A1 and Chromatic Aberration...good news, bad news.

Dennis Wood

Dennis Wood

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I posted up some test footage of the A1 and Brevis35 yesterday and got lots of comments on the chromatic abberration seen in one part. Well a 30 second test, and guess what...it's the cam! It may not be CA as usually that's magenta..but if not, what is it?

The bad news is that at f2.4 it's awful. The good news is that at f4.8 it goes away.

The clip.
 
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So--there's awful chromatic aberration at any focal length when you're more open than 4.8? Isn't that incredibly bad news for anyone who wants to throw the background out of focus in sit-down interviews (unless they're done in a huge room)?
 
thoughtsauce said:
So--there's awful chromatic aberration at any focal length when you're more open than 4.8? Isn't that incredibly bad news for anyone who wants to throw the background out of focus in sit-down interviews (unless they're done in a huge room)?
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I have not seen this occur on A1 alone or A1 with an m2. Whatever issue is occuring has either to do with two things: Guskers settings, or the brevis stuck on the end.
 
Well, here it is, bare cam.

It goes away with NR1 off, and exposure reduced. I've had several XL-H1 shooters advise never to use NR1 as ghosting etc. seems to be an issue. Add to this the fact that toggling the peaking focus aid disables zebras, and you have the makings of a "Guskers" error if NR1 is on :-) NR2 sounds less problematic, and setting -3db with AGC off works well to keep noise to acceptable levels...so I'll likely use those two. Defaults for NR1 and NR2 are "off".
 
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guskersthecat said:
Well, here it is, bare cam.

It goes away with NR1 off, and exposure reduced. I've had several XL-H1 shooters advise never to use NR1 as ghosting etc. seems to be an issue. Add to this the fact that toggling the peaking focus aid disables zebras, and you have the makings of a "Guskers" error if NR1 is on :-) NR2 sounds less problematic, and setting -3db with AGC off works well to keep noise to acceptable levels...so I'll likely use those two. Defaults for NR1 and NR2 are "off".
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LMAO what happened in that clip?

But as I said its relative to NR1. Shooting without NR1, it doesnt happen. Also I wouldnt classify it as CA. Its something but not CA.

Theres an auto gain on this camera? :P Just kidding, but thats something that remains permanently off on my cam. Im shooting everything at -3db. There may come a time when 0db is useful so I always have that to play with.

Sorry just curious but why is zebras being turned off when peaking on focus is engaged a problem? Im asking this in honesty. My process is always adjust exposure, then I move on to focusing. So as a seperate function in the workflow I just dont see it as an issue.
 
It's a good question. Now that I know zebras do turn off with peaking, I can make sure peaking is off, when I set exposure :Drogar-Dum(DBG): Shooting with the adapter, and fiddling with 35mm lens focus, aperture and cam aperture etc. I tend to forget peaking is on...overexpose a few sections etc.

I've changed the title where I could to include "blue meanies" instead of CA. From what I can tell so far, the A1 lens is very good with respect to CA.
 
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