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Is there a way to achieve the following sequence?

  • open the shutter,
  • wait until it is fully settled in open position,
  • clear the CMOS sensor (remove accumulated charge),
  • start collecting photons,
  • finish collection of photons and process image (ADC, etc., save),
  • then close the shutter.
TFuto
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faf
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    What actual problem are you trying to solve here? – Philip Kendall Feb 10 '16 at 14:10
  • There's an IR leakage into the CMOS and I guess it's because of an IR source connected to shutter. There's a method to prevent an effect due to the vibration cause by the shutter when one tries to take pictures with narrow angle of view from objects far away. The shutter opens, then the Intergration starts and stops and the the shutter closes. I want to do the same. – faf Feb 10 '16 at 14:19
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    @TFutoPlease see related question from same OP:http://photo.stackexchange.com/questions/73554/bright-image-with-infrared-d3s-and-cap-on-image-included – Michael C Feb 10 '16 at 19:56
  • Downvoting. This might eventually be a good question, but as it is, and seeing the OP answer below which continues the "dialog", this feels like a message forum discussion. – scottbb Feb 10 '16 at 20:53
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    @TFuti When I take different pictures with same ISO and different EXPO time, the brightness stays the same. So this must be 2 flashing b by mirror movement at first and the end. – faf Feb 10 '16 at 21:04
  • The mirror moves before the shutter opens and doesn't move again until after it closes. If the brightness stays the same regardless of exposure time then the artifacts are coming from the signal processing somewhere between the pixel wells and the memory card. – Michael C Feb 24 '16 at 04:40
  • @MichaelClark The IR leakage is due to an IR LED with examines how much the shutter is open by sending the IR to the other side of the shutter so you can take pictures with precise exposure. It stays the same with different exposure times, because the IR flash only happens when the shutter goes up (and also maybe when it goes down). – faf Feb 24 '16 at 08:56

3 Answers3

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It appears you are confusing mirror lockup with the shutter being open before exposure. In Exposure Delay Mode on your Nikon D3s the mirror raises early as you have described. But the shutter does not open at the same time. It still waits and opens/shuts in the conventional manner where the sensor is energized and collecting light the entire time either curtain is even partially open.

Older cameras that use CCD type sensors can read out the entire sensor at once and would be capable of what you describe. Almost all current DSLRs, including your Nikon D3s, use CMOS sensors that are not capable of simultaneous readout. The sensor must be read and cleared sequentially. By the time the end of the sensor has been cleared, the beginning of the sensor has already been recording light again since the beginning of the clearing process. This leads to what is known as the rolling shutter effect.

Michael C
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It's Exposure Delay Mode that I could find but seems that only gives a delay at first and at the end the mirror comes down as the integration stops. I wonder if there's another option which also in the end the integration stops and then the mirror comes down.

faf
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You cannot achieve exposure time smaller than shutter open time without some hacking.

(Side note: the shutter is only fully open in Bulb mode and large exposure times, but not at fast shutter times).

(Your original question was also about exposure time smaller than mirror up time. That you can do. There is an option for Mirror Up mode in the D3S manual. This allows you to lock the mirror up, but open the shutter only after you press the shutter button. After exposure, the shutter closes and the mirror snaps back.)

TFuto
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