[stoppingdown]

Gents,
 
as I told you some time ago, I'm concentrating on flower photography (still for a couple of weeks; then I hope to resume some journey and do landscapes again). In particular, I'm using four non-macro lenses with macro adds-on: close-up lenses with the SEL70200G and focusing helicoid built into the adapter with a Nikkor 50mm Æ’/1.8D AF, a Helios 44-2, and a Trioplan adapted to E-mount.
 
In general, I'm enjoying the thing a lot, and there are a number of things that I'm practicing, that are beyond the point of optical quality: picking the best flowers, studying the light, tyring to pre-visualise the shot, critically focusing, etc... I think I'm learning lots of things. In particular, I'm also comparing the different bokeh that I can achieve even with lenses of similar focal (such as the Nikkor and the Helios above mentioned).
 
Now I've started looking at the optical quality too. I'm practicing especially in wide-open shots, where the overall look of the photo doesn't require a high resolution (even though I must say that there is a good amount of sharpness on the centre of all the lenses, the Nikkor 50mm in particular). One of the potential problems, instead, are aberrations that are induced by the focusing helicoid, since the lens is forced to work outside of the settings for which its design has been optimised. This happens, clearly, especially with white flowers and dark backgrounds, and worsened when shooting with backlight.
 
In this context, I have some things to ask you. First, whether I'm correctly interpreting as optical defects some details in the samples below (the #1 and #2 are extreme crops).
 
In the first photo (Nikkor) I see green fringing on the rightmost petal (it seems confirmed to be fringing by the fact that an almost identical photo, with the focal plane just shifted a bit, doesn't show any trace of it). On the leftmost petal and the one at the bottom I see purple colour, but not at the border. This flower (Anemonoides trifolia) is supposed to be fully white, but I think this doesn't exclude that some can have traces of purple (I'll ask a flower expert anyway). In your opinion, is this a lens defect?
 
The second sample (Helios), on the other hand, shows purple and green fringing in all the borders of the flower. I think these are clearly optical defects. In this specific case they are probably amplified by the fact that I had to boost saturation a lot here (+40), way more than I usually do, because - I think - of the backlight that produced de-saturated colours out of the camera. In fact, I had to de-saturate yellow as the stamens, after boosing the global saturation, appeared full yellow, while they should be white as in the former photo (same flower species).
 
First question: would a specific macro lens, native E-mount, such as the SEL50M28 totally or substantially better than this? I presume so, but I can't tell.
 
Second question: I've tried to fix the problem in Lightroom by operating with the Lens Correction / Manual / Defringe / Amount (purple and green) sliders. But they seem almost uneffective. I basically don't know the exact way in which the two additional sliders "Purple hue" and "Green hue" work; would they be useful for improving the thing?
 
At the moment I'm dealing with the problem by applying local brushes with desaturation (clearly in the samples I posted I disabled my corrections).
 
All in all, it's not a great problem. I'm attaching one of the full-sizes photos for an evaluation of the final result, and the aberration effect is not jumping to the eyes. The next major buy will be the A6300, so there's no high priority for a native macro lens (*), but... if it makes sense, it could be budgeted for the end of the year.
 
(*) The 50mm Sony macro lens is a 2.8 max. aperture, while the Nikkor and Helios 44-2 are one stop brighter... While it's hard to make a macro good photo at full aperture, in some chances I like what I see. Not sure I could reproduce the same bokeh with the SEL50M28.
 
Thanks.