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:

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.

Sounds like it's kind of analogous to class A amplification in high hifi where the amp runs hotter than the A/B amplification used in most amps. So basically it sounds like if you want the best results at lower iso's and normal exposure times you're better off with an Exmor sensor, and if you want best results at high iso's, or longer exposures you're better of with whatever's in a Df, or D3. Is that true? Thanks

As far as Class A versus Class A/B (or Class D) circuitry, I think it's a different situation.  Putting more active electronics on the sensor itself tends to make the sensor hot.  Nothing to do with efficiency.

With LENR, the D600/800 does a wonderful job.  Even on the D3s/D4/Df, I'd recommend using LENR on long exposures.

At base ISO, the D3/D3s suffer somewhat.  The D4/Df less so.

At high ISO, the D3s, D4/Df work well with no extra considerations.  [The D3/D700 have problems with pattern noise and blooming.]  But the D600/800, /if you do your own black frame subtraction/, produce wonderful results at very high ISO.  There are occasions where I would pick A D800 in these situations.  In the better lighted parts of a dark scene, the D800 will deliver some dividend in rendered detail and color.  But it requires some extra labor to get there.

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