also possible - bear in mind that pure black on pure white illuminated by four SB-900 or 580EX II strobes generates more contrast than most 'real-world' shots.
Re: ZE 50/2 and 100/2 Makro-Planar charts
The poor results regarding several Nikkor lenses are easily explained. All the Nikkor images were batch shot and hastily uploaded into the database, to provide a large database of Nikon-related images. There was probably not time to check every image and reshoot if necessary.
When the time comes to write the reviews proper, the ISO crops will quite certainly be reshot for the ones being out of focus or imperfect in any other way.
And no, they are not completely blurry, they are nudged just that little bit out of focus, causing a color cast. Check my example links above for the Photozone reviews - the lines with color cast closest to the focus plane are not necessarily that blurry - a bit blurry, but with quite the color.
Try it yourself - shoot a perfectly flat black and white chart with an 85L or similar, shooting using manual focus and focus stepping - you'll probably end up with both green, black and purple charts.
Re: ZE 50/2 and 100/2 Makro-Planar charts
Since the aforementioned charts have been taken down as of this writing, I am withholding further speculation on the matter until further clarification is provided.
As to the chromatic aberrations in the Nikon charts, we have already discussed this issue to some extent in other threads. At this time I do not have an explanation for the purple fringing, but I would be highly doubtful that this could be caused by flawed or sloppy methodology; and I think it is a bit unbecoming to suspect that as the cause, without any evidence to support such a claim. That is to say, if you are going to accuse Bryan of "hasty uploading" of test results on his own site, you better have a way to back it up, because I find that accusation to be distasteful.
In any case, what we DO know is that there must be some kind of automatic lateral CA correction taking place, because NONE of the Nikkor results show any lateral color whatsoever. That is an obvious impossibility. So the likelihood of these lenses needing retesting is high, in my opinion--regardless of any axial color issues.
Finally, I hope that everyone can step back and refrain from jumping to conclusions about the test charts or make sweeping generalizations about how some brands are better than others, and try to be a bit more objective about the results themselves.
Re: ZE 50/2 and 100/2 Makro-Planar charts
..And the charts are back up - with significantly sharper results in the center. I'd say that the Makro-Planar 2/50 still soundly trounce the comparable EF lenses in the corners at f/2.
It depends on the priorities, I guess - EF 50/1.2L is optimized for performance wide open, EF 50/1.4 has a large aperture and fantastic performance stopped down, at an attractive price point, and Makro-Planar 2/50 has very good performance at the cost of being slower, more expensive and manual focus only, and with an insanely long focus throw.
Makro-Planar has in my opinion two weaknesses - neither of which are shown here: It has a lot of LoCA, and the focus plane is curved - I have not performed any systematic testing, but it seems that this effect is more pronounced at longer distances - it seems the lens is optimized to excel at close range.
So - which is "better"? It depends on your usage - they all have strengths and weaknesses and excel in their own areas - what is important for you? :)
