247 replies to this topic

[josh smith]

I'm starting this thread to see if there are any owners of the the QSI 683 who have had the vertical banding issue and see if they have found a fix to the issue or found a method to calibrate out the bands.  For those unfamiliar with the problem, the issue seems to be a very prevalent banding pattern that shows when frames are stretched very hard.  Normally, you would expect to be able to calibrate out the bands through the use of bias, darks, and flats.  However, for whatever reason, it seems that the banding does not always match up.  For my case I've been able to subtract the bias from the darks and get what appears to be a band free master dark, but that is the extent of the luck that I've had.  Using bias or dark frames on the lights or flats does not seem to work.  It's been suggested recently that the cause may be taking images at low temperatures in the winter (<40-50*F) causes the fan and TEC cooler to run at only 30-40% and maybe changes the banding pattern.  There seems to be some anecdotal and repeatable data that supports this, although not a full set of evidence yet.  As a bit of a background, I've previously owned a QSI 683 and did not have the problem to this extent at all.  I also own a QSI 690 and don't have the problem with that either.

 

What I hope this thread can generate is sort of a survey on whether a user has seen the banding, whether its been able to calibrate out with normal calibration and processing, or whether some other calibration method was used to produce desirable images.  So if you are a QSI 683 user, I'd appreciate if you could take a couple of minutes to answer each of these questions and definitely would love to hear of any solutions.

 

1.  Do you see banding in your stretched frames? (bias, flats, darks, lights)

2.  Do these always calibrate out correctly with proper calibration frames?  

3.  If they don't always calibrate out, do you see a temperature dependency?  

4.  Have you found a solution to calibrate differently to remove the banding issue?

5.  What have you tried if you haven't succeeded yet?

 

I should add that this has been discussed at length in the Yahoo Group here, https://groups.yahoo...18928?reverse=1 , and it has been determined by QSI that they were unable to reproduce the problem.  They have a series of tests they recommend running, but as of now, it seems like assistance from that avenue is a dead end for now.  They do suggest contacting them if you feel you can recreate the problem, so I have and am awaiting an answer.

 

All of these are obviously shown with an STF applied...  The fits files can be found here...  https://www.dropbox....IM3ZOzdx7a?dl=0

 

 

683 30min -20 master dark by Onejoshsmith, on Flickr

 

683 master bias by Onejoshsmith, on Flickr

 

lum_test with flats and bias applied by Onejoshsmith, on Flickr

Edited by josh smith, 21 April 2015 - 08:41 PM.

[josh smith]

I'll be the first to answer my questions.

 

1.  I see vertical banding in all of my frames, but they become much more apparent when data is stacked.

2.  On my old camera they almost always calibrated out correctly.  On my new 683, I haven't got them to calibrate yet.

3.  Not sure if it is temp dependent since I haven't get a successful calibration yet.

4.  I have not found a solution yet.

5.  I've tried isolating the camera.  I've tried both isolated DC and AC supplies including the stock brick.  I've tried bias only calibration, dark only calibration, flats and bias calibration, and flats and darks calibration and none of them will work with either my first set of calibration files or the second set I just retook. 

 

 

My next steps in testing would be to try to use bias frames taken at full 90% cooling.  If that doesn't work, I'd like to try bias subtracted darks only.  If that doesn't work, I'd like to try bias subtracted darks, and bias subtracted flat darks.  Further testing would include trying to take the bias and dark frames in the fridge and or freezer.

 

Other questions I have might be if you need to take a non zero timed bias frame?  Will it make a difference if the shutter is open or closed assuming you are in a completely dark environment?  

Edited by josh smith, 21 April 2015 - 08:27 PM.

[gezak22]

Have you read through this?

[josh smith]

Have you read through this?

 

Yes I have and thank you for sharing.  That is not the same type of banding issue.  I'll get the frames and images uploaded shortly.

[gezak22]

 

Have you read through this?

 

Yes I have and thank you for sharing.  That is not the same type of banding issue.  I'll get the frames and images uploaded shortly.

 

I thought you had, I just wanted to make sure.

 

While I cannot help with your survey, I do have some suggestions, some of which you may have already tried.

