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DSO test shots using an ASI224 and a Goto Alt Az mount

astrophotography ccd dso EAA imaging
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#26 Stargazer3236

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Posted 10 August 2015 - 07:29 PM

Also, ZWO is coming out with cooled versions of the 174, 224 and 178 later this year.



#27 Astrojedi

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Posted 10 August 2015 - 07:50 PM

David,

I was actually thinking of moving this discussion to the EAA forum since I am now leaning more towards EAA with this camera. Will continue the thread in the EAA section to post the comparison images.

I agree that a cooled ASI224 could be very interesting but exposures don't need to be very long. I have noticed that for the brighter DSOs the histogram starts to clip on the right edge with exposures longer than 15-20 secs at 250+ gain.

Hiten

Edited by Astrojedi, 10 August 2015 - 08:20 PM.


#28 Astrojedi

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Posted 10 August 2015 - 08:11 PM

Dave,

 

I have not had a chance to try the ASI178MC yet hence I have no first hand data to draw a conclusion from. Based on the specs the bigger sensor is a plus but comes with slightly higher read noise and potentially lower IR sensitivity. The read noise may require slightly longer exposures but you should still be fine with 5 sec subs. The lower IR sensitivity is both good and bad depending on what you are viewing. Overall I think it will perform well in an EAA application.

 

I use either 1 sec or 4 sec exposures (sometimes 5 sec for fainter DSOs).

 

I use Firecap or Sharpcap to capture FITs (RAW 16). For live viewing I would use DSS Live or AstroToaster to stack.

 

In the earlier posts I have described how I take darks. For live stacking it would make sense to take 10-15 darks first and set up the calibration in AstroToaster before you start live viewing.

 

I am not aware of the sensor specs for Neximage 5 but given the very small pixel size I would definitely do 2x2 binning or even 3x3 if the camera supports it. Also subs may need to be longer if the read noise is higher.

 

Hiten



#29 wenjha

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Posted 10 August 2015 - 09:02 PM

I think ASI224MC is the best EAA camera for its super low noise

and a cooled ASI224MC defenitly would help even for short exposure such like some seconds

because the dark current must be more than 1e/s when in summer

that is much larger than its read noise


Edited by wenjha, 10 August 2015 - 09:06 PM.


#30 DonBoy

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Posted 10 August 2015 - 09:07 PM

Dave,

I'd like to point out that in Sony's spec sheet the IMX224 has 3.75um pixels and a sensitivity of 2350mV.

Where the IMX178 has smaller pixels at 2.4um and a much lower sensitivity of 425mV. 

By these numbers the ASI178 doesn't appear to be well suited to DSO imaging.  You may also want to take a look at the ASI174 with it's larger pixels (5.86um) and higher sensitivity (825mV) than the ASI178 if the ASI224 doesn't suit.


Edited by DonBoy, 11 August 2015 - 01:22 AM.


#31 Stargazer3236

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Posted 11 August 2015 - 12:12 AM

Thanks Don. In that case I will change my purchase to the 224MC in place of the 178MC.



#32 Hilmi

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Posted 11 August 2015 - 06:01 AM

Am I correct in assuming this camera will make an extraordinary guide camera? I find that in high ambient temperatures and high light pollution, guide cameras tend to suffer in performance.



#33 Mert

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Posted 11 August 2015 - 06:34 AM

  • Hi Astrojedi,

The settings were:

Shutter=5.00s
Gain=250
SoftwareGain=10 (off)
WBlue=95
WRed=52
HighSpeed=off
Brightness=1
HardwareBin=off
AutoExposure=off
Gamma=50
USBTraffic=70

 

 

 

 



#34 andysea

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Posted 11 August 2015 - 10:07 AM

I think this has been asked before but I have not seen an answer.

Does anyone know what the well depth is on the ASI224?

Thanks!



#35 Peter in Reno

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Posted 11 August 2015 - 10:14 AM

Look at the graph halfway down, it says FW = 9.4Ke. It may vary with gain. Read Noise also varies with gain.

 

http://astronomy-ima...b-3-0/asi224mc/

 

Peter



#36 andysea

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Posted 11 August 2015 - 10:16 AM

Thanks Peter! somehow I completely missed that.

With those shallow wells I suppose some sort of HDR is a must to get more dynamic range. Has anyone experimented with that yet?


Edited by andysea, 11 August 2015 - 10:18 AM.


#37 Astrojedi

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Posted 11 August 2015 - 02:27 PM

Started a sister thread in the EAA forum to discuss EAA results: http://www.cloudynig...th-nexstar-8se/


Edited by Astrojedi, 11 August 2015 - 02:27 PM.


