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Offline clive

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Bin or no bin
« on: 13:12:56, 20 November, 2017 »
Afternoon all when doing subs is it better to bin red green blue   cheers

Online Nimbus

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Re: Bin or no bin
« Reply #1 on: 13:43:17, 20 November, 2017 »
Clive it is not necessarily better but is quicker albeit you lose resolution by creating bigger pixels.  This is off-set by using a detailed Luminance channel.  This can be applied to both broadband and narrowband imaging.

HTH Jim
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Offline clive

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Re: Bin or no bin
« Reply #2 on: 13:51:51, 20 November, 2017 »
Cheers jim

Offline chris.bailey

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Re: Bin or no bin
« Reply #3 on: 14:53:55, 20 November, 2017 »
Mmm - this is one of those where different people have very different views.

My take on it is that even RGB frames have a luminance component so when you do an LRGB combine, it is not just the L that contributes to the luminance channel. The resolution does therefore suffer a little even with an unbinned L to add to the mix.

Now if you are very oversampled, say less that 1"/pxl, then binning RGB may be advantageous as the resulting binned image will still beat the seeing. Otherwise I would say not. You also need to maintain binned calibration frames which I find a chore in any event.

Also worth noting that binning involved doing an arithmetic sum of 4 pixels and placing that result in the readout register. On some cameras the readout register has the same well capacity as a regular pixel and is not full well gated SO if you are summing 4 values of say 20,000, you end up with a sum of 80,000 in a register that can only handle 65,536. It not only then clips but can bleed charge to the adjacent registers. This can lead to little horizontal ticks adjacent to bright stars. The 8300 chip is one where this happens. Worse still not all RGB channels will spill over so you tend to end up with odd coloured ticks that really show.

The big advantage is that when that summed register is read-out, there is only a single chunk of read noise compared to 4 lots of signal so you get a free signal to noise ratio boost.

Just my 2pth

Chris
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Offline clive

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Re: Bin or no bin
« Reply #4 on: 15:02:28, 20 November, 2017 »
Thanks for that full explanation   

Offline psjshep

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Re: Bin or no bin
« Reply #5 on: 20:31:18, 23 November, 2017 »
I too, Like Jim, have used 2x binning for colour to spend more time on the Luminance for more of the detail...

In the UK, for most of us.... who have average skies.... it's always a trade-off with time available... and the photons gathered...

Phil
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