Something odd happening 071

[alan potts]

Right I don't know how to up load these to show you the issue. as they are FITS files from the camera.

I was very careful last night to get good focus and the first image was clean and appeared in focus with many star and a tad of colour showing on the 4 minute sub at minus 5 degrees.

It scored 9051 in DSS and other info was:- FWHM 5.79, Sky B 8.97 and 1600 stars detected, it was not even properly dark.

 

20 minutes later and dark now. 1553 scored,  FWHM 6.09,  Sky B 0.36 and 299 stars detected. Here the picture on screen was very dark and with very few stars visible and Sky B 0.36, is this possible, it was only 24 minutes after almost 9 was registed. then over the next 20 captures much the same slight better and slighty worse. Not once going back to the opening values even though I checked focus 5 times and thought it was good.

Something is going wrong here and I can't see what, when I stretch images in APT to see what I am getting, does this stretch stay as part of the file? I don't believe it does, only every other 2-3 I do a stretch. The best way I can describe the two capture is one looks like 30 seconds and the other looks like 10 minutes. Chalk and cheese.

Anyone got any ideas because when cooling is on this camera is rubbish, and I believe it is me not the camera. I did tick this Dew box in APT settings as well thinking this was the problem

Again here 6 x 4 minutes subs, no Darks Flats, cooling, anything what so ever and not good guiding either.

 

Camera with all calibration frames, best images picked, cooled at minus 5 and though maybe slightly out of focus, a terrible image. keep in mine the shot above was focused the same way by me, the size of the stars is worse than my Canon Camera.

 

 

Anyone got any ideas where I am going wrong?

alan

[Adam J]

17 minutes ago, alan potts said:

How old is your camera? You have amp glow on the bottom and that was only a feature of the very early ASI071, ask ZWO and they should fix with a firware update. 

As for the star size of the stars it is focus. I can see little black spots in the centre of the stars and thats the classic sign of poor focus. I would say you ware some way out. Its possible it slipped after you focused. 

Adam 

Edited September 23, 2019 by Adam J

[alan potts]

13 minutes ago, Adam J said:

How old is your camera? You have amp glow on the bottom and that was only a feature of the very early ASI071, ask ZWO and they should fix with a firware update. 

As for the star size of the stars it is focus. I can see little black spots in the centre of the stars and thats the classic sign of poor focus. I would say you ware some way out. Its possible it slipped after you focused. 

Adam 

Lest than one month old this is the first time I have used it really as I didn't have an IR/UV filter, here is a few frames that appeared focused but look to have a haze across the centre.

Alan

 

[Adam J]

1 minute ago, alan potts said:

Lest than one month old this is the first time I have used it really as I didn't have an IR/UV filter, here is a few frames that appeared focused but look to have a haze across the centre.

Alan

 

Sorry Alan, but when I view that full sized I still see out of focus stars I am 100% sure on this. 

Can you take a stack of dark frames with the camera and post them, you should not get the glow on the bottom of the sensor in the second image you posted (not the one in my quote). 

Adam 

[alan potts]

1 minute ago, Adam J said:

Sorry Alan, but when I view that full sized I still see out of focus stars I am 100% sure on this. 

Can you take a stack of dark frames with the camera and post them, you should not get the glow on the bottom of the sensor in the second image you posted (not the one in my quote). 

Adam 

Adam,

That is with Darks 25 of them taken at minus 5 the same as the lights. The image of M13 had no anything, and was not cooled, focused the same way, this is what I don't understand, guiding on these 40 frames last night was excellent. How do you explain the 25 frames with very little on them showing less than 200 stars in DSS.

Alan

[Adam J]

42 minutes ago, alan potts said:

Adam,

That is with Darks 25 of them taken at minus 5 the same as the lights. The image of M13 had no anything, and was not cooled, focused the same way, this is what I don't understand, guiding on these 40 frames last night was excellent. How do you explain the 25 frames with very little on them showing less than 200 stars in DSS.

Alan

The red at the bottom of the frame is in the location of the amp glow on the old non pro ASI071mc however once the went to pro and added the memory it was supposed to stop it that chip. However even if its a firmware issue then the darks should have removed it, so other explanations might include a light leak. 

