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Gain Settings for ASI1600MM-Cool

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#51 BillD17

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Posted 12 December 2017 - 12:27 PM

It doesn't show up in the app store.  It must be no longer available.  Bummer.



#52 kingjamez

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Posted 12 December 2017 - 12:47 PM

I downloaded it a couple of weeks ago, after first also not being able to find it. I don't know why but the app seems to come and go.

 

-Jim



#53 John_K

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Posted 05 February 2018 - 07:20 PM

Hi guys,

 

Did I see someone create an excel spreadsheet in another thread to calculate Gain/Offset settings based on focal ratio and sky darkness for the 1600 camera?

 

Thanks,

 

John K.



#54 HxPI

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Posted 12 February 2018 - 09:02 AM

I think Sharpcap v3.1 will provide similar information, once the camera and sky have been analyzed.



#55 dts350z

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Posted 23 February 2018 - 07:18 PM

OK, so I shoot for a median of 1690, or a little more, as shown in SGP, with a gain of 200 offset 50.

 

Fine.

 

Now, how can I estimate the proper exposure time WITHOUT taking 10 min. to know if a 10min exposure is correct?

 

With a DSLR, I would take short exposures (5, 10, 30, 60 seconds) at iso 12800, and when the histogram looked good, multiply that time by 8 (iso 1600 is 3 iso stops from 12800 so 2^3) to know my exposure at my shooting iso of 1600.

 

So, what can I do similar with the ASI1600? My median values don't seem to scale linearly with Gain OR exposure. 

 

Suggestions?


Edited by dts350z, 23 February 2018 - 07:19 PM.


#56 GeneralT001

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Posted 23 February 2018 - 08:22 PM

As a rule of thumb for a gain of 76:

 

L = 30s - 45s;

R = 3m

G/B = 2m

 

This gives a DN of around 1000 ish, which works well to minimize sat stars and good SNR.



#57 View2

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Posted 04 July 2018 - 07:12 PM

From what glean here, a good setting would be gain 76, offset 15. Here my bias is 210 ADU. To get the recommended 600 ADU is that.. bias ADU + Light ADU =600 , or is it just that I want ADU 600 lights for total of 800 ADU or so? 



#58 lrlinnell

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Posted 10 September 2018 - 10:30 PM

Jon Rista:

 

I understood your post up until the "413 subs would be 71.13e-". Can you share the math that is used to compute the read noise for x subs at y gain?

 

Lloyd Linnell



#59 Jon2070

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Posted 07 October 2018 - 07:16 AM

I have found this thread very useful and managed to get the correct exposures for RGB, however last night I tried OIII for the first time and struggled to get a median ADU of 850 for Gain 139 Offset 21 and also median ADU of 1690 for Gain 200 Offset 50.

 

Here are my results;

 

300s Gain 139 Offset 21 Median ADU 592

 

430s Gain 139 Offset 21 Median ADU 688

 

300s Gain 139 Offset 30 Median ADU 720

 

300s Gain 139 Offset 40 Median ADU 960

 

300s Gain 200 Offset 50 Median ADU 1328

 

380s Gain 200 Offset 50 Median ADU 1472

 

On all of them it seems like the median ADU is too low after using the equation on the first page given by GeneralT001, that is why I tried for the longer exposures, but then I am concerned that the images will be too noisy. Or is this the way forward? Keep the Gain at say 139 and offset at 21 and just increase the exposure length until I get a median ADU of 850?



#60 Darren in Tacoma

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Posted 07 October 2018 - 10:04 AM

post-149209-0-11481800-1497613559.jpg


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#61 Jon2070

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Posted 07 October 2018 - 11:04 AM

Thank you Darren, I am in an Orange Zone, 20.2 mag, I've been using the Tak which is f5, so by this I should be using 12s exposures at a Gain of 139? Does this apply to NB?



#62 View2

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Posted 07 October 2018 - 01:08 PM

I use gain 0 on the 1600mc at f5.6. For HA usually 20 to 30 min subs.
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#63 Darren in Tacoma

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Posted 07 October 2018 - 01:11 PM

Thank you Darren, I am in an Orange Zone, 20.2 mag, I've been using the Tak which is f5, so by this I should be using 12s exposures at a Gain of 139? Does this apply to NB?

I'm no guru by any means, but to keep things simple I have settled on 139 for all my RGB and 200 for narrowband. I have tried everything from 0 gain to 300 and ran into several problems when straying too high or too low. I think this chart is a good starting point, but obviously there are so many variables that a little trial and error is in order. Well, that's how I do it anyway.


Edited by Darren in Tacoma, 07 October 2018 - 01:12 PM.

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#64 Darren in Tacoma

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Posted 07 October 2018 - 01:20 PM

Also, I have never used such short exposures as 12 sec. You would wind up with so many subs and probably waste a ton of time with filter changes and dithering between subs. Personally, I would lower the gain and increase the exposure time to something like 75 gain and 45 sec to start and see how the subs look. Depends on the target, too. 


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#65 miwitte

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Posted 09 October 2018 - 10:58 AM

I just revisited this on my 1600. I was always running gain 0, 60s for lum 180s for RGB, 300s for NB. I was pretty new and this seemed a good way to make it easier. Ive been doing strictly NB and I decided to revisit my NB exposure. After some asking around and reading a ton of post it appears there is no cast in stone median ADU if you have heavy LP which I have. So it was experimentation of seeing how much gain I could use at a reasonable exposure time so I don't have hundreds of subs. It was suggested by a lot of knowledgable folks to expose up to a point where a few of the brightest stars centers are saturated. So I played with gain and opened up image in fits liberator so I could zoom in and check the levels of the stars. At least in the image I am working with now(PacMan) at gain 139 offset 50 I have maybe a dozen stars that the very centers are at 65504. At 76 I think I had a few. My subs looks way better at 139 than 76 and even better than 0 where I was. At 139 I am heavily swamping noise so my noise will be better, I'm exposed better, but I'm saturating a few stars which according to folks is ok as long as its only a few.  

