Gain Recommendation for ZWO 174mm
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Gain Recommendation for ZWO 174mm
I have tried several different gains but unsure what should be the correct range. I have gamma 50, most recently used gain 80
Suggestions?
Suggestions?
- marktownley
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Re: Gain Recommendation for ZWO 174mm
With the ZWO I wouldn't use any gain as it gets power from the USB connection, which, electrically is noisy.
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Re: Gain Recommendation for ZWO 174mm
I agree with Mark, I also use the minimum gain with all my cameras (including the ZWO ASI174MM)
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Re: Gain Recommendation for ZWO 174mm
Interesting.
Do you guys use 8 or 16 bit dynamic range? And is the gain recommendation when using Firecapture?
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Do you guys use 8 or 16 bit dynamic range? And is the gain recommendation when using Firecapture?
Oivind tangen
60N10E
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Re: Gain Recommendation for ZWO 174mm
I always use 8bit
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Re: Gain Recommendation for ZWO 174mm
Always 8 bit for me
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Re: Gain Recommendation for ZWO 174mm
I am guessing the higher frame rate, but on the down side you are losing a lot of greyscale information. I know folks insist that stacking images increases the greyscale dynamic range to 16 bit, but I can only speak from experience. With my Grasshopper the frame rate stays the same between 8 bit and 16 bit, however I capture everything at 16 bit as the dynamic range in the final image is huge compared to the 8 bit version. It makes processing a white light image a dream rather than a fight. But that is just my experience, I know nothing of the physics and others will disagree. I just know the difference
Alexandra
Alexandra
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Re: Gain Recommendation for ZWO 174mm
Will have to do a revisit and try this Alexandra, just need the sun now!Montana wrote: ↑Tue Aug 15, 2017 9:23 am I am guessing the higher frame rate, but on the down side you are losing a lot of greyscale information. I know folks insist that stacking images increases the greyscale dynamic range to 16 bit, but I can only speak from experience. With my Grasshopper the frame rate stays the same between 8 bit and 16 bit, however I capture everything at 16 bit as the dynamic range in the final image is huge compared to the 8 bit version. It makes processing a white light image a dream rather than a fight. But that is just my experience, I know nothing of the physics and others will disagree. I just know the difference
Alexandra
http://brierleyhillsolar.blogspot.co.uk/
Solar images, a collection of all the most up to date live solar data on the web, imaging & processing tutorials - please take a look!
Re: Gain Recommendation for ZWO 174mm
So yall use low gain .... what about gamma ???
My normal settings are usually 45 gain.... 1.4ms exposure .... and 1 gamma to prevent clipping
My normal settings are usually 45 gain.... 1.4ms exposure .... and 1 gamma to prevent clipping
Lunt LS100THA
TEC 140
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Lunt b1800 H-Alpha
Lunt b1200 K-Line
ZWO 174mm & 1600mm
TEC 140
AP Mach1gto
Lunt b1800 H-Alpha
Lunt b1200 K-Line
ZWO 174mm & 1600mm
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Re: Gain Recommendation for ZWO 174mm
Hi,
I agree with Alexandra that 16 bit "should" give better dynamic range but ... There was an excellent discussion about that on CN started by Emiel Kraaikamp (AS!2 & AS3) stating that the only gain would be noise in most cases. (Should try to find it back) This was mainly for planetary, and probably a little different for solar work were you have extreme dynamic range. I think one should also take into consideration the ADC present in the camera. Most webcams I know use a 12 or 10 bit ADC (ZWO for example in highspeed uses 10bit, in normal speed 12 bit on most cameras). Only exception I know at the moment is the Sony IMX 178 based cams having a 14 bit ADC (but with very small pixels not always very usefull for solar work).
So in most cases 16bit recording will probably (need some expert opinion on this) only give true 12 bit. File size will double, so the question will remain, is it worth it? I should do some testing, unfortunatelly not having much time at the moment.
For Gamma setting: i would only use NEUTRAl (linear) gamma. If not the captured signal will be crippled. Correction can and should be done in post processing.
For ZWO cam: linear gamma setting is 50 (or off in FireCapture)
Regards,
Paul
I agree with Alexandra that 16 bit "should" give better dynamic range but ... There was an excellent discussion about that on CN started by Emiel Kraaikamp (AS!2 & AS3) stating that the only gain would be noise in most cases. (Should try to find it back) This was mainly for planetary, and probably a little different for solar work were you have extreme dynamic range. I think one should also take into consideration the ADC present in the camera. Most webcams I know use a 12 or 10 bit ADC (ZWO for example in highspeed uses 10bit, in normal speed 12 bit on most cameras). Only exception I know at the moment is the Sony IMX 178 based cams having a 14 bit ADC (but with very small pixels not always very usefull for solar work).
So in most cases 16bit recording will probably (need some expert opinion on this) only give true 12 bit. File size will double, so the question will remain, is it worth it? I should do some testing, unfortunatelly not having much time at the moment.
For Gamma setting: i would only use NEUTRAl (linear) gamma. If not the captured signal will be crippled. Correction can and should be done in post processing.
For ZWO cam: linear gamma setting is 50 (or off in FireCapture)
Regards,
Paul
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Re: Gain Recommendation for ZWO 174mm
As for "crippling", this depends on the target. For prominences, I indeed use only neutral gamma. But for surface-only videos I turn the gamma down to minimum to better utilize the whole 8 bits of pixel values. This can be seen on image histogram: in my single-stacked setup, a neutral image occupies only 20-25% of histogram's width (i.e. contrast is not that great). With minimum gamma this width is greater, i.e. the raw 10/12-bit values from A/D converter are stretched before being rounded to 8 bits.
This stretching can indeed be also performed during post-processing with similar effect, but I suspect it's better to have this wider range of values before stacking (haven't verified it though!).
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Re: Gain Recommendation for ZWO 174mm
Hi Paul,
I think this is the thread you are talking about. It is very interesting!
https://www.cloudynights.com/topic/3303 ... -analysis/
Bart.
I think this is the thread you are talking about. It is very interesting!
https://www.cloudynights.com/topic/3303 ... -analysis/
Bart.
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Re: Gain Recommendation for ZWO 174mm
bart1805 wrote: ↑Mon Aug 21, 2017 8:18 pm Hi Paul,
I think this is the thread you are talking about. It is very interesting!
https://www.cloudynights.com/topic/3303 ... -analysis/
Bart.
Thanks