Could this be due to electrical crosstalk between the power cable and the USB cable? If the cables are widely separated, do you see the same issue?

Could it have anything to do with the computer you are using? My old laptop produced a diagonal banding that I do not see when I use my newer laptop - drivers and capture program were the same though. Updating the bios of my old laptop helped a bit, but the banding was still present in 33% of the frames.

Is the laptop running on the 60Hz grid or its own battery or a 12V marine battery that is connected via a DC/DC converter?

 

Btw, my bias frames are 0.09s dark frames, I take them in a dark room typically at the same temp as the lights, I do not use darks, but I do dither every frame.

[josh smith]

 

 

Have you read through this?

 

Yes I have and thank you for sharing.  That is not the same type of banding issue.  I'll get the frames and images uploaded shortly.

 

I thought you had, I just wanted to make sure.

 

While I cannot help with your survey, I do have some suggestions, some of which you may have already tried.

Could this be due to electrical crosstalk between the power cable and the USB cable? If the cables are widely separated, do you see the same issue?

Could it have anything to do with the computer you are using? My old laptop produced a diagonal banding that I do not see when I use my newer laptop - drivers and capture program were the same though. Updating the bios of my old laptop helped a bit, but the banding was still present in 33% of the frames.

Is the laptop running on the 60Hz grid or its own battery or a 12V marine battery that is connected via a DC/DC converter?

 

Btw, my bias frames are 0.09s dark frames, I take them in a dark room typically at the same temp as the lights, I do not use darks, but I do dither every frame.

 

 

Thank you Geza...  I have tried separating the cables and I believe that this kind of interference is more of a potential hearsay issue than a legitimate issue.  I've not seen actual evidence of that being an issue anywhere and understand that due to the nature of the digital signal it is more likely to be a total failure or work fine.

 

 I've tried with two computers running both on 12v supplies and their own 60Hz supplies as well as the camera connected to both a 12v supply or its own 60Hz supply.  The one computer has already been used successfully with my old 683 and is currently being used successfully with my 690.  

 

Did you select 0.09 seconds for your bias for any reason in particular.  I know the supposed quickest shutter time of the camera is 0.04 seconds, but that shouldn't matter since you can just keep the shutter closed, correct?

[anismo]

Hi Josh,

 

As you know I have been dealing with this issue as well with my QSI683. I did go down the path of checking for electrical interference. I tried with AC power, DC power supply, Battery and all of them had banding. I also checked by making sure the cables are far apart (other than the place where it connects to the camera, the data cable and power were completely in different direction. It did not affect it at all.

 

I am attaching the QSI analysis sent to me by the QSI tech support. They have done test with a customer camera that had banding and were not able to reproduce it but again their tests were in warm ambient temps. I also tried the steps they have listed in their report and was getting clear darks. 

 

 you have very prominent banding in your  master bias than mine but I think it will still be cleanly calibrated away. My lights also exhibit banding mostly on the left half of the image.  

 

If you are able to test this in controlled condition,  may be take a series of lights with a artificial star indoors and note the ambient temp as well as the TEC values and see if you are able to reproduce the banding, If so, it might be helpful to report the QSI tech team.

Attached Files

•  QSI_Analysis_of_Reported_Banding.pdf   127.95KB   231 downloads

[Footbag]

I don't want to mess up your poll, but I saw this with my STF-8300.  I know Pfile did as well on his STF.  I though it was an STF only issue.  

 

Since QSI couldn't reproduce it, I wonder if there could be something else going on.  

 

For me, the banding would show up randomly.  It would take a power down and wait 10m before it disappeared.  At that point, it could easily pop up at any moment.  Mine showed up in all temperatures.  I think that it would calibrate out if it was in every frame.  But, it's not consistent.  So it's in some and not in others.  That prevents it from stacking out.  

 

I would love to know what caused this.  I missed a few dark site outings because of this issue. 

