Do digital cameras really show more chromatic aberration than film, and why?
Asked 2/24/2014
6 views
2 answers
0
I often read that chromatic aberration appears worse on digital cameras than it did on film. Is that actually true, given that chromatic aberration is produced by the lens? If it can look worse on digital, what causes that difference—sensor pixel structure, Bayer/color filters, microlenses, angle of incoming light, or simply the higher resolving power and sampling of digital sensors?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
12y ago
2 Answers
10
Obviously, chromatic aberration is created by the lens, and the amount of CA is the same.
However, film as a medium and the sensor respond a bit differently. True perpendicular light is handled in a similar way in both, but angled light meets a different surface when using film and when using a CMOS sensor.
CMOS sensors have tiny lenses over the color filter (see here), and it is pretty hard to provide a uniform group velocity inside a small lens for all kind of light wavelengths, so these create an angle-dependent and wavelength-dependent response to arriving light. (Consider white light going through a prism - same effect).
A film has much less sensitivity to incident angle. So you will just photograph the CA.
On the other hand, R, G and B coming from an angle will see different sensor sensitivities (each is different) than RGB coming perpendicular to the sensor. So that will show up as color shift or color change, making CA worse.
Well, this is the explanation I can think of for your question.
(And a good test would be to use directed white light on a CMOS sensor, and make photos starting from perpendicular and then tilting it more and more. I would expect a bit of color shift. But do not try this at home :-) ).
Originally by user24785. Source · Licensed CC BY-SA 4.0
user24785
12y ago
0
Generated from our catalog & community — verify before relying on it.
Chromatic aberration itself is created by the lens, so the lens produces the same optical error whether you record it on film or a digital sensor. What changes is how the recording medium renders it.
Digital sensors can make CA more visible for a few reasons:
- Most sensors use a Bayer color filter array, so color is reconstructed from separate red, green, and blue samples. At high-contrast edges, this can make color fringing stand out more.
- Sensors also have microlenses and layered structures in front of the photosites. Light hitting at an angle can interact with these differently by wavelength, especially toward the frame edges.
- Sampling/pixel structure can make small color shifts more obvious. A displacement that might blend more smoothly in film grain can become visible when it falls across discrete pixels.
- Digital images are often examined at high magnification on screens, which can make CA easier to notice.
So the statement has some truth, but not because digital creates lens chromatic aberration from nothing. Rather, digital capture and processing can emphasize or reveal it more than film did.
Recommended products
UniqueBot
AI12y ago
Your Answer
Related Questions
Why do smartphone photos still show chromatic aberration with a Bayer color filter?
Were film-era lenses designed to focus RGB at different depths, and does that matter on digital?
Why were early digital camera sensors smaller than 35mm full frame?
Can a digital sensor’s reflectivity cause extra flare or ghosting with older film-era lenses?
Do modern digital cameras recover blown highlights better than older models?