Touptek G3M662M and ATR585M settings in newer Sharpcap versions

[RadHard]

Hello, i have set-up an new mini PC and i had issues with both G3M662M and ATR585M cameras. After troubleshooting according to the USB Issues guide, it turned out it was caused by the USB hub with 2m USB extension cable. Both cameras just captured bunch of frames upon start and then they stopped. Older PC with Win10 and Sharpcap dated from 30.10.25 with latest toupcam.dll works without issues with both cams. But it appears it might be just purely HW related and the USB ports on the older one work better.

As part of the troubleshooting, i also tried different versions of Sharpcap and I have noticed the latest Sharpcap 4.1.13251.0 (and bunch of other 2025 versions i tried) does not have anymore option for the LCG, HCG and HDR mode, only has Normal and HDR, is this intended? What means normal? do
es it switch between LCG and HCG automatically?
Also the gain slider goes up to 150000, this probably not intended. In the 30.10.25 version, max is at 15000.
System is Win 11 Pro 24H2

[admin]

Hi,

did you try adjusting the 'USB Speed' setting for the cameras? That allows you to adjust how hard the SDK will try to push for maximum data transfer rates over USB, and lower values can give better stability (at the cost of lower frame rates). It's possible that different SDK versions may have slightly different behaviour behind the scenes for that settings, so that a USB Speed of '1' on an older SDK might not be the same as a USB Speed of '1' on the newest SDK.

For the LCG/HCG mode, I try to avoid showing that in SharpCap and instead build in an automatic switchover at the appropriate point in the gain slider where possible. Some brands of camera (ZWO, Player One, etc) do this by default in their SDK and SharpCap doesn't need to worry. Other brands make the option to choose LCG/HCG available to software like SharpCap, and I have to set things up to recognize the sensor model in the camera and apply the right changeover point. In the case of the IMX585 camera for instance, the switch from LCG to HCG gives a gain boost of about a 9.1x increase in brightness, but HCG should not be turned on until the camera has an underlying gain of at least 1.5x to avoid issues with the image not becoming fully saturated. This means that the changeover gain for the IMX585 is gain 1365 (1365 and above is HCG). The extra gain given by the LCG/HCG switch allows SharpCap to offer an extended gain range (hence the maximum gain being higher).

When new models of camera are released (or if the manufacturer decides to rename the existing models) SharpCap cannot recognize the sensor model on the camera and therefore will show the LCG/HCG options as a fallback instead of 'Default' (which, as you guessed, is auto changeover).

thanks,

Robin

[RadHard]

Hello Robin, thank you very much for the reply.

Regarding the USB problem, the camera was basically stuck after providing maybe 20 frames and no setting changes appeared to do anything. It was not even possible to open it in different SW like NINA. I needed to reconnect the USB cable, then it worked again, but only for a while gain. Another PC did not have this problem.

How is then the gain correlating with values provided by Touptek. For example is gain 100 then the same as gain 100 provided by the charts in the camera manual? I have been suggested by various places to use the the gain 100 and HCG mode as the most optimal setting (giving large dynamic range and modest read noise), but I have myself doubts about it and need to experiment a bit around.

The gain value of 1365 you mentioned then refers to slider value as shown in Sharpcap?

Thanks

[turfpit]

Is the USB hub powered?

Dave

[RadHard]

Hello Dave, no the hub is not powered, its an 4 port Anker USB3.0 hub. Interesting is that when i connect the hub directly at the mini PC port an then go with two separate 1.5m cables to the G3M662M and ATR585M cameras, everything is fine. First i wanted to have the hub on the telescope and then connect everything from there with short cables, but the 2m extension cable was then maybe too much. All is good now, the rig is just now imaging outside.

What is interesting is how the USB3.0 destroys the the 2,4G WiFi, basically lost the remote connection instantly when i opened the camera, when the rig was already outside and maybe 20m from the router. Luckily the 5GHz WiFi runs just fine.

Now imaging the M101 with SW 62ED, i used Normal mode, gain 1400, offset 400 and 2min exposures, 6.5nm Ha filter, Moon is quite strong already. The signal looks pretty good after 40min integration.

[turfpit]

Radhard

the hub is not powered

Personally, I would always use a powered hub with devices which are doing real work (based on 20+ years commercial computing experiences since USB1 days). I have a powered USB2 hub attached to the mount and use it to connect mount, camera (cooled & mains connected), filter wheel and guider to the capture PC via a single 2m cable. This configuration has never had any problems. If reliant on the power provided by the USB port, it is possible for the connected devices to demand more power than the PC port can provide.

