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First light with ZWO 294 MC Pro

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#1 tiny68

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Posted 17 September 2019 - 02:09 PM

I recently purchased a ZWO 294 MC Pro.  I installed my C14 with HyperStar that I use for outreach events mainly last night.  I also added my new L-Enhance filter.  Collecting data with Maxim DL.  Got a good focus.  Set up to collect 60 x 60 sec subs on NGC6888.  I wanted to see what I could obtain in a near full moon/bright skies.  Once I stacked the frames and did the color conversions - everything is off on colors.  The cresent is blue.  Dean at Starizona told me to adjust the color offset x and y until I get the colors I want.  That seems to defeat the purpose of a OSC camera to me.  I will try it tonight when I get home.  Anyone else have similar issues?  I have previously collected images using an Atik 360 EX OSC and never saw anything like this.  I am hoping I missed something simply in the setup.

 

Thanks,

 

Tim



#2 DSOs4Me

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Posted 17 September 2019 - 02:14 PM

Try it with and without the filter.


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#3 jimthompson

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Posted 17 September 2019 - 02:28 PM

Hi Tim,

 

I am guessing your problem stems from the L-eNhance filter.  I have used one with my ASI294 and other OSC cameras and it has always been a challenge to get an acceptable white balance.  The problem is that the filter passes practically zero blue signal, but lots of green and red.  Since the ASI294 has 2 green pixels for every red or blue pixel, your base image comes out looking very green tinted.  Applying auto white balancing techniques can give you weird results as the tendency is to just jack up the blue channel, but in this case there is no data on the blue channel.  My suggestion is to continue to experiment until you get something that works for you.  If I remember correctly I tend to play with the in-camera R and B colour adjustments until my histograms for each colour channel look close to being aligned, then I tweak the final white balance by eye.  You will have to be careful to choose your exposure so that none of your colour channels show over or under exposure, and adjust your levels up not down to get a good balance.  Your live histogram is your friend.  :)

 

Good luck,

 

Jim T.


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#4 jimthompson

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Posted 17 September 2019 - 02:38 PM

p.s.  If it helps, the link below is to some live stack images I captured with my ASI294 and a variety of different light pollution filters.  It gives you an idea of what to expect with regards to white balance.

 

Cheers,

 

Jim T.

 

https://flic.kr/s/aHsmGkDPiX


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#5 tiny68

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Posted 17 September 2019 - 02:51 PM

Try it with and without the filter.

That will be tonight's effort if the skies hold.   Tim



#6 rkinnett

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Posted 17 September 2019 - 03:14 PM

That seems to defeat the purpose of a OSC camera to me.

Try to let go of that notion that operating an OSC camera gets you out of needing to color balance in post-processing.  There is nothing about the sensor that guarantees it will yield color balance that is either a) photometrically accurate, or b) "natural looking" to you specifically.  If you're interested in scientific accuracy then you'll need to look into photometric color calibration.  If you're interested in a "natural looking" reproduction (as if your eyes had much higher gain and exposure time) then understand that that is purely subjective, and give yourself some artistic leeway.  Here's a pretty good explanation.

 

If you're editing in Photoshop and need some tips regarding color balancing, you might find Trevor Jones' tutorials useful on his astrobackyard channel on youtube.  In particular, try his initial levels adjustments described here.

 

Keep it up!  Clear skies.


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#7 Umasscrew39

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Posted 17 September 2019 - 03:48 PM

I've been using the L-eNhance filter on my C11" with the ZWO ASI 294MC Pro.  In fact, Dean is the one who put me on to it.  I collect my data in SharpCap to get live views but then export the FITS to PixInsight to post-process.  While I am still learning how to use PI and doing AP in general, the colors from both the live views and after PP with PI are fine but you do need to experiment with it.  Many others are using this same combination with success.  Just keep at it and it will work.  



#8 tiny68

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Posted 17 September 2019 - 05:45 PM

I've been using the L-eNhance filter on my C11" with the ZWO ASI 294MC Pro.  In fact, Dean is the one who put me on to it.  I collect my data in SharpCap to get live views but then export the FITS to PixInsight to post-process.  While I am still learning how to use PI and doing AP in general, the colors from both the live views and after PP with PI are fine but you do need to experiment with it.  Many others are using this same combination with success.  Just keep at it and it will work.  

I don't mind showing my ignorance here.... what do you mean by "live view".  Does this refer to real time stacking?  Don't think I can do this in MaximDL.   Tim



#9 tiny68

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Posted 17 September 2019 - 06:06 PM

Here is an example of what I am getting...    Tim

 

NGC 6888 W azo294MC   crop processed


#10 GoFish

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Posted 17 September 2019 - 06:30 PM

Hi Tim,

 

I am guessing your problem stems from the L-eNhance filter.  I have used one with my ASI294 and other OSC cameras and it has always been a challenge to get an acceptable white balance.  The problem is that the filter passes practically zero blue signal, but lots of green and red.  Since the ASI294 has 2 green pixels for every red or blue pixel, your base image comes out looking very green tinted.  Applying auto white balancing techniques can give you weird results as the tendency is to just jack up the blue channel, but in this case there is no data on the blue channel.  My suggestion is to continue to experiment until you get something that works for you.  If I remember correctly I tend to play with the in-camera R and B colour adjustments until my histograms for each colour channel look close to being aligned, then I tweak the final white balance by eye.  You will have to be careful to choose your exposure so that none of your colour channels show over or under exposure, and adjust your levels up not down to get a good balance.  Your live histogram is your friend.  smile.gif

 

Good luck,

 

Jim T.

In several of your images I see something familiar:  a strong gradient in the green channel from left to right. I am getting a lot of stretched, stacked images that are pale green on the left, and deep magenta on the right. A “feature” of the 294?