Poor focus would show up as a lack of stars in DSS as the SNR of the stars would drop. 

The only other potential issue is condensation on the camera...but that would show up as a halo on the brightest star too and I just don't see that. 

Adam 

 

 

Edited September 23, 2019 by Adam J

[alan potts]

14 minutes ago, Adam J said:

The red at the bottom of the frame is in the location of the amp glow on the old non pro ASI071mc however once the went to pro and added the memory it was supposed to stop it that chip. However even if its a firmware issue then the darks should have removed it, so other explanations might include a light leak. 

Poor focus would show up as a lack of stars in DSS as the SNR of the stars would drop. 

The only other potential issue is condensation on the camera...but that would show up as a halo on the brightest star too and I just don't see that. 

Adam 

 

 

Not doubting you at all Adam but it was the same me that focused the M13 and the 1st frame of both nights is sharp at least I feel it is, focused the exact same way. Last night I checked focus 6 times in 30 frames and can't believe I am making the same mistake this amount of times. I also checked 4 times the night before. The last time I re-focused was the worst image of the night it didn't even register a number in DSS, this looked spot on using Focus Aid in APT as they all did. The same focus aid used on M13 which to me looks pretty sharp. I am going to try it next out without cooling, the Pelican shot I did I only cooled to zero and focused that once at the start, may not be perfect but here it is. 

Alan

[Adam J]

5 minutes ago, alan potts said:

Not doubting you at all Adam but it was the same me that focused the M13 and the 1st frame of both nights is sharp at least I feel it is, focused the exact same way. Last night I checked focus 6 times in 30 frames and can't believe I am making the same mistake this amount of times. I also checked 4 times the night before. The last time I re-focused was the worst image of the night it didn't even register a number in DSS, this looked spot on using Focus Aid in APT as they all did. The same focus aid used on M13 which to me looks pretty sharp. I am going to try it next out without cooling, the Pelican shot I did I only cooled to zero and focused that once at the start, may not be perfect but here it is. 

Stars look similar here I agree.

How are you focusing?  A mask or FWHM? Manual or Autofocuser? 

There is nothing about the IMX071 chip itself that could possibly result in this issue. 

Optically maybe maybe very incorrect spacing on the flattner. But again I would expect other issues. 

Adam

[alan potts]

I am focusing using focus aid in APT, I have always used this with the Canon. It is more difficult noe as I do not have USB 3 and so do not have great live view.

I have a mask coming but not here yet.

The spacing it exact I would say, the same as on the M13 shot, do you agree this looks fairly decent?

Alanh

[stash_old]

There might be another idea (long shot 🙂 ) but only if the problems occurs AFTER DSS processing.

I dont not use DSS directly but it is called as part of Astrotoaster - now and again I get weird output (from Astrotoaster via DSS) - now in Astrotoaster I can clear DSS "temp" files (via a button) and rebuild Dark Master and re-stack the images. This normally cures my problem. Sorry I haven't used DSS directly for a good while so cant remember if you can delete DSS temp files via a "button" but suspect not.

Also I am still using the "old" version of DSS (3.4 or something) not 4.

 

files are here The temporary files can require up to 100GB of space or more depending on the number of images in the set. This destination is selected under Settings > Stacking Settings > Temporary Files Folder.

 

Edited September 23, 2019 by stash_old

[symmetal]

Hi Alan,

Sorry to hear you're still unhappy with your 071. I'm not sure what the APT dew setting does but it's worth ticking the Anti dew box in the 071 Ascom Driver to ensure it's on.

This does warm the warm the window in front the sensor and works whether cooling is on or off.

I agree with Adam in that your image problems are mainly due to poor focus. Why the 071 is worse in this respect compared to your DSLR is odd as the sensors are similar regarding pixel size.

Here's an uncalibrated centre crop of a stack of 4 min subs I took with the RedCat 51 for testing (simple stretch in PS) and the stars are pretty sharp. Flat frames are needed due to the blue drop off towards the edges and alternate pixels having a slight green hue if you magnify the image. I use a Lakeside Astro autofocuser with SGP and it autofocuses every 1 degree temp change. With your large initial temp changes it would be autococusing after every sub or so.