[vpcirc]

There are tests you can do and a detailed explanation of possible causes on the QSI website

 

http://qsimaging.com...rpret_ffts.html

[jaddbd]

1.  Do you see banding in your stretched frames? (bias, flats, darks, lights)  -Y

2.  Do these always calibrate out correctly with proper calibration frames? -Y  (except once or twice with weak data)

3.  If they don't always calibrate out, do you see a temperature dependency? -N  not this kind of banding

4.  Have you found a solution to calibrate differently to remove the banding issue? for other banding Yes (see below)

5.  What have you tried if you haven't succeeded yet?

 

Josh,

 

Your darks and bias look similar to my 683.  Mine calibrate out nicely.  If you want to post a few unprocessed subs and a flat master, I can try to calibrate to see if they come clean using what I use for calibration software.  That might help rule out or in a software issue.  I have seen some slight banding shine thru on only on some washed out, throw away data with bright background and weak data a couple of times in the 2 years I have owned the camera.  FYI -I have one of the cameras that had the other banding issue as referred to in Geza's earlier post.  That banding shows up in below freezing temps when the set temp is close to the ambient and the cooler is barely running (at <30% or so).  I sent the camera back to QSI about a year and a half ago for a component upgrade which helped, but I can still reproduce the banding.  Solution for me on that issue is simply to the camera colder and turn the fan off when the conditions dictate.  i.e. - when the temp goes to around 0F, I have take the camera to -35C no fan.  I will send you an email detailing my correspondence with QSI on that issue for reference.

 

 John D 

[gezak22]

Thank you Geza...  I have tried separating the cables and I believe that this kind of interference is more of a potential hearsay issue than a legitimate issue.  I've not seen actual evidence of that being an issue anywhere and understand that due to the nature of the digital signal it is more likely to be a total failure or work fine.

 

 I've tried with two computers running both on 12v supplies and their own 60Hz supplies as well as the camera connected to both a 12v supply or its own 60Hz supply.  The one computer has already been used successfully with my old 683 and is currently being used successfully with my 690.  

 

Did you select 0.09 seconds for your bias for any reason in particular.  I know the supposed quickest shutter time of the camera is 0.04 seconds, but that shouldn't matter since you can just keep the shutter closed, correct?

 

I selected 0.09 because even if I type 0.01 sec for the exposure time, the CCD exposes for 0.09 sec.

 

I will admit that the banding you see here would require a serious EM source closely located to your setup - like a cell tower, 2 meters away (a wild guess) - IF there is nothing wrong with your setup. But a poorly isolated cable, a poor solder joint on a PCB, or a bad capacitor, can cause such banding.

 

Have you tried QSI's suggestion in Anis' link - subtract a master bias from a master dark? If you can live without this camera for a while, why not send it to QSI and have them inspect it? That certainly would tell you if it's a problem with the CCD or something external on your end.

 

Once you try to pull even fainter signals out of the noise level, you might see (a much fainter) banding due to interference. In my field if we want to be absolutely certain that we are not letting 60 Hz noise into our measurements, we will operate our photodetectors using batteries rather than expensive DC power supplies. But don't worry about this for now as you have bigger problems to solve. I'm just saying that interference is a real thing though typically it's a much weaker signal than what you have here.

 

Post shower update: Given that your 690 does not show any kind of pattern noise (banding), my best guess is that there is something wrong with the electronics (bad solder joint, bad capacitor, ...) of your 680, because QSI has a reputation for good electronics that do not introduce pattern noise (unless something breaks inside the camera).

Edited by gezak22, 22 April 2015 - 11:58 PM.

[BenKolt]

Josh:

 

Your post has come along in a most timely fashion as I am presently working through this exact same issue and trying to diagnose if I have a real camera problem or a calibration procedure problem.  I have a QSI 683wsg-8.  Here are my answers to your questions:

 

1.  Do you see banding in your stretched frames? (bias, flats, darks, lights) : Yes

2.  Do these always calibrate out correctly with proper calibration frames? : No

3.  If they don't always calibrate out, do you see a temperature dependency? : My temperature range is typically too small to discern this, but I'll look through my records and see if I have examples of the same target having been processed at different temperatures.  I'm currently collecting lots of frames at different temperatures just to see how the banding is affected, but so far applying to a small number of light frames of just a few targets.

4.  Have you found a solution to calibrate differently to remove the banding issue? : Not yet

5.  What have you tried if you haven't succeeded yet? : I just started the process to collect frames at different temperatures and conditions to try to isolate the source of the problem.

