ASI1600mm cool

[CraigT82]

20 minutes ago, SkyBound said:

Hmmm, not sure you have micro lens on a mono camera, thought that was just colour...!

but I may be wrong

Mono sensors have microlenses to funnel light into the photo site. They'd be nowhere near as sensitive without them. It's the coloured Bayer filters they don't have. 

[Gina]

I shall be putting a couple of Atik 460EX mono CCD cameras up for sale in the appropriate section here before long - just need to get round to it and collect up all the bits that go with the cameras

[sharkmelley]

Another Jellyfish image - same ASI1600MM camera, same bright star artifacts:

https://www.astrobin.com/274760

Mark

[Allinthehead]

I think it ruins the image. Here is my m45 waste of time.

 

[Magnus_e]

18 hours ago, sharkmelley said:

The artifact around bright stars is a diffraction pattern from the regular array of sensor microlenses reflected back onto the sensor from the sensor coverglass which sits a fraction of a millimetre above the microlenses.  There are links to many examples from the ASI1600MM in this Cloudy Nights thread.

http://www.cloudynights.com/topic/555844-pleiadesbright-and-bringing-out-the-microlens-diffraction/

There is nothing the user can do to prevent this, aside from avoiding bright stars.

Mark

I did not see any of those on my Ha data, but it looks like it's affecting my O3.

It does not look as visible on mine, but it's there. At first I thought it was the slightly misty weather making the stars a little bloated.

Not much data on this, so quite dim and noisy.

[Andyb90]

13 hours ago, Allinthehead said:

I think it ruins the image. Here is my m45 waste of time.

 

Post 27 on the CN thread gives some advice on how to reduce the effects.

"You can get rid of the worst of the effects in Photoshop pretty easily.  This was roughly three minutes of work on one of your posted JPG's just by selecting the worst offenders, feathering the selection, applying a color noise reduction filter (twice at 100%), and then adding in a bit of saturation.  Most of the three minutes was actually using a history brush to re-paint the few dim stars that got messed up by the adjustment.  It's not perfect, but it gets rid of most of the rainbow affects."

It seems like very bright stars are generally a pain with DSO Imaging. 

Andy.

[IanL]

On 22/01/2017 at 21:16, SkyBound said:

Hmmm, not sure you have micro lens on a mono camera, thought that was just colour...!

but I may be wrong

You are. CMOS sensors have a lot more circuitry adjacent to the photosites than CCD. The active area can be as small a 25% of each pixel, so microlenses are essential to capture the photons that would otherwise be lost.

[groberts]

I have just taken this camera out for the first time but not yet processed.  Coming form DSLR two immediate problems I found were (i) framing - even turning up gain etc I found it difficult /impossible to see DSO objects in the image, such as I can with DSLR, and (ii) focusing - I'm using APT for now (will go to SGP later) and use a Bahtinov mask + the APT Aid but find the spikes difficult to see etc; I presume I need to refocus for different filters too? 

Thanks, Graham

[Filroden]

1 minute ago, groberts said:

I have just taken this camera out for the first time but not yet processed.  Coming form DSLR two immediate problems I found were (i) framing - even turning up gain etc I found it difficult /impossible to see DSO objects in the image, such as I can with DSLR, and (ii) focusing - I'm using APT for now (will go to SGP later) and use a Bahtinov mask + the APT Aid but find the spikes difficult to see etc; I presume I need to refocus for different filters too? 

Thanks, Graham

I find (using SGPro) that I can take continuous 1s or 2s exposures, software binned to 2x2, which show me enough stars to frame the target. I might also take a single 10s image if the framing is difficult with just stars to see where the DSO is landing within the frame.

Likewise for focusing, I used to choose a very bright star (0 or 1 mag) and use 1s exposures and zoom in on a small area around the star to see the spikes clearer. However, with SGPro, it analyses the star sizes across the whole image and I get better focus by minimising this value rather than use the Bahtinov mask. I now use an auto-focus routine that does this automatically, taking 9 images around the likely point of focus and it calculates the minimum.

Yes, you should refocus for different filters. I see slight differences in the focus values but I cannot detect the effect by eye, so you could focus the L filter, which is where you take the sharpness and rely on the parfocal claim for the RGB (which you only take colour information and is often blurred in processing to reduce noise anyway).

[alcol620]

Hi Folks

Took delivery of the ASI1600 cooled mono a couple of weeks ago from FLO and have hit what I think is a problem. Produced some master flats and hey ho, lots of blobs, lines etc. on the master flat when stretched in Pixinsight.

