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ASI-071MC Buffer

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#1 CCD-Freak

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Posted 16 July 2019 - 11:22 AM

I am considering upgrading to an ASI-071MC and I am wondering how much difference the buffer of the Pro version makes in the amount of amp glow?  Is it a significant amount?   Is it better with the buffer?

 

"Curious minds want to know"

 

 

John

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Edited by CCD-Freak, 16 July 2019 - 11:44 AM.


#2 Gipht

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Posted 16 July 2019 - 11:41 AM

My ASI071MC-Pro has very modest amp glow.  I have not had any problem calibrating it out.


Edited by Gipht, 16 July 2019 - 11:41 AM.

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#3 hoxca

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Posted 16 July 2019 - 01:12 PM

The buffer is good choice as it provide a better stability in the USB chain but i didn't notice any major change in the calibration image going form ASI071MC to Pro version. The sealing of the sensor chamber seems better with the pro version.

I've never got a disconnect with the ASI071MC-Pro.


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#4 CCD-Freak

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Posted 17 July 2019 - 03:27 PM

Can anyone else "shed some light" on this ?????  I need to make a decision soon.  I can get a last generation ASI-071MC-Cool for $500 less than the Pro version.  Does the buffer make that much difference in the amp glow especially when used via USB 2 ?????

 

 

John

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#5 ChrisFC

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Posted 17 July 2019 - 08:20 PM

Yes, as with others. I started with the 071-cool and got it upgraded when the pro came out - they replaced with a new camera.

Amp glow much less and stable if using USB2. Subjectively it also seems a better build.



#6 t-ara-fan

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Posted 17 July 2019 - 11:22 PM

  I can get a last generation ASI-071MC-Cool for $500 less than the Pro version.

Did they have some kind of retrofit fix for the dew issues with the Cool version? IIRC the chamber sealing was really bad, it might have been as simple as the screws holding the front on were too long to get tight.

 

I have the PRO ... no noticeable problems with glow and I mainly used it with USB2. 


Edited by t-ara-fan, 17 July 2019 - 11:22 PM.


#7 ChrisFC

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Posted 18 July 2019 - 05:30 AM

They didn't modify my 071-cool when I got it upgraded to the pro. They swapped it with a new camera. That's probably why they are selling these of??

#8 Cliff Halliwell

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Posted 18 July 2019 - 06:16 AM

Yes, as with others. I started with the 071-cool and got it upgraded when the pro came out - they replaced with a new camera.

Amp glow much less and stable if using USB2. Subjectively it also seems a better build.

Your text sort of implies it was less stable if using USB3.  True?  

 

I have a warm room away from my SkyPod and am on the verge of pulling one of my active USB2 cables out of the conduit and replacing it with an active USB3 cable (about 30 foot total run), which I have already tested somewhat (darks only, which seem quite dark!).  My new USB3 cable has a power supply at the scope end, likely to ensure adequate USB power (or I will use a powered hub).  I would still have one USB2 left, as plan B.

 

Obviously the USB3 ought to be faster, but is it less stable?  

 

I guess once I have both I will be able to test and report back!



#9 spokeshave

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Posted 18 July 2019 - 06:24 AM

Here's my limited understanding. The non-Pro version of the camera streams the readout data directly to the USB bus. This has some problems:

 

1) If there is an error in the stream, the image is lost. USB protocol does not allow for error correction and even if it did, once the readout data is sent to the bus, it is lost forever, so data could be re-sent.

2) The USB traffic has to be set such that errors in the stream are minimized.

3) The slower the USB speed, the longer the readout process takes, which increases amp glow.

 

Number 3 in particular relates to the OP's question. The amount of amp glow experienced will be directly related to the USB traffic setting. With the on-board DDR memory, the camera can read the sensor at very high speed directly to the DDR memory, which will minimize amp glow. This also has big advantages for transferring the image to the PC. Since the transfer speed is now unrelated to the readout speed, and the image is safely stored in DDR memory, it can be send to the PC over USB at any speed and the chances of a lost frame are pretty much non-existent. This is also an advantage for those who find USB2 to be more reliable than USB3. Since the amp glow is not related to USB speed, either protocol can be used without detrimental effect.