 

Later this evening I'll upload some of my images, bias frames, etc. that I've produced and demonstrate where I have banding.  If you or anybody else has any suggestions on what to try next, please let me know.  One possible outcome of all of this is to collect evidence to present to QSI to justify them changing the electronics in my camera or take some other action to address the issue.  I have a bit of homework to do first, however.

 

Best Regards,

Ben

[Uppie]

Josh:

 

I purchased a QSI683wsg in March and have the same issue as you and Ben. Answers to your questions:

 

1.  Do you see banding in your stretched frames? (bias, flats, darks, lights) : Yes
2.  Do these always calibrate out correctly with proper calibration frames? : No
3.  If they don't always calibrate out, do you see a temperature dependency? : Same at -25, -30, -35
4.  Have you found a solution to calibrate differently to remove the banding issue?:No
5.  What have you tried if you haven't succeeded yet? :Processed in both Pixinsight and Maxim DL with the same result.

 

This is very frustrating after dropping $4K on a camera you would think this type of issue wouldn't exist.

 

Scott

[DeanS]

I had a new board installed in my 683 about the first of Feb but have not had a chance to do much but a couple quick tests.  Did not notice anything at the time but that was before I knew to look for any kind of banding.  Going to TSP in a couple weeks so will get a chance to give it a work out.  Fingers crossed...............

 

Dean

[Uppie]

I heard from QSI today...see below:

 

"I wanted to acknowledge your ticket, and tell you that we are investigating the problem with three customer provided cameras. Once we determine the root cause, we will advise you on how to proceed. It may take a number of weeks before we have a resolution. Sorry for the inconvenience, we'll be in touch soon."

 

It sounds like they are working on the issue...so I will standby hoping it will be resolved soon.

 

Scott

[BenKolt]

All:

 

QSI has asked me to send back my camera for servicing.  I will ship it tomorrow.  I may be one of the three they mentioned, or perhaps there are more.  I appreciate their efforts to help us on this.

 

Looking back at my images over the past several months I did find a session in which I did not have the banding issue.  Unfortunately, I am unable to isolate the differences between that session and my more recent ones.  There was either something that I did then that did not cause the banding, or the banding did not manifest itself due to the brighter objects I was targeting, and my final images washed this out.

 

What I can say is that I had seen banding in the past soon after receiving the camera over a year ago, but I had lots of other problems going on that had my attention at the time such as guiding, focusing, etc.  I had also assumed my technique had not matured enough.  Around Christmas my images did not show banding as I described before.  I note that the ambient temperature was colder then, however my targets were brighter sources than the ones I was investigating more recently.  I really saw the banding during my last sessions from about a week ago when the ambient was warmer, and when I was looking at dimmer objects such as the Leo triplet.

 

I took several series of bias frames, making master bias frames from them, and I could clearly see the banding in the master frames that appeared to differ when I (1) ran the fan speed in "quiet" vs. "full" mode and (2) when I switched the amount of cooling.  Now, what I don't know is how much difference in the banding is expected or acceptable between the master frames.  I also suspect that a more thorough investigation would be in order involving taking light and calibration frames under different circumstances, and the weather does not allow me much time under the stars during this season.

 

I'll keep you all posted on what QSI discovers when they look at my camera.  Meanwhile I'm taking the opportunity to give my filters a thorough (and hopefully safe) cleaning.

 

Dean, I'd like to hear how your camera performs with the new board when you have the opportunity.  If you were to make some bias frames and combine them into a master bias frames, do you see banding?  Or, has the new board eliminated this?

 

Best Regards,

Ben

[BenKolt]

My lights also exhibit banding mostly on the left half of the image.  

 

 

 

anismo:

 

As a matter of comparison, my master darks are quite similar to Josh's above.  My calibrated and stacked images also show more banding on the left-side of the frame.  When I apply an automatic background removal in PI, I see banding all the way across similar to Josh's final image.  I'm a member of the club.

 

Best Regards,

Ben

[Uppie]

Like a few others my bias, dark and light banding is concentrated on the left side of the frame extending almost to the middle...the right side is clean.

