D610 long-exposure noise

Started Dec 31, 2013 | Questions thread
Luke Kaven Veteran Member • Posts: 5,705
Re: D610 long-exposure noise

fotolopithecus wrote:

Luke Kaven wrote:

fotolopithecus wrote:

Luke Kaven wrote:

chkproductions wrote:

Luke Kaven wrote:

That's the problem. LENR is all but mandatory on this camera. Suggest also letting the camera cool down after use of live view, before taking the exposure.

Would that be the same if you use an external monitor while shooting? I suppose it would be as you have to have LV engaged to use the external monitor.

Mainly the sensor itself runs hot, even for still frames, but especially when operated continuously.

Interesting, the Exmors run hot compared with what other sensors for example?

Some sensors that are less susceptible -- D3/D700, D3s, D4/Df

So fewer pixels less heat, or is that just coincidence?

The D3/D700 and D3s architecture places amplification and A-D off the sensor on a set of AD9974 chips (6 chips * 2 channels per chip).  So the sources of heat are placed away from the sensor.  In trade, very low level signals need to get moved between the sensor and the amp/A-D very fast.

In the D4/Df, amplification and A-D are done on the sensor, but limited to 24 channels, which must be multiplexed in fast readout.  Column readout circuits are mutiplexed with adjacent columns sharing a single readout circuit.  This yields some increase in DR at base ISO.  And there is enough room for deep wells that record 120k e- at ISO 100.

The D3/D700, D3s, D4/Df all require a fast readout, which favors a smaller number of pixels.

The D3x, D7000, D800, D600 use Exmor sensors, which perform column-parallel readout, with amplification and A-D on each column.  Readout is slow, but massively parallel.  But there is a lot of active circuitry requiring a lot of power, all of it on the sensor.  This architecture keeps low-level signals on the chip with slow readout for excellent levels of read noise and high DR.  But it generates a lot of heat.  It is best suited for operation at lower gain levels, mostly due to thermal noise.  Thermal noise can be mitigated though through black-frame subtraction.

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