Interesting is that when i connect the hub directly at the mini PC port an then go with two separate 1.5m cables to the G3M662M and ATR585M cameras, everything is fine

With a USB3 camera, I always go for a direct connection (single cable) between camera and capture laptop. Again, this configuration has never shown any problems. If the USB3 camera was cooled, then I would use a mains power supply to the camera.

The software UsbTreeView https://www.uwe-sieber.de/usbtreeview_e.html can help in making informed decisions with regard to USB power usage. The diagram shows a 183M USB3 camera and how the device requires 800mA to run.

USBtreeview.JPG (178.91 KiB) Viewed 2654 times

Using the UsbTreeView software can help diagnose problems by analysing the power requirements of connected devices and comparing against the specifications of the hub being used.

Dave

[admin]

Hi,

going back to the gain values, SharpCap will stay in LCG mode from gain 100 to gain 1364 on the SharpCap slider (those values correspond with the values you will see for gain in other applications). At gain 1365 on the SharpCap slider, the camera will be switched into HCG mode and the raw gain set to 150.

Other brands with 585 cameras and auto LCG/HCG changeover do not let you access the HCG mode, raw gain=100 settings - ZWO changes into HCG at the equivalent of gain 1820, Player one at about the equivalent of gain 1120 (both of these have gains measured in 0.1dB, so you have to take 100 * 10 ^ (ZWO Gain/200) to calculte the equivalent ToupTek/Altair gain).

The usual reasoning for the limitation of not accessing the minimum gain, HCG settings is that the sensor fails to saturate when configured in this way, even with massive overexposure levels. This happens for the IMX294/IMX492 based cameras and is documented in the Sony datasheets for those sensors. The biggest problem is that if you do access these 'unsupported' settings and the sensor fails to saturate, you can end up capturing flats at what looks like a reasonable histogram, but is actually overexposed - the flats then just do not work.

cheers,

Robin

[RadHard]

With a USB3 camera, I always go for a direct connection (single cable) between camera and capture laptop. Again, this configuration has never shown any problems. If the USB3 camera was cooled, then I would use a mains power supply to the camera.

The software UsbTreeView https://www.uwe-sieber.de/usbtreeview_e.html can help in making informed decisions with regard to USB power usage. The diagram shows a 183M USB3 camera and how the device requires 800mA to run.

Using the UsbTreeView software can help diagnose problems by analysing the power requirements of connected devices and comparing against the specifications of the hub being used.

Dave

Thank you Dave! That is definitely useful, the cooled camera has separate 12V supply, the filter wheel is connected to the USB2.0 hub on the camera so that maybe takes power from it as well, i will check that, some days ago i had problem actually the filter wheel just making noise and unable to spin when it was at first also powered from the hub.
This was this first iteration of the setup over the weekend still with the old astro PC and USB hub sitting on top

Other brands with 585 cameras and auto LCG/HCG changeover do not let you access the HCG mode, raw gain=100 settings - ZWO changes into HCG at the equivalent of gain 1820, Player one at about the equivalent of gain 1120 (both of these have gains measured in 0.1dB, so you have to take 100 * 10 ^ (ZWO Gain/200) to calculte the equivalent ToupTek/Altair gain).

Awesome info Robin, thank you very much!

So if i got it right, to roughly back-calculate to the gain scale as provided in Touptek charts in HCG mode (100-15000 units), i should take (Sharpcap_gain-1365)/10 + 150. So the gain of 1000 as provided by Touptek will be somewhere around 9900? (9900-1365)/10+150 = 1003.5

[admin]

Hi,

if you are in SharpCap and have set a gain above 1365, then the correct back calculation is

ToupTek gain = SharpCap Gain / 9.10

So, if you wanted to use HCG with a touptek gain of 1000, set the SharpCap gain to 9100.

If you are below 1365 so that the camera is in LCG mode then ToupTek Gain = SharpCap Gain

cheers,

Robin

[admin]

One last thing - I should note that those calculations are valid for the 585 where the boost ratio for HCG compared to LCG is 9.1...

For the IMX662, the data I have gives a boost ratio also of 9.1, but the changeover point is 1820, not 1365.

cheers,

Robin