I'm afraid you were looking at a too small detail. Let's look at the top of the rock, where the water divides into two streams. The left stream is purplish and the right one is greenish. And the rock behind them turns its colour too.
vdo1 wrote:
I'm afraid you were looking at a too small detail. Let's look at the top of the rock, where the water divides into two streams. The left stream is purplish and the right one is greenish. And the rock behind them turns its colour too.
vdo1 wrote:
I'm afraid you were looking at a too small detail. Let's look at the top of the rock, where the water divides into two streams. The left stream is purplish and the right one is greenish. And the rock behind them turns its colour too.
Exactly my thought. There is obvious LoCA in the waterfall image.
@Phillip Reeve: Did you get around to compare it to the CV 40/1.2 @F2?
vdo1 wrote:
I'm afraid you were looking at a too small detail. Let's look at the top of the rock, where the water divides into two streams. The left stream is purplish and the right one is greenish. And the rock behind them turns its colour too.
+1 Not difficult to spot, just using my phone.
Maybe you can take a picture of the fountain used to check correction on the 65? Would make for a good comparison.
Although not perfect, the 50/2 APO is well corrected for axial CA. Not at same level as Voigtlander 65/2 or 110/2.5 but still way above average and perhaps APO level for a 50mm lens.
I think that is the correct interpretation.
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Fred Miranda wrote:
Although not perfect, the 50/2 APO is well corrected for axial CA. Not at same level as Voigtlander 65/2 or 110/2.5 but still way above average and perhaps APO level for a 50mm lens.
1. I've posted at p27#15 what I am seeing - what appears to be LoCA but on closer inspection is something very faint, residual. Bear in mind that perfection won't exist, and APO is harder in shorter FLs.
Throw in secondary LoCA and be aware that APO lenses tend to make visible minor second order aberrations that lesser lenses won't show. I've not seen any fringing in this one. Interesting that Leica use s/w to remove fringing in the SL APO lenses and maintain they have no LoCA at all. Maybe that is a design trade-off.
Cameralabs put the Otus 55 through its LoCA tests, and reported on these 'brutal tests for lenses: the sun reflecting on water. This produces extreme specular highlights which mercilessly reveal longitudinal CAs, purple fringing and coma. The Zeiss exhibits clearly less of these aberrations than the Nikon 58/1.4G although it is not free of them.'
The images on those pages are not flattering, and are worse than I've been able to provoke from the Voigt 50/2. The Otus 55 also has far busier OOF bokeh balls which can fringe green.
Steve Huff provides examples of rather unsettled bokeh in the 50AA-M:
2. In other, much more important image-centric respects, the 50/2 AL behaves like an APO lens:
deep, rich and convincing micro-contrast, exquisite upper tonal range control, tremendous colour depiction, soft smooth bokeh coming off a very high plane contrast. These are the things that make the lens so appealing. From Ming Tein reviewing the Leica 50/2 Summicron-M APO (which appears to have less polished bokeh than the AL) :
"I didn’t see any lateral chromatic aberration in any of the 500 or so test images I shots with this lens, many of then deliberately framed and composed to provoke it. There is a tiny bit of spherochromatism (bokeh fringing), but it too is fairly minor. The apochromatic nature of the lens is actually given away more by its micro contrast structure than edge CA/ fringing; let me explain why.
Non apochromatic lenses focus different wavelengths of light at slightly different distances; if you cut the sensor plane through this, you’ll land up with some wavelengths being focused and others not; this is why edges aren’t perfectly defined, and why the vast majority of lenses have trouble reproducing extremely fine detail structures. The 50 AA has no such issues, by the way."
and Victor Pavlevic:
'Because chromatic aberration is however caused by different focus planes for different color waves (either in planar or axial direction), by removing color we actually leave the monochromatic (luminescence) component.
Therefore edges with color aberration will never be visually as sharp as edges optically corrected, even if we remove visible color deviation. This little extra edge contrast, might influence resulting image appearance in some situation. It is one of the main reason why I still see Otus images being superior in subject isolation, despite Otus bokeh having lot of space for improvement.'
[This page below also has an excellent depiction of muted but easily visible LoCA in the Batis and Loxia 85s compared to an APO lens, in the form of the Otus 85.]
philip_pj wrote:
1. I've posted at p27#15 what I am seeing - what appears to be LoCA but on closer inspection is something very faint, residual. Bear in mind that perfection won't exist, and APO is harder in shorter FLs.
Yes, perfection won't exist, so much is clear. However, CV has shown that at a similar focal length, much better correction is possible. I just can't imagine that those 15mm make all the difference.
Also, I don't think we are splitting hairs here. I can clearly see the aberration on images from a low-res sensor (24 megapixel). Things would be different if the aberration only manifests on e.g. the A7rIV.
Many people have stated that the 65AL is better corrected than the 50AL. I also think that is the case but I would really like to see a direct comparison because I think the difference is smaller than many think. The 65AL isn't perfectly corrected. Have a look at this image for example: Voigtlander_65mmF2_APO_Macro-20 by Phillip Reeve Data, on Flickr
100% crop
But when you compare it to for example the 1.8/55 does it become apparent how much better the AL is corrected. Sony FE 1.8/55 | f/1.8 by Phillip Reeve Data, on Flickr
And APO doesn't mean that a lens is perfectly corrected for any CA. To quote Wikipedia: "Apochromatic lenses are designed to bring three wavelengths (typically red, green, and blue) into focus in the same plane. The residual color error (secondary spectrum) can be up to an order of magnitude less than for an achromatic lens of equivalent aperture and focal length."
And yes, there are longer or slower lenses better corrected but also the Otus 55 and Leica AA50 are not perfectly corrected for CA. So the AL50's performance is among the best in class and significantly better than most.
More important to me though is if CA has an effect on my images and here I have to answer with no. Yes, if you search for it you see traces of CA in some images but unless you are really sensitive to CA I can't see how you could take issue with such an performance:
(Another 100% crop from the image above)