#11 tiny68

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Posted 17 September 2019 - 06:33 PM

This is an uncalibrated stack.  60 x 60 subs under the near full moon last night.  I have read darks should be used.

 

Tim



#12 jimthompson

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Posted 17 September 2019 - 06:39 PM

In several of your images I see something familiar:  a strong gradient in the green channel from left to right. I am getting a lot of stretched, stacked images that are pale green on the left, and deep magenta on the right. A “feature” of the 294?

Heh heh, yes a feature.  Very oddly I only get the gradient in colour with the Astronomik UHC or the Meade Narrowband filters.  Other filters don't give the gradient, and on other OSC cameras the Astronomik UHC and Meade Narrowband don't give a gradient.  Very odd.  I am not the only one to observe the behavior with the Astronomik UHC.

 

Regards,

 

Jim T.



#13 jimthompson

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Posted 17 September 2019 - 06:40 PM

Here is an example of what I am getting...    Tim

 

Gah,  That looks more like your debayering is not set right.

 

Jim T.



#14 jdupton

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Posted 17 September 2019 - 07:01 PM

Jim T,

 

   I expect you are right regarding the DeBayering being off on tiny68's image. I copied it and then swapped the Red and Blue channels. After that (with a quick background neutralization) it looks completely normal. (Nice, in fact!)

 

 

 

John


Edited by jdupton, 17 September 2019 - 07:03 PM.


#15 GoFish

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Posted 17 September 2019 - 07:26 PM

Heh heh, yes a feature.  Very oddly I only get the gradient in colour with the Astronomik UHC or the Meade Narrowband filters.  Other filters don't give the gradient, and on other OSC cameras the Astronomik UHC and Meade Narrowband don't give a gradient.  Very odd.  I am not the only one to observe the behavior with the Astronomik UHC.

 

Regards,

 

Jim T.

My gradients are associated with the Celestron UHC/LPR filter.  I wouldn’t have predicted a filter would cause this. Good to know. 



#16 tiny68

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Posted 17 September 2019 - 07:27 PM

Jim T,

 

   I expect you are right regarding the DeBayering being off on tiny68's image. I copied it and then swapped the Red and Blue channels. After that (with a quick background neutralization) it looks completely normal. (Nice, in fact!)

 

 

 

John

John,

 

can an you post your reprocessing so I know it should look like.  Second - how do I fix this?  Tim



#17 jdupton

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Posted 17 September 2019 - 07:43 PM

tiny68,

 

   Sure, I'd be happy to. Here is the full image (same size as what you uploaded) with the Red and Blue color channels swapped.

 

Image53.jpg

tiny68's Image "NGC 6888 W azo294MC crop processed" with swapped color channels.

 

   The process I used in PixInisight was as follows. (Most of these operations are available in almost all image processing programs.)

  • Read in the image
  • Extract the separate R, G,and B color channels. (In PI, I used the ChannelExtraction Process.)
  • Rename the Red Channel image to Blue.
  • Rename the Blue Channel image to Red
  • Recombine the separate color channel images into an RGB Image. (In PI, I used the ChannelCombination Process.)
  • Rebalance the color of the background. (In PI, I used the BackgroundNeutralization Process.) (It didn't need much at all.)
  • Save As a JPG file.

   It took only a couple of minutes. Actually less time to do than it took to write up what I did here. smile.gif

 

   Opps, I forgot to answer about how to fix it. I am not sure where the problem arose and don't know which image processing programs you used. I can only guess that when the subs were DeBayered (converted from RAW to RGB), the wrong Bayer Matrix Pattern was used. The ASI294MC-Pro is generally said to have an RGGB pattern but some capture programs seem to call it something different. In any case, you can play with the Bayer Matrix pattern you used and find one that gives results similar to the above (although they will often have a strong greenish tint to begin with).

 

 

John


Edited by jdupton, 17 September 2019 - 09:03 PM.

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#18 Michael Harris

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Posted 17 September 2019 - 08:22 PM

This is why I love CloudyNights: I have this same camera arriving (from Starizona, in fact) in a couple of days and tiny68 brings up an issue that could affect many imagers and convinced some to chuck the camera altogether. It’s great to be part of a community of informed, curious experimenters. I hope tiny68 is able to work this out, saving me the trouble of posting later.


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#19 Umasscrew39

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Posted 18 September 2019 - 07:01 AM

I don't mind showing my ignorance here.... what do you mean by "live view".  Does this refer to real time stacking?  Don't think I can do this in MaximDL.   Tim

Correct- live or real-time viewing is the same thing.  My point was simply that you can get very good color balance views/images with this filter.  That is all.  And now from the other posts here, you can see that.  This is an excellent NB filter.



#20 jimthompson

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Posted 18 September 2019 - 10:28 AM

My gradients are associated with the Celestron UHC/LPR filter.  I wouldn’t have predicted a filter would cause this. Good to know. 

I think what is happening is something with how the camera red and blue adjustments are getting applied in the firmware.  Depending on how these are set for your specific filter, you can either see the gradient or you can't.  I have on occasion, with the UHC filter installed, been able to adjust the white balance so the gradient was not visible, but the resulting image did not look quite correct.  A very odd problem for sure.

 

Regards,

 

Jim T.



#21 tiny68

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Posted 18 September 2019 - 04:20 PM

Steven at Starizona helped me resolve the issue.  It had to do with setting the Convert Color settings in Maxim DL.  Camera needed to be set to generic RGB and offsets to 0 for both X and Y.  He made this short video to help me out and allowed me to share.

 

https://drive.google...w?usp=sharing  

 

Tim


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