660 replies to this topic

[CCDer]

I'm using a Pyramid PS15KX 10 Amp 13.8-Volt supply for the 1600's cooler.

 

 

 

If you have the option, you should try to put the ASI1600 on it's own isolated root hub. 

 

Thanks for the hub info Jon. I'll check this tonight when the temp goes back down in the observatory.

 

 

Mark

[CCDer]

If a powered usb hub can address most of the connection issues, which kind of hubs are good candidates?

Any link to the product would be appreciated.

 

I only have cheapo USB2 hubs with the best one being a tiny 7 port strip hub by Rosewill with power switched to two of the ports on the end. Can't find a link to the product as it is old. I ordered a better quality 4 port Belkin USB3 hub yesterday just so that I would have better testing options moving forward.

 

Edit: Now I'm not certain the power problem is with the camera or my computer not handling it and the USB drive. Or it may be the root hub issue Jon mentioned. The "dark" frames on USB2 may be caused with the driver's settings not being maintained after I've set it to the lower 45 value setting since the 90 value reappears each time the driver properties are displayed. After last night's result, all this is still in flux as are the drivers. For now I'm hoping my USB3 configuration is more stable than the atmosphere separating me from the stars.

 

 

USB3 Cable wise I'm coming off of the 1600 with the 6 foot supplied cable and I attach a single 10 foot USB3 extension between it and the Brix computer.

 

Mark

Edited by CCDer, 14 June 2016 - 01:27 PM.

[CCDer]

I tried USB3 again this evening and it refused to save any of my subs even though I had changed nothing since the previous evening. My camera is on a USB3 root hub by itself and the other root hub had only the mouse/keyboard plugged in on a single port and the USB drive via the powered hub. Even removing the USB drive entirely had no benefit. I rolled back to the ASCOM .5 driver and tested with USB2 and it typically received 19 out of 20 good frames with the 1 bad frame (being dark). I tried the .7 and .8 ASCOM driver versions with USB2 and the darkened frames increased to 10 out of 30. But then I tried the X2 driver with TheSkyX and all subs downloaded as good and was able to run a 200 point Tpoint model without incident. The X2 driver does have one weakness which is if another CPU intensive process, other than TheSkyX, is run while images are downloading over USB, the download can time out and the camera hangs. But a simple disconnect/reconnect restores it. I can live with that problem rather than losing subs to bad downloads. So I'm moving to the X2 driver until the ASCOM driver improves a bit.

 

I tested the cooler to -40 below ambient and it was running steady at 33% power at -16 degrees Celsius. Unfortunately clouds moved in again and I'll miss the 2am moonset for some nebula action. Maybe next month.

 

Mark

[Isbeorn]

 

If a powered usb hub can address most of the connection issues, which kind of hubs are good candidates?

Any link to the product would be appreciated.

I am not sure the powered USB hub is the issue since I am working with a 15 ft USB3 $8.99 cord with rock solid performance.  Not to bash other's experience, but I think it will work even with an extended USB 3 cable very well.

With all that said, a good compatible USB powered hub will serve many devices and add to comfort, organization and piece of mind to those who think it is the issue.

 

I second that. My active 5m USB 3 cord + non-powered 4-Port USB hub where I plugged in my mount, filter-wheel, guide cam and asi 1600 camera is working without any problems.

[macnenia]

This may bring a different slant on amp glow with the ZWO ASI 1600MM/C cameras.

 

I bought a ZWO ASI 1600MC in August last year.....i.e. winter here in Australia. Initially I had no problems, but as time wore on I started seeing amp glow, which by now is quite severe and limiting what I can produce from the camera. It is now summer here in Australia and at night time the temperature can be upwards of 20C (68F). After some investigation I believe the ambient temperature is the source of the issue. To test this out I ran 40 darks with the camera in the fridge at 6C (43F)......the stacked dark had no observable amp glow and a mean ADU of 1.2. After performing the same test at room temperature 22C (72F) there is very noticeable amp glow, particularly in the top and bottom right hand corners of the image and the mean ADU was 5.1. In both cases the gain was set to 150, the exposure time to 2 minutes and the set temperature to -20C (-4F), which was being achieved according to the probe readout. Theoretically the ambient temperature should make no difference to the darks so produced.

 

Here is a DropBox Link to stretch images of the two Master Darks side by side. The left hand image is the fridge test.

 

https://www.dropbox....vs 20C.JPG?dl=0

 

So why the difference? At 6C (43F) the power consumption was only about 15%-20% and the body of the camera when I removed it from the fridge is mildly warm to touch.  At 20C (68F) the power consumption was nearly 100% and the body of the camera when I picked it up is really hot to touch. I estimate it to have been at least  50C (122F). The cooling fan was working in case you are wondering.