 

Scott

[josh smith]

I believe myself and Jon Martin are the other two cameras that are being investigated. Hopefully we will get some good resolution here soon! I'm glad QSI had decided to look into this further.

[anismo]

 

My lights also exhibit banding mostly on the left half of the image.  

 

 

 

anismo:

 

As a matter of comparison, my master darks are quite similar to Josh's above.  My calibrated and stacked images also show more banding on the left-side of the frame.  When I apply an automatic background removal in PI, I see banding all the way across similar to Josh's final image.  I'm a member of the club.

 

Best Regards,

Ben

 

 

 

Hi Ben,

 

I hope they figure out the reason. I had few threads on this myself  In my case, it started banding (with exact same setup) when it got cold. Went back and forth with QSI tech via email and sent a bunch subs for analysis and didnt get anywhere. 

 

I should note that, it is not the set point temp of the camera that had the effect but the ambient temps. I got prominent left half banding and fainter bands on the rest of the image. Here is one: http://www.cloudynig...ames/?p=6350336  (In fact I started that thread to find some info on this and I assumed it has to be related to bias/darks.. which it didnt).

 

 

It is good that they have asked to send your camera as well as Josh's camera . Hopefully they can figure out a fix (and if it is a firmware fix then even better)

 

I should note that I have absolutely no banding now (ambient temps are around 60-70F now) and it is with the exact same setup and exact same process in PI. Here is the one I took last night: http://www.astrobin.com/full/176891/0/

[DeanS]

Hi guys,

 

When I received the 683 back 2/12/15 with the new board I must have done darks that night.  I have made bias and dark masters, they look like normal masters to me.  I compared them to ones done a year before, when camera worked properly, and they look the same.   Bias has fine vertical lines which look normal, not in a banding pattern or anything.  Darks very smooth.

 

Any tests I could to on these?

 

Dean

[anismo]

@Dean,  You would want to take some lights and flats and process it to see if you have the issue or not. The bias and darks were fine in my camera when I saw banding. Even if the bias had banding it will get calibrated out (which it does currently for me) but when the banding problem is seen, the lights have banding that is in addition to the  the bands that are subtracted out by bias  . My personal experience has been correlated to ambient temp (Which may turn out to be red herring for all I know).

[DeanS]

I can do this at TSP in a couple weeks, everything is packed away.

 

As for ambient temps, that was the cause of an issue I had with it before I sent it back.  At low ambient in 2x2 I got weird horizontal streaking.  Not the same thing as the horizontal blooming, but some kind of read out issue that only happened in 2x2.  QSI finally could duplicate the issue when he thought to stick it in a fridge to cool it down.  Once he saw my issue he determined it needed a new board.  May have been more to it than that but at least during my test upon repair it looks normal in all binning modes.

 

Dean

[BenKolt]

Dean, thanks for your insight.

 

I'm shipping my camera off today, and hopefully QSI can get to the bottom of it, particularly with several cameras to examine.  When it is returned I will make new bias and dark frames, including masters, in order to compare with my previous sets that I just did recently.

 

I am also suspicious that there may an ambient temperature component to all this which would then be related to how hard the TEC has to work to maintain a set cooling temperature or to drive to even lower temperature when the ambient is cooler.  If this is the issue, then I can envision scenarios in which lights, calibrations, darks, etc. are being taken at different times when the ambient temperature has changed, even if the set cooling point is the same for all frames, but the % of TEC cooling varies.  At this point this is all purely conjecture on my part.

 

I had wanted to do the refrigerator test for comparison, but then QSI asked me to send the camera in for servicing, and I'm happy to have them do a more professional examination.  I'll decide what tests I'll perform when the camera is returned.  Obviously, if a clear cause is identified and fixed, I'll not be interested in scrutinizing it anymore.

 

Best Regards,

Ben

[Peter in Reno]

I read QSI analysis on QSI 683 cameras and saw the following:

 

"Ambient temperatures from ‐25C to 35C, but primarily around 25C."

 

It does not seem that they did extensive testing at low ambient temperatures (below freezing). Are they aware of people reporting better performance when ambient temperature is warmer?

 

Peter