To try to narrow down where these blobs etc were coming from I rotated the camera (only the camera and nothing else) and took another series of flats and produced a second master. The image of the 2 master flats is attached, the one on the right has the camera only rotated about 90 degrees. Most of the blobs are in the same place and suggests, unless I am mistaken that their origins are inside the camera. I have also attached an image of the master flats through each of the filters RGB, Ha and OIII.

As the camera was brand new a couple of weeks ago, the debris causing the marks on the image must have been a left over from manufacture?

Any one else have this problem or have any comments on the above?

Thanks for your feedback

[Guest]

24 minutes ago, alcol620 said:

Hi Folks

Took delivery of the ASI1600 cooled mono a couple of weeks ago from FLO and have hit what I think is a problem. Produced some master flats and hey ho, lots of blobs, lines etc. on the master flat when stretched in Pixinsight.

To try to narrow down where these blobs etc were coming from I rotated the camera (only the camera and nothing else) and took another series of flats and produced a second master. The image of the 2 master flats is attached, the one on the right has the camera only rotated about 90 degrees. Most of the blobs are in the same place and suggests, unless I am mistaken that their origins are inside the camera. I have also attached an image of the master flats through each of the filters RGB, Ha and OIII.

camera warand new a couple of weeks ago, the debris causing the marks on the image must have been a left over from manufacture?

Any one else have this problem or have any comments on the above?

Thanks for your feedback

I think the lines are moisture / frost.

I've had that and as it cools down they start to disappear :-)

David

 

[groberts]

4 hours ago, Filroden said:

I find (using SGPro) that I can take continuous 1s or 2s exposures, software binned to 2x2, which show me enough stars to frame the target. I might also take a single 10s image if the framing is difficult with just stars to see where the DSO is landing within the frame.

Likewise for focusing, I used to choose a very bright star (0 or 1 mag) and use 1s exposures and zoom in on a small area around the star to see the spikes clearer. However, with SGPro, it analyses the star sizes across the whole image and I get better focus by minimising this value rather than use the Bahtinov mask. I now use an auto-focus routine that does this automatically, taking 9 images around the likely point of focus and it calculates the minimum.

Yes, you should refocus for different filters. I see slight differences in the focus values but I cannot detect the effect by eye, so you could focus the L filter, which is where you take the sharpness and rely on the parfocal claim for the RGB (which you only take colour information and is often blurred in processing to reduce noise anyway).

Thanks Ken, does the binning help then?  I tried the Rosette and could in fact make out where it was from the stars but even with higher gain + longer exposures  etc using L, R or Ha didn't get anything of the nebula for framing - unlike my modded DSLR where it shows up well on say +20secs.  Sounds like I need to move on to SGP sooner rather than later; I've had APT for two years but this is the first time I've used it - probably not as sophisticated as SGP but was easy to pick up just to test & play with the ZWO camera and EFW and the support from Ivo is excellent.    

[alcol620]

6 minutes ago, David_L said:

I think the lines are moisture / frost.

I've had that and as it cools down they start to disappear :-)

David

 

Hi David

Although the 5 images through the filters may be frost, because they were taken to produce mast flats at imaging temperatures. The 2 images, one with the camera rotated, were taken at room temperature and the marks were still there, albeit a bit fainter

[alcol620]

5 minutes ago, groberts said:

Thanks Ken, does the binning help then?  I tried the Rosette and could in fact make out where it was from the stars but even with higher gain + longer exposures  etc using L, R or Ha didn't get anything of the nebula for framing - unlike my modded DSLR where it shows up well on say +20secs.  Sounds like I need to move on to SGP sooner rather than later; I've had APT for two years but this is the first time I've used it - probably not as sophisticated as SGP but was easy to pick up just to test & play with the ZWO camera and EFW and the support from Ivo is excellent.    

Hi Graham

Use Plate solving in APT and it will get you to exactly the same spot night after night

[Filroden]

13 minutes ago, groberts said:

Thanks Ken, does the binning help then?

Yes, you're effectively gathering 4x the light per pixel at the expense of resolution (which isn't needed for framing). You could go to 3x3 or even 4x4 binning. I find I can see the Rosette clearly in about 30 seconds, even in Ha (again, SGPro applies an automatic stretch to the image so it's quite obvious).

