Bad frames with horizontal lines

Hi all,

I am a new user of SGP. I am now using SGP because I switched from a DSLR to a monochrome camera.
I am imaging with ASI1600 MM + EFW and ASI290 MM + OAG for guiding. My mount is an AZ EQ6.
I recently tested my imaging set up and SGP to image M33.
Everything worked perfectly : plate solving, autofocus, communication with EFW, focuser and cameras.
However, during picture acquisition around 10% of my frames were bad due to horizontal lines just killing the picture. It seems to be a kind of informatic problem like if the file have been damaged during the transfer to my PC.
Again, 90% of my pictures were good. It’s just that I don’t like to trash pictures for unknown reasons…

Could it be a kind of conflict between my 2 cams during data downloading ?

Does anyone had similar issues ?

I read already on the forum than the USB bandwidth might be something to consider. Mine is set up at 90. Could it make the difference for 2 minutes of exposure on the main cam and 3 sec looping with the guiding cam ?

Thank you in advance for your help

David

You have a USB / camera problem that either your system needs to be checked or check with ASI… Bruce Morrell

David,
How are you connecting the two camera’s to your computer? Are you using a USB hub? Is the hub powered?
How are you powering the camera?

Daz

Hi Daz
EFW and guiding cam is connected to a USB3 Hub where other things are connected (Mount and focuser). The Hub is it then connected to a USB2 port of my PC. I tryed first to have it connected to my USB3 port but it was not working (picture downloading block).
The USB Hub is powered.
The camera is also powered by USB if I get correctly. The 12V power line connected to the cam is for the cooling. The ASI290MM is powered by USB
Again the set up is working very well 90% of time. But, 10% of my frames have this stripping pattern.
I was wondering if ponctually the dowloading get corrupted by something else working in the back (guiding) like for instance if the main picture dowloading falls in the same time than guidiing picture downloading. Would it be possible ?

that stripping is caused many things, but most likely ground loop. The source is probably a bad power supply or a piece of hardware such as your camera not having a good ground or a board beginning to fail. Ground everything and see if it goes away. Every item on my pier uses one power supply with a common ground…

Bmorrelltx, Thank you for your interesting reply. The camera is brand new, but failure could happens.
Could you explain me what you mean by grounding everything ?

My power supply chain is set up like this :

I have 2 x Gel batteries (60A each) connected in parallel to double the intensity. From the batteries, I have a multiple plugs to connect the different devices :

1 One power cable directly to my mount

2 One power cable with a dedicated transfo directly to my laptop PC

3 One cable to power the devices on the tube :

  • Focuser + focuser interface

  • USB3 Hub (receiving EQMOD cable +USB focuser + USB3 cable from ASI1600MM (carrying the ASI2900MM guiding, EFW and the ASI1600MM)

  • ASI1600 MM cooling + anti-dew heater

I was wondering if should maybe connect the USB cable from the ASI directly to the PC without to go through the Hub. The point is that it’s working 90% of the time excepted when I get this stripping patterm

Should I change something on the power supply chain ? to the USB cabling maybe ?

It is a process of elimination, until you find the source. Including your PC. It can be other sources like you turning on something that creates interference…

Regards
Bruce Morrell

www.astrofactors.com

www.springcreekacademy.com

SpringCreekObservatory

214-557-5979

I need to identify the trigger. I don’t see for the moment something which could create this …
My only idea was about if picture downloading became synchrone between Guiding (3 sec loop) and imaging cam ( every 2 mins) which might create some trouble…
This is why I was thinking about USB bandwidth (right now at 90)…
I am also in contact with the ZWO support for this issue. They don’t have clear explanation for that. The problem it’s not reproducible (all the time or after a precise action from my side) …

If it is a problem with USB bandwidth, try suspending guiding while downloading, it is an option in SGP….

Regards
Bruce Morrell

Oh ! interesting ! Excellent suggestion !
I didn’t noticed this in SGP profile !
I will try this first before to touch the bandwidth !

David,

I had a similar issue (if not the same, I don’t know exactly what your horizontal lines look like) but with an Atik 428ex camera sharing a power tank with 8in OTA dew heater. It sounds like you have a lot more power than I do, and using a different camera, but when the dew heater started to drag down my battery, random horizontal black lines (missing pixel rows) would start appearing in the bottom half of my images. In my case, the 428ex actually needs the power for the camera AND cooler to run (not powered by USB). The drag on the battery was enough to drop the current to the camera to cause issues, but not actually shut the camera off. The solution for me was to just connect the camera with its own power source. Haven’t had an issue since. So, if the USB solution above doesn’t pan out, you may want to try this if you can just to rule it out.

-Stephen

Hi Stephen,
I realize that I didn’t post any pictures with this issue. Here is a good example.
Lines can be also more spread or limited to a small portion of the picture.
My dew heater is not for the tube ( I have a Newton) it’s a thin resistance sticked close to my ASI to ovoid dewing. Sorry for the misunderstanding.
It’s clear that power supply is under my radar to find the culpit
David

And a good frame the same night, same object (M33)

I would guess, that it is not a power problem, you have a speed problem on your USB connection. I would try to connect my imaging camera DIRECTLY to the laptop and not via the USB hub. I have had a similar problem and solved it with this approach.

Hope it helps
Ralf

Hi Ralf,
Thank you for your feedback.
I will try this option asap.
I just ordered a longer USB cable for that.
I will let you know if I can eradicate the problem
David

Wow, yea, that’s not at all what mine looked like. Sorry it didn’t help. :cry:

PS, lucky duck. A single frame of M33 on my rig doesn’t come close to having that much data and a whole lot of bright LP. I’d rather have the horizontal line issue and throw them out. :laughing:

Despite the banding problem, I am quiete satisfied with my new set up (ASI1600MM pro + OAG + ASI290MM + EFW LRGB + SGP)
SGP is a great software to drive everything in same time !
For M33 : It’s 2 min exposure with the L filter