 

It is my belief that the design of the camera (or some vagary of my version of it) is such that at warm ambient temperatures, with the solid state refrigeration system working hard to reject the heat from the sensor, the heat so produced is not being adequately removed from the body of the camera to be extracted with the cooling air. As a result the temperature of the body of the camera rises. It rises to the point where the temperature difference is great enough to force the heat to be rejected. However this means the camera gets very hot. It is more than likely that this high temperature leads some heat to be transferred by conduction to the periphery of the sensor where it manifests itself as increased dark current noise i.e. amp glow.

 

One major problem with this amp glow is it cannot be easily removed by dark subtraction. The first reason is that the amount of amp glow depends on the ambient temperature at with your lights and darks are taken. These may not be the same. Secondly there is a time dependency. When the camera is first started up it is at ambient temperature. It heats up over time, so the amount of amp glow is changing over time, such that you cannot reliably take a set of darks and know they pertain to the lights you are taking at another time.

 

For example here is a single debayered sub from my recent imaging of Thor's Helmet. The amp glow is visible to the upper and lower right of the image as a blue-white glow.

 

https://www.dropbox.... Light.jpg?dl=0

 

Here is the same sub after calibration by dark subtraction only. 

 

https://www.dropbox.... only.jpg?dl=0 

 

These darks were taken immediately after the lights, bias and flat frames. By then, it is my belief, the camera was hotter than when the lights were produced and the amp glow worse. When I did the dark subtraction the extra blue from the extra amp glow was subtracted leaving a green/ red periphery. It looks green so how do I know there is red there. When I used the SCNR routine in PixInsight to subtract green chrominance noise to try and get rid of the glow, it turns red.

 

Perhaps where owners of this camera have seen the amp glow get fixed or suddenly get worse, it's because the ambient temperature has changed.

Edited by macnenia, 19 February 2018 - 06:44 PM.

[Jon Rista]

Are you using cameras that have no cooler?

[macnenia]

Are you using cameras that have no cooler?

Hi Jon, no my camera is the ZWO ASI 1600MC, so it has the standard peltier cooler...i.e. solid state refrigeration. My conclusion is that the camera is not really capable of pulling the temperature down by 40C as specified. It can do it physically, but the camera then gets so hot, that some of that heat is leaking back to the periphery of the sensor causing amp glow. If I limit the temperature drop to 20C, the power consumptions is only ~ 20% and the amp glow doesn't occur...... I have yet to try this out, but I suspect I am much better off with a higher level of dark current noise subtracted with darks than a lower overall dark current noise but where I am unable to properly calibrate the lights due to variable amp glow.

[Jon Rista]

The camera can cool by -40C dT as advertised. That does not mean you should try to run it at maximum capacity, however. Any camera requires a buffer to allow for temperatures to fluctuate. If your ambient is 20C, then trying to cool to -20C is a futile effort...with any camera that can cool by -40C dT. You would want to cool to no less than -15C to make sure you have some room for the camera to adjust it's power level to REGULATE the temperature. Depending on the kind of temperature change you normally experience throughout the night, if you start the night at -15C and the ambient drops, then you should be fine, and as the night cools then your power levels required to cool the camera should level off and even go down. But if it stays warm or warms up, or if temperatures are inconsistent throughout the night, then you may find you can only cool to -10C consistently, leaving a 10C buffer to allow for the temperatures to fluctuate throughout the night. 

 

Generally speaking, You want the cooler power no higher than 80% on on average. This ensures that you have some headroom for the cooler power to be adjusted to regulate the temperature at your setpoint. 

Edited by Jon Rista, 04 March 2018 - 12:47 PM.

[macnenia]

Thanks Jon.

 

Actually my tests show amp glow and increasing amp glow with time when the camera control set point was ~ 20C below ambient and operating at a power level of only ~ 10-15%. i.e. a control set point of -8C when the ambient Temperature was 12C. Of course it is much less than previous trials where the temperature difference was higher, but still noticeable.

 

Cooler power at 80% of maximum would result in massive amp glow. However I do take your point that the control system can't be operating on the edge and needs some adjustment space on the high side.

[Jon Rista]

Something does not sound right there. There shouldn't be a link between amp glow and cooler power. I can re-test this, as it's been a while, but I have not noted any large difference in amp glow across temperatures, and what I have noted, the warmer the sensor and it's electronics are, the brighter the glow is.

 

If you really have a link between glow and your cooler power, then it sounds like you have some other issue going on. You may need a firmware update, or may need to send the camera in to have it examined.

[qwer]

I have problem with ASI1600MM Pro - maximum cooling occurs up to -35°C of ambient temperature. The camera is new. What does the manufacturer say cooling -45°C of ambient temperature for? Only for advertising or this a prank?

Edited by qwer, 23 October 2019 - 08:51 AM.