SvBony SC571CC has landed

[Ardsley Astro]

Hi Robin,

Can't see anything major in the new SDK. I'm running Sensor Analysis.

I suppose what I'm getting at is which Read noise Measurement do I trust.

If the extra noise is there because images are being captured at the same time as they are being transferred to the host pc, then normal imaging won't do that and the ASCOM driver read noise would be more realistic. even when using the Native driver.

I hope that makes sense

Anthony

[Ardsley Astro]

Hi Robin,

Please ignore my last post. I think I figured it out. The answer is offset or not setting one in ASCOM driver mode. I believe read noise is substantially lower with the ASCOM driver because its getting clipped to black. If I re-run the test with the ASCOM driver with an offset I get similar figures to the native driver.

And of course you have an offset set pretty much throughout the Sensor Analysis.

I would just like to see a Sensor Analysis in HCG mode with Ultra Low Noise mode with the native driver and then I can feed that back to SvBony.

I found no issues with the new SDK but no changes that I could see either.

Regards

Anthony

[admin]

Hi Anthony,

ah, that makes sense - black level clipping would give reduced read noise figures (probably more so at higher gains where the clipping would be worse).

The SharpCap analysis will attempt to auto-set the black level to avoid clipping where it has the ability to adjust that (ie native driver). Interestingly, ASCOM now has a way to adjust the offset directly (rather than having to go via the settings window for the camea). That's relatively new (both in SharpCap and the support in ASCOM), so it's possible that the SVBony driver doesn't support that, or that it's not quite set up right in SharpCap and therefore the sensor analysis ignores it. I will check for the possibility of the latter.

cheers,

Robin

[Ardsley Astro]

Hi Robin,

It is an interesting result and does mean most of the current Touptek based cameras published Read Noise results are technically incorrect.

I still did some digging to see if I could find any results showing correct read noise in HCG mode with and without ultra mode. Closest I could find where some graphs from Player one, with the lowest gain in HCG showing 1.525 without ULRN and 1.357 with.

I haven't been able to get first light with my camera yet, So I will try and do the math for exposure time difference with the small 0.168 read noise difference.

SvBony posted on face book about there reasoning for not including ULRN and HFW, basically because of marginal benefits. I kind of agree that the benefits are minimal, but did say to them that even from a marketing perspective it should have been kept as people will avoid the SC571Cc purely because those features are missing.

It looks like a firmware update would be required to reinstate them.

Regards

Anthony

[admin]

Hi Anthony,

thanks for the update - I usually take the same approach when I am wondering if sensor data is correct - look at plots from other manufacturers like ZWO, Player One or QHY for the same model sensor (beware though that the gain values are often defined differently, but the read noises should be the same).

I tend to agree that HFW is fairly pointless in most circumstances, but the ULRN improvement is real (if small) and allows slightly shorter exposures, which might be a significant thing for some people. As you say though, not 'ticking the box' on those features is a drawback of the camera - I'm sure lots of potential buyers will be putting together a spreadsheet or similar to compare different models that they are interested in...

cheers,

Robin

[Ardsley Astro]

Hi Robin,

I did the math on exposure times for bortle 4 with my current setup. Interesting results. I'm normally in bortle 6 but do plan visits to darkers sites. The difference in exposure time is definitely not insignificant.

I've put everything I can in an email to SvBony and requested they revisit ULRN as I would like the option to be available. It's been passed to the Technical department so hopefully something will come of it.

Again thank you for your assistance with this.

Regards

Anthony