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Author Topic: 12EV of DR in a compact camera through multiexposure blending  (Read 1289 times)
Guillermo Luijk
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« on: February 22, 2009, 06:39:23 PM »
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I was reading in this DPreview's article that the new Ricoh CX1 will have a special HDR mode that will allow to capture up to 12EV of DR through 2 consecutive quick captures than will be internally blended. It's the same philosophy as Fuji's Super CCD but in this case the captures are not shifted in space but in time. The goal is to apply a natural looking tone mapping.

The RAW files produced should be much less noisy in the shadows than in conventional single-shot captures. However I wonder in which situations will this mode be available since in low light conditions the overexposed capture (which must be at least 4EV overexposed to reach 12EV of DR) can require a quite long exposure time.

The blending of RAW data of different exposures is the concept we already commented in ZERO NOISE VIRTUAL RAW, but now in-camera.

And other surprises hidden in this little camera seem never-ending:
- Up to 120fps shooting in low-res
- Zone adaptive automatic white balance to deal with scenes under different lightings
- Multi-Target Auto Focus - Shoot seven images with different focal distances

BR
« Last Edit: February 22, 2009, 06:56:56 PM by GLuijk » Logged

Ray
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« Reply #1 on: February 22, 2009, 07:27:26 PM »
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Quote from: GLuijk
The RAW files produced should be much less noisy in the shadows than in conventional single-shot captures. However I wonder in which situations will this mode be available since in low light conditions the overexposed capture (which must be at least 4EV overexposed to reach 12EV of DR) can require a quite long exposure time.

Guillermo,
Does this subject deserve two threads?  

The CX1's sensor is 7.7mm diagonally. Full frame 35mm is 44mm diagonally. For a given DoF there's a 5.7 stops difference in aperture, approximately.

That means, for example, that in order to get a shot with FF 35mm that has the same DoF as a shot with the CX1 used at F3.5 and 1/800th second at base ISO, you would need to use the FF DSLR at F22 and 1/20th second, at the same base ISO.

It's not clear what the time interval is between the 2 shots taken for HDR purposes. It should be very small since the CX1 is capable of shooting video at 120 frames/sec, so let's say it's 1/120th sec (although it's likely less). In this example, the total time for 2 shots, 4 stops apart, would 1/800th + 1/50th + 1/120th =  1/35th sec (approx).


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Guillermo Luijk
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« Reply #2 on: February 22, 2009, 07:34:30 PM »
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Quote from: Ray
It's not clear what the time interval is between the 2 shots taken for HDR purposes. It should be very small since the CX1 is capable of shooting video at 120 frames/sec, so let's say it's 1/120th sec (although it's likely less). In this example, the total time for 2 shots, 4 stops apart, would 1/800th + 1/50th + 1/120th =  1/35th sec (approx).
Yes but to reach a high DR, you need a good exposure (and with a 'good exposure' I mean a good amount of light, not a high ISO with poor light), so I don't think we should look at the 1/120 speed when trying to reach 12EV of DR.

Let's see what the first tests say. The camera has several HDR modes (weak, strong,...). Maybe they don't refer (or not only) to the tone mapping applied to generate the JPEG image, but to the degree of overexposure of the second shot, and hence to the exposure time needed for it.

PS: what do you mean by a second thread? I did a search on CX1 and didn't find any -> I rectify: I see now your thread sorry (the Search engine does not produce any result for 'CX1' though).


PLEASE don't post on this thread and follow the discusion HERE.
« Last Edit: February 22, 2009, 07:49:46 PM by GLuijk » Logged

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