Why Some Cameras' no good for Imaging

[Fay]

Why is it that good quality camera's like Sony & Nikon are not used for imaging? Canon seeming to be the best

[Daniel]

I've never looked into the Sony camera's but as I understand the Nikons are un suitable because they apply some white balancing and noise reduction on the raw image, which, if your stacking actually creates noise and throws off your RGB balance.

Daniel
:O)

[Mike]

Also Canon give you the CHDK - http://chdk.wikia.com/wiki/CHDK - which gives you much greater control over the camera.

[mickw]

I know nothing technical about Sony , despite having one (Alpha 100)

Astronomical camera control software certainly seems rare for the Sony though - Long exposure etc.

I shall experiment  

[MarkS]

Also Canon give you the CHDK - http://chdk.wikia.com/wiki/CHDK - which gives you much greater control over the camera.

But can that be used for a DSLR?

Mark

[MarkS]

Fay,

I don't know much about the Sonys to be honest.  If Sony were to put the same quality chips into their cameras as the Sony chips used in the Stralight Express cameras, for example, I think the results could be stunning.

The whole Nikon range (even the most recent top of the range models) suffers from an inability to retrieve true raw frames from the camera.  The Nikon "raw" frames have already been processed internally to remove hot pixels.  This unfortunately also has the effect of removing faint stars (which the algorithm judges to be hot pixels). 

The Canons have good quality CCDs (low dark current and low read noise) and the ability to get true raw frames from the camera.  They are easily controlled to perform long exposures. 

To some extent, the Canon advantage is self perpetuating. They have very good support from astronomical software packages (both for acquisition and processing).  Baader do a range of replacement internal filters for when you decide to mod the camera for H-alpha sensitivity.  Astronomik to a range of convenient clip-in filters e.g. CLS, H-alpha etc.  It makes it more and more difficult to use an alternative camera.

Having said that, if another manufacturer brought out a camera with a very low noise and very sensitive CCD, I could see it being used quite quickly.

Mark

[Mac]

The whole Nikon range (even the most recent top of the range models) suffers from an inability to retrieve true raw frames from the camera. The Nikon "raw" frames have already been processed internally to remove hot pixels

Not quite true. The older models used to do this.
but the latest ones dont, their Raw frames are just that Raw (warts and all). The NR functions are for the Jpeg files.

Although you do have to turn off both the Noise reduction settings, as they are on by default. (high ISO & Long exposure)

Mac.

[Mike]

Also Canon give you the CHDK - http://chdk.wikia.com/wiki/CHDK - which gives you much greater control over the camera.

But can that be used for a DSLR?

Mark

Yes & No - There are some hacks around for some of the EOS range but not all.

[MarkS]

Mac,

If you are right, then that is really good news.  

Christian Buil did some tests on an early D3 model (he says with noise reduction switched off) but still noticed very obvious patterning in a dark frame caused by the noise reduction algorithm:

http://www.astrosurf.com/buil/nikon_test/test.htm

If that algorithm can be completely switched off, it makes the D3 superb for astro-work with low dark current, low read noise, and an incredibly high well depth (340,000 electrons).

Mark

[Ian]

and a big fat price tag

[Mac]

Christian Buil did some tests on an early D3 model (he says with noise reduction switched off) but still noticed very obvious patterning in a dark frame caused by the noise reduction algorithm:

Aparently that was done on a pre production issue. And they did have the issues with the Noise reduction.
The later production ones had that removed.

When i get my hands on the D3 (its wrapped untill my birthday now )
I'll do some darks and bias and post the results.

Mac