Alan

[henry b]

My guess is your ccd is fogging up over time therefore the assumpsion of poor focussing.   Henry b.

[alan potts]

10 hours ago, symmetal said:

Hi Alan,

Sorry to hear you're still unhappy with your 071. I'm not sure what the APT dew setting does but it's worth ticking the Anti dew box in the 071 Ascom Driver to ensure it's on.

This does warm the warm the window in front the sensor and works whether cooling is on or off.

I agree with Adam in that your image problems are mainly due to poor focus. Why the 071 is worse in this respect compared to your DSLR is odd as the sensors are similar regarding pixel size.

Here's an uncalibrated centre crop of a stack of 4 min subs I took with the RedCat 51 for testing (simple stretch in PS) and the stars are pretty sharp. Flat frames are needed due to the blue drop off towards the edges and alternate pixels having a slight green hue if you magnify the image. I use a Lakeside Astro autofocuser with SGP and it autofocuses every 1 degree temp change. With your large initial temp changes it would be autococusing after every sub or so.

Alan

Alan,

I feel Adam is correct in that poor focus is the cause of this. But in my view something could be causing me to make poor focus, I have used this APT system many times where you focus in and out until first visually you see sharpness then aim for the lowest numbers allowing it to settle . At the moment I do not have USB 3, this will change very soon, I am told this affects Live View rate.

I cannot get my head round how I can focus an image of M13 well, without great care I may add, at least I consider the image above sharp. Then after at least 10 attempts during capture cannot get a sharp focus on an image other than the very first ones both nights, re-focus could well have been more than 10 times too I was paranoid by this point. Even the 4-10sec framing shots were sharp with plenty of stars prior to first sub, I didn't save them sadly

I am not saying I always got it right with the Canon but then I never paid it the same degree of attention most times though it way out performed the 071 so far apart from the M13 shot .

I have anti dew ticket where as it wasn't, and I thought this was the issue. I am going to take an image without cooling again as I believe, rightly or wrongly ,this is where I am having a problem and something here is causing this focus issue. I know I am pretty useless at IT stuff but I find it very difficult to believe I am making the same mistake over and over again, it isn't really that difficult to use APT, even for me.

As it stands even with the attempts to gain good focus in the 2nd nights captures, figures in DSS got worse and worse as the night went on starting at a score of 9000+ and ending at 250 and the last refocus so bad it didn't even register, for me this is something more than just my inability to perform focus as I could see stars were sharp even visually as I has a 28 inch screen as well as numbers from the the APT Focus Aid showing Best at .45 on a star and stopping at that the lowest reading. Clearly it will have look right for me to continue to take another sub

Alan   

[alan potts]

Just as an added bit of information I have this morning loaded 12 sets of 25 plus files in DSS from my Canon 40 D just to look at the information DSS gives on them.

Not one set of images tails off in the scoring given by DSS, infact 6 of them go up in places not by much but this is conditions I am sure, but mainly stay the same give or take a bit. Same scope same me focusing same everything all 4 min subs. I am fairly sure i never looked at possible out of focus issues on these sets..

The other thing that crossed my mind, a Canon 40D has a shutter firing every 4 minutes that could jolt the focus, an 071 does not.

This is a Jpeg of the best from 45 subs as far as I could both are stretched to the same degree, just once. Something odd about the top centre edge?

Both shots have just a couple of Darks etc.

 

 

This is a Jpeg from the very worst of the 45 subs if this helps at all this didn't even register in DSS.

 

 

 

Alan

[symmetal]

Alan,

From the two Canon images you've just posted the focus is really very similar to the 071 images you've posted. I think when you get the USB3 module installed and use the bahtinov mask which is coming you should find focussing will be much easier and quicker. 

Alan

[tooth_dr]

@alan potts have you selected the correct threshold in DS to register an appropriate number of stars?

[alan potts]

1 hour ago, tooth_dr said:

@alan potts have you selected the correct threshold in DS to register an appropriate number of stars?