 

I will definitely monitor this saturation as I do other targets but I think I'm in a better place from a exposure and noise swamping. On a side note my median ADU is in the 4000 range way over what is recommended by the spreadsheets but my LP is in the 17.5 range and the filters are 7nm so a lot of bleed through even in NB. If I had nice 3nm filters the median would be way lower. The spreadsheets are a good starting point but there are so many variables such as LP, filter bandpass etc that I feel experimentation is a must. 


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#66 Wwilmoth69

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Posted 27 January 2019 - 12:08 PM

the more I read this the more I learn and the more confused Haha

so I just went to hdr gain
and had to increase to 10min subd in narrowband to get to 400

my question is this
am I better off with these long exposures and having less of them or should I go back to unity expose to 850 and only have 5min subs but more of them to stack

my 10 min subs look better individually but if that is gonna hurt me maybe not the best thing to go longer and less subs

#67 Wwilmoth69

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Posted 27 January 2019 - 12:31 PM

heres is my Orion after switching to hdr
lum was 30sec rgb 45
this is about 400 total frames
hopefully I'll have a test of the cone nebula region in NB in another week
https://drive.google...ew?usp=drivesdk

Edited by Wwilmoth69, 27 January 2019 - 12:31 PM.

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#68 Wwilmoth69

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Posted 27 January 2019 - 06:51 PM

Also one last thing just to make sure I'm right
my bias .median is 170ish in SGP
so if I understand right to get a true 400 at hdr I need to expose to 570 on my light frames because when I callibratebit will remove thatc170 and I'm left with 400 ?

#69 bemo47

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Posted 05 May 2019 - 11:17 AM

hi,

 

i am trying to understand what should be the right gain and exposure time in my context. I have read quite all this interesting post and here are my params.

Newton 200x800 f4

ASI1600MC Cooled

Working usually at -20°C for an external temp of about 10°C to 15°C

I don't use any filters up to now

I am located in a pretty dark sky area, let says between yellow zone to green zone ?

Last shots gioves :

- 300 sec, Gain 130, mean ADU 1263

- offset mean ADU 383

which leads to 880 ADU above the offset.

if i understand well with 300 sec i am far above what is needed, especially with 130 as gain ?

based on the aboce spreadsheet i can set gain at zero in order to minimize the number of images

and test with 1, 2 or 3 mins exposure in order to get this +350/400 ADU above the offset ?

 

Do you think that i have the right understanding ?

 

PS : in some posts i can see an offset value linked to the gain value but i don't see where i can adjust this offset value (i use TheSkyX with ASCOM drivers for my ASI1600)

 

Thanks in advance,

 

Bernard


Edited by bemo47, 05 May 2019 - 11:20 AM.


#70 Jon Rista

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Posted 07 May 2019 - 11:56 PM

Sorry if this is robotic, but HOW?

With PixInsight. The cursor is a pixel probe. You can directly measure any area of an image, as a single pixel, or the mean/median/min/max for a 3-15 pixel diameter area around the current pixel. You can include masking or not. You can measure RGB/K channels, RGB+L, RGB+Y, as well as various other color models. You can measure in various integer bit depths ranging from 8 to 32 bit per pixel, or measure within PixInsight's normalized real floating point range (0.0-1.0).

 

PixInsight also offers a range of other tools to measure or prepare images for measurement. The Statistics process allows you to get many of the same measures as the probe, only over entire images or previews. You can use previews to restrict the areas measured, you can also propagate previews to other viewports (to match exact placement), extract previews into new images, etc. There are also a variety of image analysis scripts that can be used to measure and evaluate noise, contrast, SNR, etc. Most of this stuff can be integrated into your own scripts, and many of them can be invoked from the internal command line in PixInsight as well.

 

PixInsight also has batch processing capabilities via ImageContainer and ProcessContainer, in the event that you need to prepare a series of analysis steps or preparation steps for analyzing a set of images, and apply that to the full set of images in bulk.



#71 rockstarbill

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Posted 07 May 2019 - 11:58 PM

With PixInsight. The cursor is a pixel probe. You can directly measure any area of an image, as a single pixel, or the mean/median/min/max for a 3-15 pixel diameter area around the current pixel. You can include masking or not. You can measure RGB/K channels, RGB+L, RGB+Y, as well as various other color models. You can measure in various integer bit depths ranging from 8 to 32 bit per pixel, or measure within PixInsight's normalized real floating point range (0.0-1.0).

 

PixInsight also offers a range of other tools to measure or prepare images for measurement. The Statistics process allows you to get many of the same measures as the probe, only over entire images or previews. You can use previews to restrict the areas measured, you can also propagate previews to other viewports (to match exact placement), extract previews into new images, etc. There are also a variety of image analysis scripts that can be used to measure and evaluate noise, contrast, SNR, etc. Most of this stuff can be integrated into your own scripts, and many of them can be invoked from the internal command line in PixInsight as well.

 

PixInsight also has batch processing capabilities via ImageContainer and ProcessContainer, in the event that you need to prepare a series of analysis steps or preparation steps for analyzing a set of images, and apply that to the full set of images in bulk.

That post is two years old, Jon. :) 



#72 Jon Rista

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Posted 07 May 2019 - 11:59 PM

That post is two years old, Jon. smile.gif

Someone liked a post above it, and I finally saw your question. :p


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#73 NMCN

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Posted 08 May 2019 - 11:29 AM

Someone liked a post above it, and I finally saw your question. tongue2.gif

Better late than never!




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