Can a camera create multiple exposure brackets from one sensor exposure?
Asked 9/21/2011
2 views
2 answers
0
For HDR, could a camera keep aperture and ISO fixed, make one long exposure, and read the sensor partway through to save several images at different effective shutter times? For example, during a 2-second exposure, could it save a readout at 0.5 s, another at 1 s, and a final one at 2 s, producing bracketed frames from a single shutter press? Is this technically possible with normal camera sensors, or would it require a special sensor design?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
14y ago
2 Answers
4
It is kind of already done but requires a special sensor. Fuji's SuperCCD EXR and EXR CMOS sensor are wired so that they can read one half of the photosites separately from the other half. When set to EXR-DR mode (Dynamic-Range priority) half of the pixels are read partly through the exposure and the other half at the end. Fuji combines both halves with various ratios to increase the DR by up to 4 stops (1600% as Fuji labels it). The consequence is that you get image of half the resolution.
There are technical issues doing this with a normal sensor. CCD would give the most trouble since they are read by transferring the charge from one row to the next. You will notice this as a vertical line if you point a CCD camera a bright light. CMOS sensors can be read any time but causes the photosite to discharge. This is why CMOS cameras show a 'jello' effect while filming video, since it takes time to read the whole image, although things are improving, so we may get there.
Once there results would require special processing to account for motion artifacts. It gets more complicated with flash which is why Fuji turns it off in EXR-DR mode.
Originally by user1620. Source · Licensed CC BY-SA 4.0
user1620
14y ago
0
Generated from our catalog & community — verify before relying on it.
In general, not with a normal sensor in the simple way you describe. Reading a sensor usually removes or disturbs the accumulated charge, so a mid-exposure readout is effectively ending that exposure for those pixels. That makes it more like taking several electronic-shutter exposures than “sampling” one uninterrupted exposure.
There are also sensor-specific limits: CCDs are especially awkward because of how charge is shifted during readout, and CMOS sensors can be read more flexibly but bring issues such as rolling-shutter artifacts and noise/quality tradeoffs.
A partial exception has existed in special designs such as Fuji’s EXR sensors, which used different groups of photosites read at different effective exposures and then combined them for greater dynamic range, at the cost of reduced resolution.
So the idea is technically possible with specialized sensor architecture, but it is not how standard still-photo sensors normally work, and it does not fully replace conventional HDR bracketing.
Recommended products
UniqueBot
AI14y ago
Your Answer
Related Questions
Can the Canon 5D Mark III shoot an AEB bracket with one shutter press?
Can a digital camera capture multiple ISO levels in a single exposure for HDR?
Why don't cameras simulate shutter speed by combining many ultra-fast sensor reads?
What causes banding noise in CMOS sensors, and can it be reduced or calibrated out?
How does the Nikon Z9’s electronic-only shutter work, and why was a mechanical shutter no longer needed?