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Brightness in ASI2600MC the same as offset in the ASI183MC?

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#1 chuckscap

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Posted 13 August 2020 - 06:48 PM

Hi my ZWO ASI183MC Pro died a few months ago, so while waiting for ZWO to repair it I decided to buy an ASI2600MC Pro.  I'll probably sell the ASI183MC when it gets back after checking it out.  My question is using Sharpcap with the ASI183MC there was an offset parameter.   I can only find a brightness parameter in Sharpcap with the ASI2600MC    Is brightness effectively offset?

 

Thanks, sorry for the beginner question

 

Chuck



#2 Umasscrew39

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Posted 14 August 2020 - 05:22 AM

Yes- in SharpCap, the brightness setting represents offset.  I use the ASI2600 with SharpCap for captures with a gain of 100 and brightness/offset of 50.  You can test for the appropriate settings by looking at the histogram to ensure you are not clipping data on the left side of the graph.  



#3 chuckscap

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Posted 14 August 2020 - 10:33 AM

Thanks so much I generated some dark libraries with an offset of 10.   Is that too low?  That's what I used to use with my ASI183MC Pro.   Is that too low?



#4 Umasscrew39

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Posted 14 August 2020 - 11:22 AM

You're welcome.

 

I've never used the 183- only the 2600, 533, 294 and 1600.  I have used as low as 20, depending on the camera but I have read many using 10 for the 183 so I suspect that is fine.  As long as you are not clipping any data, it really doesn't matter that much what value you use.  



#5 chuckscap

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Posted 14 August 2020 - 11:29 AM

Thanks again!



#6 RazvanUnderStars

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Posted 14 August 2020 - 03:41 PM

It can be, especially for higher gains. Check the histogram of an image after the dark is applied to see if the blacks are clipped. If yes, you need a higher offset. Better play safe and use something like 50 to begin with. There was a thread about this very topic recently here on CN.

 

Thanks so much I generated some dark libraries with an offset of 10.   Is that too low?  That's what I used to use with my ASI183MC Pro.   Is that too low?



#7 chuckscap

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Posted 14 August 2020 - 09:39 PM

Thanks i will redo my dark libraries and use 50 offset   

 

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#8 Umasscrew39

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Posted 15 August 2020 - 10:22 AM

Not sure why you want to do that but obviously your choice.  If you are not clipping on the left side of the histogram like I said, then no reason to do it.  Changes in gain and filters can change the left side of the histogram but it really doesn't matter as long as you are not clipping data off.  It may affect the dynamic range a little but not really a big deal.   




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