[alcol620]

5 hours ago, groberts said:

I have just taken this camera out for the first time but not yet processed.  Coming form DSLR two immediate problems I found were (i) framing - even turning up gain etc I found it difficult /impossible to see DSO objects in the image, such as I can with DSLR, and (ii) focusing - I'm using APT for now (will go to SGP later) and use a Bahtinov mask + the APT Aid but find the spikes difficult to see etc; I presume I need to refocus for different filters too? 

Thanks, Graham

Graham

You can also use the APT histogram, under tools. this will stretch what ever image you have. Stick with APT it will do everything you want to do, but like everything it take time. Also under Camera, set up a Focusing/Framing Plan fro each filter. I use  3s exposures bin 1x1 pause 3 (to enable a move of the focuser) and say 50 images.

[groberts]

OK thanks guys, love the idea of plate solving but at the moment it's one step at a time.  I like to keep it simple and, insofar as possible, manual and as close to what I'm familiar with.  In this regard the use of binning and the stretching sounds helpful - will give it a try.     

[Guest]

1 hour ago, alcol620 said:

Hi David

Although the 5 images through the filters may be frost, because they were taken to produce mast flats at imaging temperatures. The 2 images, one with the camera rotated, were taken at room temperature and the marks were still there, albeit a bit fainter

Ah! I see - yes, it was probably frost forming on the fault - is it a hair or group of hairs?

I used to open my QHY8 and clean the sensor no problem, doesn't hurt it, but I'm not sure about this system (CMOS)

David

[alcol620]

1 minute ago, David_L said:

Ah! I see - yes, it was probably frost forming on the fault - is it a hair or group of hairs?

I used to open my QHY8 and clean the sensor no problem, doesn't hurt it, but I'm not sure about this system (CMOS)

David

Hairs from China as the camera is only 2 weeks old  lol

[Guest]

5 hours ago, alcol620 said:

Hairs from China as the camera is only 2 weeks old  lol

:-) I had one on my QHY8 when I got it new from China, that's when I learned how to clean the sensor - just a suggestion but probably too uniform to be hairs

[trev27]

18 hours ago, groberts said:

Thanks Ken, does the binning help then?  I tried the Rosette and could in fact make out where it was from the stars but even with higher gain + longer exposures  etc using L, R or Ha didn't get anything of the nebula for framing - unlike my modded DSLR where it shows up well on say +20secs.  Sounds like I need to move on to SGP sooner rather than later; I've had APT for two years but this is the first time I've used it - probably not as sophisticated as SGP but was easy to pick up just to test & play with the ZWO camera and EFW and the support from Ivo is excellent.    

@groberts. If you set "Auto-Str L" on on the historgram window in apt you should see the rosette in a few seconds - I think it was appearing in 3 or 4 seconds for me with this camera at F5 or so.

[groberts]

OK thanks Trev will look into that too.

[alcol620]

On 1/24/2017 at 14:59, alcol620 said:

Hi David

Although the 5 images through the filters may be frost, because they were taken to produce mast flats at imaging temperatures. The 2 images, one with the camera rotated, were taken at room temperature and the marks were still there, albeit a bit fainter

FLO on the ball as usual, agreed that the camera be replaced. Great customer service.

[Allinthehead]

Now this is a little odd. I received my William Optics star 71 on Thursday and got first light last night. If you look at Alnitak the odd diffraction pattern that was ever present on the brightest stars with the ed 80 are no more. This image is 20 minutes in 30 second subs gain 399 offset 15. I must try a 120 sub next clear night as perhaps the shorter subs are the reason, however i did get them at 50 seconds with the ed 80.

I had correspondence with someone who got the artifact with a filter wheel in place but not with just the filter suggesting a spacing issue rather than the sensor cover. 

Richard.

[Andyb90]

3 hours ago, Allinthehead said:

Now this is a little odd. I received my William Optics star 71 on Thursday and got first light last night. If you look at Alnitak the odd diffraction pattern that was ever present on the brightest stars with the ed 80 are no more. This image is 20 minutes in 30 second subs gain 399 offset 15. I must try a 120 sub next clear night as perhaps the shorter subs are the reason, however i did get them at 50 seconds with the ed 80.

I had correspondence with someone who got the artifact with a filter wheel in place but not with just the filter suggesting a spacing issue rather than the sensor cover. 

Richard.

That's interesting. I was just reading a thread on CN for a new QHY mono camera. A similar artifact has been described and one poster has said it is due to spacing between filter and sensor.

http://www.cloudynights.com/topic/552285-qhy163-mono-first-shots/page-3

Do you know the approx distance from filter to sensor with your Star 71?

Andy.