Thread: Qe vs aperture
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Old 14-10-2011, 06:10 PM
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Bassnut (Fred)
Narrowfield rules!

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Join Date: Nov 2006
Location: Sydney
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Qe vs aperture

Im looking at a 16801 chip (68% qe at 656nm ha nabg) and a 16803 (45% ha abg).

What kind of aperture difference is required at the same Fl to get the same depth image with the same exposure time?. (ignoring the increased optical res of a larger aperture)

In other words, what is the relationship between the qe of a cam and size of an OTA for the same image result.

That might seem an obscuRe way to look at things, but hi qe means read noise is a smaller proportion of signal, and many other advantages with a smaller OTA/OBS eg a 16" instead of a 20" with reducer which the Pme would struggle with.

I'm not sure about the overall cost diff, I suspect it would be the same, the 16801 ain't cheap, but I'm not so concerned about that.
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