#38 Astrojedi

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Posted 12 August 2015 - 10:15 AM

Hilmi, the camera works very well for me as a guide camera. Even with 1 sec exposures there are always many stars to choose from.

Andysea,
Using shorter exposures and stacking them significantly increases dynamic range beyond what the camera is capable of and IMO is the best way to use this camera given the very high sensitivity.

I don't recommend very long exposure astrophotography with this camera as you would saturate the pixels very quickly especially from light polluted locations.

Even with 20 sec exposures I start getting blow outs in the brighter areas.

#39 andysea

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Posted 12 August 2015 - 10:31 AM

Thanks for the feedback! 

I was thinking that longer exposures would allow going deeper and perhaps HDR combination would still preserve star color, no?



#40 Astrojedi

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Posted 12 August 2015 - 02:50 PM

Yes, HDR can help preserve star color. I not tried it though (although by stacking so many subs you are increasing the dynamic range quite a bit)

 

Total integration time is what matters for going deeper. One could potentially do hundreds of 30-45 second subs on an EQ mount. Cooling would be very helpful in mitigating the dark current. I would also prefer a larger sensor so that I have to use minimal FR.



#41 andysea

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Posted 12 August 2015 - 02:58 PM

Theoretically a large stack should work, as long as your signal is above the read noise.



#42 Stargazer3236

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Posted 16 August 2015 - 07:29 PM

Pardon for my naivete but what is HDR?



#43 andysea

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Posted 16 August 2015 - 08:02 PM

High dynamic range. You essentially combine different exposure images in order to not blow out bright areas and still get the fainter areas.



#44 gjewison

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Posted 27 August 2015 - 05:46 PM

This is an interesting thread.  I was looking at getting the ZWO ASI120MM Monochrome 1.2 Mega Pixel camera for a guiding camera and use it for planet imaging also.

 

Would I be better off getting the ASI224MC instead?  Or would the 120MM Monochrome be more sensitive than the 224MC?



#45 vpcirc

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Posted 27 August 2015 - 06:59 PM

When will this obvious advertising campaign stop? This is against the rules and it's quite obvious when the starters and contributers are same people on the Facebook page trying to sell the camera

#46 gjewison

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Posted 27 August 2015 - 11:14 PM

When will this obvious advertising campaign stop? This is against the rules and it's quite obvious when the starters and contributers are same people on the Facebook page trying to sell the camera

 

Mike did I miss something?  I was asking a legitimate question...  If I am doing something against the rules to ask for advice on what one to get for a guider and has better performance then please let me know.   



#47 Astrojedi

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Posted 27 August 2015 - 11:32 PM

When will this obvious advertising campaign stop? This is against the rules and it's quite obvious when the starters and contributers are same people on the Facebook page trying to sell the camera

 

Mike,

 

I am only sharing my experience of using a new camera. Not sure how that is against the rules.  

 

I am not affiliated with any company nor am I on any Facebook page. Honestly this is just a hobby although one I enjoy a lot. And trying out new hardware is an integral part of this very technical and fascinating hobby.

 

Not sure how you can get so worked up. Surely you have more important things to worry about in life than a few posts in a forum.

 

Please don't spoil it for the rest of us.



#48 gjewison

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Posted 28 August 2015 - 12:41 AM

Can anyone give advice on my post at all and what one I should get vs the other?

 

"This is an interesting thread.  I was looking at getting the ZWO ASI120MM Monochrome 1.2 Mega Pixel camera for a guiding camera and use it for planet imaging also.

Would I be better off getting the ASI224MC instead?  Or would the 120MM Monochrome be more sensitive than the 224MC?"

 

I wanted to get the items ordered tomorrow for a guiding package and be able to use the ASI for imaging also or at least test it out...



#49 Mert

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Posted 28 August 2015 - 03:18 AM

Don't know, I got the 224MC and the 120MC.

My guiding is great with both of them, however the 224MC

is much more sensitive and gives you more stars to lock onto.

Can't say about the difference in sensitivity between the

120MM or the 224MC, likely Sam can give you info on that!

Clear skies!



#50 Astrojedi

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Posted 28 August 2015 - 08:18 AM

I have not done a lot of planetary imaging with the 224 also I don't have a 120 to compare with but I believe the 224 is more sensitive than the 120 with lower read noise which should in theory allow for a faster frame rate.

 

For guiding also sensitivity matters so in theory you should be no worse off with the 224 as I think it is very sensitive.

 

There are many threads in the Solar system & planetary imaging forum on the 224 which you should check out.




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