Hi folks,
I've recently switched from a Canon 7d to a 5d3, and I'm using most of the same lenses (I went with full frame compatible for all but the sIgma 10-20 in anticipation of going ff).
My question is this: Are chromatic aberrations more pronounced when using a fullframe camera? My 24-105 (which is truly a wide angle lense on this body) sems to have more CAsthan I remember, so I'm stopping down to f/8 to minimize them, even when doing action or other shots where shallow df might be better. I have been shooting a lot in snow, so that could be be part of the issue too, since I haven't done lot of that.
Is there a technical reason for CAs to be worse in ff sensors paired with wide angle than in crop sensors?
Posted by Basil Greber on January 4, 2016 at 3:48 AM
Lateral CAs increase towards the image borders, so yes, a given lens may exhibit more CAs on full frame than on an APS-C sensor. That said, while there is likely more CA, as measured in micrometers, whether the sensor will also resolve it more depends on the pixel density (i.e., if the full frame and the APS-C sensor have the same resolution, the CA on the full frame sensor likely does not look worse, because the pixel density is much lower; if the sensors have the same pixel density, then the CA likely does look worse on full frame).
I don't know about Canon cameras, but Nikon cameras remove CAs automatically when shooting JPGs, and tools like Lightroom (or likely any other RAW converter) can remove them easily when converting RAW files. So I would not worry too much about CA - it's an aberration that's relatively easily corrected in post-processing.
Thanks, Basil. I did some research on it last night too. And I do shoot raw and can remove CAs easily in LR, but I just didn't expect them to be so visible in the initial raw files.
ML
Since chromatic aberration is a function of lens, and not body, due to the different distances at which R-G-B come to focus, I would not expect there to be significant difference between full frame and APS-C. That said, the comment above regarding resolving power of the sensor is interesting and I hope some others will chime in with some additional input.
I am very surprised to hear that you're seeing significant chromatic aberration with the 24-105 lens. That is one of Canon's "L" series advanced lenses with multiple lens elements as well as coatings on same specifically to mitigate chromatic aberration. If it has been dropped or jarred to somewhat misalign some elements perhaps that could be an issue? If possible to borrow another 24-105 try it and see if same results. If not, send yours to Canon for evaluation and repair.
In addition, since chromatic aberration almost always is limited to high contrast edges, you may find some exposure experimentation worth the effort. High dynamic range is something all sensors, full frame and crop factor, have difficulty dealing with.
As a side note, since jpg's are all processed images by the camera, I feel quite confident that all brands not just Nikon remove as much as possible when creating the jpg. If not already, I'd suggest moving toward RAW.
Thanks, John. I did notice it in high contrast images (dog in snow) where I was shooting pretty wide open. I suppose I could put the lens back on my 7d amd compare (duh!). I don't think I have dropped it flr at least 3-4 years ;-).
ML
Posted by Basil Greber on January 5, 2016 at 4:01 PM
"Since chromatic aberration is a function of lens, and not body [...]"
Two things:
1) On a full frame body, you use parts of the lens' image circle that are "hidden" on an APS-C sensor (because they don't fall on the sensor). And (lateral) CAs increase towards the border. So, you see the parts of the image projected by the lens that are most impacted by aberrations using a full frame sensor, but not on an APS-C sensor.
2) A lens produces a fixed amount of CA, as measured in micrometers (or any unit of distance) at some given point of the image (for a given focal length and aperture). However, how well this is visible in the image depends on the sensor resolution. If you quadruple sensor resolution in terms of MP, you double linear resolution, and you double the number of pixels that resolve a given amount of chromatic aberration.
Thanks, Basil. I think I'm understanding better now. So, in some ways, it makes sense to use a little wider focal length than the comp demands to ensure that more of the subject is in the sweet spot of the lens. This was just not something I anticipated when moving to FF, but like I said, I've only seen it in a few shots with wide apertures. I do shoot Raw exclusively, and LR has that handy little CA/defringe tool. But, I figure there will be other distortions and hiccups as I adjust to FF, and I want to get some of them under control before I do any big photo trips later this year.
Thanks,
ML
Discussion
6 repliesI've recently switched from a Canon 7d to a 5d3, and I'm using most of the same lenses (I went with full frame compatible for all but the sIgma 10-20 in anticipation of going ff).
My question is this: Are chromatic aberrations more pronounced when using a fullframe camera? My 24-105 (which is truly a wide angle lense on this body) sems to have more CAsthan I remember, so I'm stopping down to f/8 to minimize them, even when doing action or other shots where shallow df might be better. I have been shooting a lot in snow, so that could be be part of the issue too, since I haven't done lot of that.
Is there a technical reason for CAs to be worse in ff sensors paired with wide angle than in crop sensors?
I don't know about Canon cameras, but Nikon cameras remove CAs automatically when shooting JPGs, and tools like Lightroom (or likely any other RAW converter) can remove them easily when converting RAW files. So I would not worry too much about CA - it's an aberration that's relatively easily corrected in post-processing.
ML
I am very surprised to hear that you're seeing significant chromatic aberration with the 24-105 lens. That is one of Canon's "L" series advanced lenses with multiple lens elements as well as coatings on same specifically to mitigate chromatic aberration. If it has been dropped or jarred to somewhat misalign some elements perhaps that could be an issue? If possible to borrow another 24-105 try it and see if same results. If not, send yours to Canon for evaluation and repair.
In addition, since chromatic aberration almost always is limited to high contrast edges, you may find some exposure experimentation worth the effort. High dynamic range is something all sensors, full frame and crop factor, have difficulty dealing with.
As a side note, since jpg's are all processed images by the camera, I feel quite confident that all brands not just Nikon remove as much as possible when creating the jpg. If not already, I'd suggest moving toward RAW.
ML
Two things:
1) On a full frame body, you use parts of the lens' image circle that are "hidden" on an APS-C sensor (because they don't fall on the sensor). And (lateral) CAs increase towards the border. So, you see the parts of the image projected by the lens that are most impacted by aberrations using a full frame sensor, but not on an APS-C sensor.
2) A lens produces a fixed amount of CA, as measured in micrometers (or any unit of distance) at some given point of the image (for a given focal length and aperture). However, how well this is visible in the image depends on the sensor resolution. If you quadruple sensor resolution in terms of MP, you double linear resolution, and you double the number of pixels that resolve a given amount of chromatic aberration.
Hope that helps.
Thanks,
ML