SvBony SC571CC has landed

[Ardsley Astro]

Hi Robin,

Am I right in saying If you are working in Bortles 5-7 that the Light pollution noise will drown out the read noise anyway. So the change in read noise in HCG mode from 1.4 to 0.9ish won't make much difference?

Anthony

[admin]

Hi Anthony,

that depends on the exposure length - once you get to a certain length it will. Use the SharpCap 'Smart Histogram' tool to work this out for you - it will take the sensor analysis data that you have measured and combine it with a measurement of your light pollution level taken from the camera for the exact conditions that you have. Then it will calculate the exposure lengths needed at various gain values and you can see what fits in with your preferred sub length, tracking/guiding stability, etc.

cheers,

Robin

[Ardsley Astro]

Thanks Robin,
I finally got round to reading the manual a little. There are Sensor analysis results in the manual which looked like the Ultra Low Read Noise mode.
Only difference I could find was it used the Ascom Driver.

So I retested the HGC mode this morning. Low and behold the results look like the Ultra mode. So I guess I have an option should I want to try the lower read noise.

I must admit I'm very confused how that works exactly as my understanding is that Ascom is just talking to the same "Native" SDK.

Is it common for the Sensor Analysis to give different read noise with other IMX571 Camera's between the Native SDK and Ascom?

Anthony

[admin]

Hi Anthony,

no, usually ASCOM and native would give the same results providing that the camera has been configured in the same way. Of course, the ASCOM driver does its own configuration of the camera via the SDK, so it might be doing something that SharpCap isn't.

I've seen cases before where SDK versions give the wrong result when asked 'does this camera support feature X' (ie, they say no, but really it does). Then if you over-ride that and try to use the feature anyway, it works. It could be that is happening for ultra-low-noise or high full well? SharpCap is asking if the camera supports them, and if the SDK says no then SharpCap will not show the UI to control them or try to turn them on. The ASCOM driver may be ignoring all the 'asking' bit and just enabling them - who knows...

Anyway, I managed to get the ASCOM download for the camera from the SVBony site, which contains the SDK files that I need to include in SharpCap. Maybe that will help. I do need to test that those files also work with the SV715, which is also a ToupTek made, SVBony branded camera.

cheers,

Robin

[Ardsley Astro]

Hi Robin,

That's very interesting. I appreciate your input on this. It looks like Touptek do all there sensor analysis using the Ascom driver.

I did wonder if with Ascom you have to wait for the usb transfer to complete before starting the next exposure and this was the reason for the reduced noise profile. The frame rate with the Ascom being so low. It takes 30 mins to run the analysis.

I had a look at CCDciel Sensor Analysis and, using Ascom gives similar figures as Sharpcap using Ascom.

If you want to try forcing the ULRN and HFW modes. I'd be happy to assist. lol

Anthony

[Ardsley Astro]

Hi Robin, Thanks for the updates to Sharcap to include the SDK and the combined LCG/HCG sensor analysis.

I'm still waiting for anyone with a Touptek camera to run comparable test for why there is a difference between ASCOM and Native driver for Read noise.

I did find this though.

https://www.cloudynights.com/forums/top ... full-well/

The OP in that thread ran all the Analysis in ASCOM only. He is only showing the result for gain 100. Although the read noise is similar other aspects like Dynamic range do differ between LN enabled and disabled. Which would suggest that the ASCOM driver, without LN enabled behaves differently to the Native driver.

Could this be, with the ASCOM driver, the delay between images. Max FPS in Sharpcap with the ASCOM driver is 0.25 ish.
Or a delay between downloading the last exposure and taking the next.

Regards

Anthony

[admin]

Hi Anthony,

there could be something in the way that the native mode takes the images as compared to ASCOM... In Native mode, SharpCap keeps the camera in video mode until the exposure length rises above 2s, when it switches to still mode. That gives the best combination of responsiveness and frame rate in most circumstances. ASCOM is always going to run the camera in still mode, which is a difference.

You can test this out - open the camera in native mode, then unselect the 'Live View' button on the tool bar (left hand side of the toolbar), then run the analysis. In this way you put SharpCap into still mode, which forces the camera into still mode for the whole of the analysis. Once or twice I've seen analysis in still mode get stuck waiting for an image - if this happens, press the 'framing shot' button on the toolbar to take a single image and it should continue.

I also now have a newer SDK from SVBony (59.30701) - if you are interested in trying that out before I put it in next week's SharpCap update, send me an email using the 'contact us' link at the bottom of the forum page and I will forward it on to you.

cheers,

Robin

[Ardsley Astro]

Thanks Robin, emailed you for the SDK and running the analysis again now.

Regards

Anthony

[Ardsley Astro]

Hi Robin,
Ran sensor analysis, got the same as before with the native driver. I did notice the memory figure at the bottom sometimes jump up to 2. Is it possible, even in still mode, that the fpga is reading the data from the sensor at the same time as the USB transfer of the previous image.

Regards

Anthony

Screenshot 2026-02-03 221603.png (91.72 KiB) Viewed 411 times

[admin]

Hi,

the memory figure jumping to 2 is going to be unrelated to what actually happens on the camera - that's just indicating that at some points SharpCap has two separate frames from the camera in memory at once (perhaps one new one just arrived and the previous one still being examined by the sensor analysis). Unfortunately what happens inside the camera SDK or the camera FPGA/firmware itself is largely undocumented - you can sometimes work stuff out by experimentation, helped if you get a copy of the Sony datasheet for the sensor, but that's about it. Unfortunately I've not seen the datasheet for the IMX571 - they are hard to get hold of, as they are usually only released to sensor users under NDA.

cheers,

Robin