Thread: OSC v DSLR
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Old 14-02-2010, 10:41 PM
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Tunnel Vision

AlexN is offline
Join Date: Mar 2008
Location: Brisbane, Australia
Posts: 6,708
Duncan - Its not so much 16bit colour, but 16bit depth. Its a measurement of dynamic range, indicating that the sensor is capable of discerning 65536 individual, discrete shades of grey. Whether its an OSC camera or a monochrome camera, this measurement indicates how many shades of grey the camera can capture.. The difference is that an OSC CCD splits the pixels into groupings of 4, each pixel in the grouping has a tiny little filter over it that cuts out all light except the relevant information. in the QHY8 it is R G G B, pixel 1 accepts only red light, pixels 2 and 3 accept green light, pixel 4 accepts blue light. again, the pixels are only seeing 65535 shades of grey, but the filter in front of the pixels allows the camera to capture RGB data in one shot. Hence, OSC. Software is then used to debayer the grey information to create a colour image from a sensor that only detects shades of grey..

Although its already summed up,

Cooling and inherent noise levels as a result of cooling
Dramatically improved dynamic range
Increased sensitivity to all the important spectra of light.

There is no ifs, whats or buts about it... An OSC CCD imaging camera will produce better images of the night sky than even a cooled, UV/IR modified DSLR.. Not to mention that something like the QHY8 is not much more expensive than the standard consumer level DSLR like the 50D, once you pay to have the DSLR UV/IR modified, the price difference is all but gone... Then weigh up the differences between a modded DSLR and an OSC CCD..

Without a doubt, the thing that speaks the loudest (pardon the pun..) is noise... A QHY8 or any other astro camera with the Sony ICX-453 sensor has such a low dark current that dark frames are completely unnecessary even when taking 20 to 30 minute frames.. Lets see you get noise free 30 minute subs from ANY DSLR, even the most expensive DSLR's like the Canon 1D mk III / 1D mk IV and the Nikon D3Xs / D700...
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