On Jun 8, 2022, at 6:11 PM, Francesco Meschia <francesc...@gmail.com> wrote:
Not to that extreme, but I have similar bands in my ASI294MM. They’re actually random, so they average out with integration. I reckon it’s their form of read noise.
There seems to be, though, some dependency from the amount USB throttling I set. Is it the same for you?
Francesco
On Jun 8, 2022, at 7:00 PM, Karen Bieber <kaleb...@gmail.com> wrote:
Hi Rob,
Are those your dark frames? I have a ASI2600MC-Pro. Mine is color not mono, but I always get banding in my darks. It’s never been a problem during integration.
Karen
On Jun 8, 2022, at 5:53 PM, rob pfile <rpf...@gmail.com> wrote:
i put this on cloudy nights, but maybe there are some people locally that are using the ASI2600MM and can help me out.
after passing the 30-day return window, i found that my new ZWO ASI2600MM has random horizontal banding in darks and bias frames. ZWO wasn’t much help and never gave me any feedback but eventually agreed to bring the camera in for service; i sent the camera back to agena. now agena is telling me this kind of banding is normal for this camera, which i can’t really believe.
if anyone on the list is using an ASI2600MM pro would you mind sharing some darks and/or bias frames with me so i can see if my camera behaves the same as others?
youtube really mangled the quality of this video, but this is what my bin2, gain 0, offset 20 180s darks look like:
https://youtu.be/RQTQCk_57eE
only the keyframes look good and all the interpolated frames are bad but you might be able to get an idea of what i’m talking about in that video.
thanks,
rob
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i have not messed around with the USB throttling; i just left it set to whatever default was set in NINA. which way does the correlation go with the USB throttling? i’m not even sure what that knob does, are higher values higher speeds or lower speeds? this is not something that i can test now as the camera is back at agena (who are now telling me this is totally normal and they might not send it back to ZWO for repair.)
The USB Limit setting is a general, vendor-unspecific knob for camera parameters that camera vendors commonly implement for their cameras. The exact meaning of the setting and of its values will differ from vendor to vendor, and even from model to model.
perhaps this kind of banding is a normal phenomenon but the magnitude in my camera is worse.
On Jun 8, 2022, at 9:42 PM, Francesco Meschia <francesc...@gmail.com> wrote:
On Jun 8, 2022, at 9:21 PM, rob pfile <rpf...@gmail.com> wrote:i have not messed around with the USB throttling; i just left it set to whatever default was set in NINA. which way does the correlation go with the USB throttling? i’m not even sure what that knob does, are higher values higher speeds or lower speeds? this is not something that i can test now as the camera is back at agena (who are now telling me this is totally normal and they might not send it back to ZWO for repair.)The meaning of USB throttling (or “limit” as NINA calls it) is kinda dark… here’s what one of the NINA developers wrote:The USB Limit setting is a general, vendor-unspecific knob for camera parameters that camera vendors commonly implement for their cameras. The exact meaning of the setting and of its values will differ from vendor to vendor, and even from model to model.Here’s a stack of 24x180s darks at gain zero with my camera:
<PastedGraphic-1.png>
The 294 has amp glow, which can make detecting faint patterns in the master dark more difficult. To make it more visible, I did a new auto-STF on a preview that does not include the starburst pattern:
<PastedGraphic-2.png>
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For 1600mm pro, higher usb limits of 80-90 was recommended . I use 80 with my 6200mm/2600mc pro 's. Do you see the banding in lights too ?
TK
On Jun 8, 2022, at 9:45 PM, Francesco Meschia <francesc...@gmail.com> wrote:
By the way, you wrote:perhaps this kind of banding is a normal phenomenon but the magnitude in my camera is worse.
what magnitude are we talking about? If it’s compatible with the read noise stated by the manufacturer, you’re probably fine.
Francesco
On Jun 9, 2022, at 8:56 AM, rob pfile <rpf...@gmail.com> wrote:i don’t know yet, i haven’t done the analysis. basically once i saw the random banding in the darks i ran it up the flagpole at ZWO and basically never got a response. i am surprised at how “bandy” the 30x180s master dark is though. at least one person on CN is using 1000 bias frames and 100 dark frames with this sensor. it’s possible that between the smallish dither and “low” number of dark/bias subs i’m seeing problems. someone sent me a master dark from a QHY camera with the same sensor and it has vertical banding (which kind of looks like typical CCD bias banding) but very little horizontal banding.
On Jun 9, 2022, at 9:52 AM, rob pfile <rpf...@gmail.com> wrote:the question is if this is out of spec.
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On Jun 9, 2022, at 10:42 AM, rob pfile <rpf...@gmail.com> wrote:assuming the right procedure for finding the read noise in a frame is to take sdev(frame1-frame2)/sqrt(2), then convert the floating point representation in PI to DN and then convert to electrons using the gain graph given by ZWO, i get:
gain0: 3.84e- (ZWO gives 3.25e- for gain0 read noise)
gain100: 0.97e- (ZWO gives ~1.5e- for gain100 read noise)
so it seems i’m mostly within spec. it could be the higher offset in the QHY image that is masking the banding visually.
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On Jun 10, 2022, at 9:39 AM, Francesco Meschia <francesc...@gmail.com> wrote:
Hi Rob,
Here’s the (quite perfect!) Gaussian fit on the difference of your two gain-0 subs:
sigma/sqrt(2) = 3.267 ± 0.006 ADUThis corresponds to 2.509 e-… lower than what ASI says.Here’s for gain 100:
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