innerimager Posted February 13, 2007 Share #1 Â Posted February 13, 2007 Advertisement (gone after registration) In this albeit extreme condition, here is a 100% crop showing chromatic aberration. I would expect that this kind of very bright light with extreme contrast would be the kind of thing the lens would be good at controlling. Am I expecting too much? (Iso 1600 with an RD-1) thanks...Peter Link to post Share on other sites More sharing options...
Advertisement Posted February 13, 2007 Posted February 13, 2007 Hi innerimager, Take a look here Noctilux CA. I'm sure you'll find what you were looking for!
LJL Posted February 13, 2007 Share #2 Â Posted February 13, 2007 Peter, Not sure if that is CA or really just something many know as "purple fringing". The PF thing is more common to digital. It is the result of the sensor photosite in the darker area being flooded with energy spillover from the blown out area, as I understand it. Perhaps others can better explain. I have seen this on many lenses subjected to such a dramatic contrast of blown out area adjacent to almost black areas. I used to think that some lenses were more susceptible than others, and that may be the case if they are also more prone to CA. I just know that I have seen this manifest itself with almost every lens I have used on my Canon 1-series cameras, and a few times recently on the M8. I do think it is more sensor related than lens related. Â LJ Link to post Share on other sites More sharing options...
innerimager Posted February 13, 2007 Author Share #3 Â Posted February 13, 2007 thanks LJ- Indeed I also suspect this may be more sensor related. I'll try and torture the nocti on my M8 in similar fashion and see how things look compared to the RD-1. best....Peter Link to post Share on other sites More sharing options...
LJL Posted February 13, 2007 Share #4  Posted February 13, 2007 Peter, Here is a refernce that describes "purple fringing" as a form of CA at the microlens level.  Chromatic Aberration: Optical: Glossary: Learn: Digital Photography Review  LJ Link to post Share on other sites More sharing options...
dhoelscher Posted February 13, 2007 Share #5 Â Posted February 13, 2007 I ...I would expect that this kind of very bright light with extreme contrast would be the kind of thing the lens would be good at controlling. ... Â Take a look at the owner's manual supplied with the Noct .... they mention that the "chromatic effects" start to go away at f/4. Â I'm a guessing that these "personality" effects are something that Leica feels is "in character" for this lens. Â DH Link to post Share on other sites More sharing options...
bradhusick Posted February 13, 2007 Share #6 Â Posted February 13, 2007 Some of this is correctible in ACR with their CA corrections and reducing some of the purple and blue saturation. Adjusted, then original: Link to post Share on other sites More sharing options...
innerimager Posted February 13, 2007 Author Share #7 Â Posted February 13, 2007 Advertisement (gone after registration) yes, definitely correctible, both with CA correction directly in various raw processors, or a simple select and desaturate. Not to mention it would take a huge print to even see it. Just curious, and I appreciate all the responses very much. best.....Peter Link to post Share on other sites More sharing options...
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