 

Tim


Edited by spokeshave, 18 July 2019 - 06:26 AM.

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#10 Cliff Halliwell

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Posted 18 July 2019 - 07:50 AM

Here's my limited understanding. The non-Pro version of the camera streams the readout data directly to the USB bus. This has some problems:

 

1) If there is an error in the stream, the image is lost. USB protocol does not allow for error correction and even if it did, once the readout data is sent to the bus, it is lost forever, so data could be re-sent.

2) The USB traffic has to be set such that errors in the stream are minimized.

3) The slower the USB speed, the longer the readout process takes, which increases amp glow.

 

Number 3 in particular relates to the OP's question. The amount of amp glow experienced will be directly related to the USB traffic setting. With the on-board DDR memory, the camera can read the sensor at very high speed directly to the DDR memory, which will minimize amp glow. This also has big advantages for transferring the image to the PC. Since the transfer speed is now unrelated to the readout speed, and the image is safely stored in DDR memory, it can be send to the PC over USB at any speed and the chances of a lost frame are pretty much non-existent. This is also an advantage for those who find USB2 to be more reliable than USB3. Since the amp glow is not related to USB speed, either protocol can be used without detrimental effect.

 

Tim

That is a nice, concise description of why a buffer is beneficial. I guess the speed of buffer readout over USB is related to frame rates, and likely a non-issue when taking longer subs (even just several seconds?) and an important issue with short subs, like planetary. 



#11 t-ara-fan

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Posted 18 July 2019 - 11:54 AM

Here's my limited understanding.

I would say your understanding is quite complete!



#12 t-ara-fan

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Posted 18 July 2019 - 11:57 AM

That is a nice, concise description of why a buffer is beneficial. I guess the speed of buffer readout over USB is related to frame rates, and likely a non-issue when taking longer subs (even just several seconds?) and an important issue with short subs, like planetary. 

With USB2 I get about 1-2fps with the full (APS) frame and full color.  So not that great for planetary, just fine for DSOs.

 

I have used the camera's full sensor for the moon, I got about 10fps with USB3.   And for planetary with a very small ROI it was >50fps.



#13 CCD-Freak

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Posted 18 July 2019 - 02:44 PM

Good info so far......

 

I will only be doing DSO imaging with subs in the 60 seconds to 300 seconds for the most part.  Right now I use USB2 but I could use USB3 with some reconfiguring of my setup.  There are some ASI-071MC-Cool cameras that have been factory refurbished with the cooling system upgraded and have the built in USB hub.  ZWO claims the only difference is the buffer.  The refurbished camera is $500 less than the Pro version and has a two year warranty.  IF there is not a huge difference in the amp glow I would be tempted to give one a try.  I have been using an ASI-1600MC-Cool V3 and USB2 with minimal issues with amp glow but the 071 camera has better specs for the well depth and dynamic range and I haven't heard of any issues with micro lens reflections.

 

My other possible route would be to get an ASI-1600MM-Pro to shoot narrow band to add to my color camera data. 

 

John Love

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Edited by CCD-Freak, 18 July 2019 - 02:45 PM.


#14 markm75c

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Posted 06 August 2019 - 02:33 PM

Good info so far......

 

I will only be doing DSO imaging with subs in the 60 seconds to 300 seconds for the most part.  Right now I use USB2 but I could use USB3 with some reconfiguring of my setup.  There are some ASI-071MC-Cool cameras that have been factory refurbished with the cooling system upgraded and have the built in USB hub.  ZWO claims the only difference is the buffer.  The refurbished camera is $500 less than the Pro version and has a two year warranty.  IF there is not a huge difference in the amp glow I would be tempted to give one a try.  I have been using an ASI-1600MC-Cool V3 and USB2 with minimal issues with amp glow but the 071 camera has better specs for the well depth and dynamic range and I haven't heard of any issues with micro lens reflections.

 

My other possible route would be to get an ASI-1600MM-Pro to shoot narrow band to add to my color camera data. 

 

John Love

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What did you end up getting.

 

I saw the HP refurb 071MC and thought maybe its a good alternative to the 1600MC (if it can even be found) or the asi294MC (will use on edge 11 with hyperstar f2 or even f7, thought maybe planetary too but maybe still use the 224 for planetary).




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