Never moved it always been on the same setting, in any case both Jpeg and the other image were on the settiing, forget exactly what it is but I know why you thought that

 

2 hours ago, symmetal said:

Alan,

From the two Canon images you've just posted the focus is really very similar to the 071 images you've posted. I think when you get the USB3 module installed and use the bahtinov mask which is coming you should find focussing will be much easier and quicker. 

Alan

No they are the 071 subs Alan, I think I am fogging up, Grant suggest maybe cooling too quick, something to look at. Next time I get clear though I am rattling off 8-10 subs of something without cooling on and then I think we will see it is not me focusing. Mask and USB 3 should be with me by the end of the week and the beginning of next, just in time for the Moon.

Alan

[tooth_dr]

But the thing is the setting MUST be changed for each session / different cameras etc. The setting is adjusted to allow say 150 stars to be registered.  I never get scores of 9000 etc but that’s not because my data is poor, but because I don’t register 1000s of stars (and sometimes noise not even stars)

[symmetal]

5 minutes ago, alan potts said:

No they are the 071 subs Alan, I think I am fogging up, Grant suggest maybe cooling too quick, something to look at. Next time I get clear though I am rattling off 8-10 subs of something without cooling on and then I think we will see it is not me focusing. Mask and USB 3 should be with me by the end of the week and the beginning of next, just in time for the Moon.

Alan

Ah! Sorry, misread the post. With fogging you usually get multiple diffraction spikes around bright stars which don't appear in your images, but give it a go with the cooling off to avoid that possibility.

Alan

[steppenwolf]

On 23/09/2019 at 15:12, Adam J said:

Sorry Alan, but when I view that full sized I still see out of focus stars I am 100% sure on this. 

I concur, the focus is indeed out if that helps to resolve the issue 😟.

[alan potts]

32 minutes ago, steppenwolf said:

I concur, the focus is indeed out if that helps to resolve the issue 😟.

We all agree on that Steve, it is why, I took ages focusing more than 6 times in a session, even i don't do a bad job that many times in a 2 hour period, something else is going on here too. Look how tight the M13 image, I didn't take any time over this at all as the Moon was almost full and I only wanted to see if the camera worked, there is no cooling or Cal frames in this image, cooling  I believe is where my problems are.

Alan

[david_taurus83]

Try the original data again but this time adjust the threshold slider in DSS until it only detects 100/150 stars. If its picking up and registering noise as stars it wont remove them.

[alan potts]

12 hours ago, david_taurus83 said:

Try the original data again but this time adjust the threshold slider in DSS until it only detects 100/150 stars. If its picking up and registering noise as stars it wont remove them.

Will try it in the morning, not sure I understand but anything is worth a try. Tried it but went the wrong way with the slider, got scopes of 17,000+ and 3500 stars.

Tried it Dave but it didn't make any difference, 180 down to 30 stars detected. I feel I am going to have to wait for a clear sky and do a few experiments, like captures without cooling and slowing down the cooling. Something is causing me to make these frames out of focus as it is not difficult to use this APT Focus Aid and whilst anyone can make a mistake I don't believe one can make the same mistake so many times in such a short period, when the one thing you are concentrating on is focus, whilst I have had the exact same temperature drops with using the Canon this rarely ever caused a problem for the end result . I think I will also try an image of something lower down to try and reduce or stop possible Crayford focuser slip, which I don't feel is happening, it didn't with the Canon at more than twice the weight, even directly overhead on a few occasions.

Alan

[alan potts]

Well I managed to get out for a few minutes but got very little in the way of data, just 3x 4 minute subs, and how I managed to focus I will never know. I don't feel I did a good job with the patched cloud but I feel it is enough so show the camera works OK  even when I focus it and when cooling is OFF. To me at least this points firmly towards cooling being the problem, so some advice on how to cool maybe nice, as APT steps seem aggressive or there is a problem with the camera itself.

Anyway here is what I got noise and all

 

I know its poor but I am surprised how this has come out for only 12 minutes.

Alan

[symmetal]

Yes, that's much better focus Alan. I did have to replace the desiccant tablets in my new 071 after only a few nights testing when taking flats showed obvious icing on the sensor. It wasn't obvious on my previous night test images but maybe was on the verge of it. Maybe that batch of 071 camera had faulty or damp tablets.

Alan