ASI 1600 and Microlensing

[Rodd]

2 minutes ago, ollypenrice said:

This 60 mp 35mm camera is, on paper, what the FSQ106 has been waiting for. I hope it works without microlensing or other issues and if it does I don't see it being resistible! But CMOS cameras have their share of issues so I won't be an early adopter.

To be honest I love working with the old Atik 11000 camera. I've said before that the numbers are lousy - QE and resolution at 530mm - but the data is so sweet. Lovely stars, lovely star colour. 3.5"PP doesn't resolve the finest details but stars are absolutely not blocky. This is a fallacy and the 106/KAF1100 has more APODS than you can shake a stick at.

Olly

The real question is whether the same astrophotographers using different cameras would get those APODs.  I'd say probably.  But I am not disagreeing with what you say.  However, I really like the resolution I get with small pixels and the FSQ 106 at F3--it provides for multiple images (cropping sections can stand on their own).  The same would be true with any of the CCDs with small pixels--just not with the expansive FOV.  But I agree-I won't be an early buyer of the 60mp (or even the 100mp to come out in 2020).  I have to use the ASI 1600 with the FSQ at f3--the STT-8300's self guiding filter wheel eats up too much back focus for that reducer.  That is why I got teh camera, so no harm I guess.  i just wanted to see how it would resolve using longer focal lengths.  I have to say, seeing my limiting factor, so I see no resolution improvement over the STT-8300 with the TOA 130.

Rodd

[kirkster501]

Hmmm, making me think that I'll keep CMOS for the moon and planets and stay with CCD - what I know - for deep sky.

Now, anyone flogging a QSI 683? 😂

[Rodd]

20 minutes ago, kirkster501 said:

Hmmm, making me think that I'll keep CMOS for the moon and planets and stay with CCD - what I know - for deep sky.

Now, anyone flogging a QSI 683? 😂

To be honest--I got the ASI 1600 because it was affordable.  if I had had 5-7,000 to spend on a camera I would have gotten  a big CCD.--Then again, without small pixels I would not want to shoot at a FL of 318mm-so i would not have bought the FSQ.  Its all a big ball of knotted fishing line.  As there isn't one perfect scope for all targets, there is not one perfect camera for all scopes.  The ASI 1600 works tremendously well with the FSQ 106 and .6x reducer--so that is where I will use it from now on.  The STT-8300 worked a charm with my other scopes.

Rodd

PS  And I would like to add that the microlensing artifacts do not only show around the very bright stars.  i have noticed them around 2stars near M13, and the  star in the Witches Broom (Western Vail).  None of these are 1st, 2nd, , 3rd or 4th mag stars (I don't think.  Could be wrong about 4th).  Just checked--it is a 4th mag star.  that's pretty bad to not be able to image 4th mag stars.  And I use Astrodons.

Edited October 16, 2019 by Rodd

[newbie alert]

4 hours ago, ollypenrice said:

This 60 mp 35mm camera is, on paper, what the FSQ106 has been waiting for. I hope it works without microlensing or other issues and if it does I don't see it being resistible! But CMOS cameras have their share of issues so I won't be an early adopter.

To be honest I love working with the old Atik 11000 camera. I've said before that the numbers are lousy - QE and resolution at 530mm - but the data is so sweet. Lovely stars, lovely star colour. 3.5"PP doesn't resolve the finest details but stars are absolutely not blocky. This is a fallacy and the 106/KAF1100 has more APODS than you can shake a stick at.

Olly

Yes I agree with you Olly, I'm continuing to hear that you can't undersample as you get blocky stars..when I show them your image of the witches head at 3.5 pp it all goes strangely quiet..

Then they say it again a few weeks later!!

[newbie alert]

4 hours ago, ollypenrice said:

This 60 mp 35mm camera is, on paper, what the FSQ106 has been waiting for. I hope it works without microlensing or other issues and if it does I don't see it being resistible! But CMOS cameras have their share of issues so I won't be an early adopter.

To be honest I love working with the old Atik 11000 camera. I've said before that the numbers are lousy - QE and resolution at 530mm - but the data is so sweet. Lovely stars, lovely star colour. 3.5"PP doesn't resolve the finest details but stars are absolutely not blocky. This is a fallacy and the 106/KAF1100 has more APODS than you can shake a stick at.

Olly

Yes I agree with you Olly, I'm continuing to hear that you can't undersample as you get blocky stars..when I show them your image of the witches head at 3.5 pp it all goes strangely quiet..

Then they say it again a few weeks later!!

[Rodd]

Just now, newbie alert said:

Yes I agree with you Olly, I'm continuing to hear that you can't undersample as you get blocky stars..when I show them your image of the witches head at 3.5 pp it all goes strangely quiet..

Then they say it again a few weeks later!!

A minor point....I believe that image was down sampled--or whatever he did to reduce the size when full resolution viewing is initiated.  i think if that step wasn't taken you would see more of the star effect than you do now.

Rodd

[newbie alert]

9 minutes ago, Rodd said:

A minor point....I believe that image was down sampled--or whatever he did to reduce the size when full resolution viewing is initiated.  i think if that step wasn't taken you would see more of the star effect than you do now.

Rodd

First thing I do is zoom in..never seen blocky stars at my own 3.0 pp..  but then again I'm never going to get it printed A4/3 size..

[ollypenrice]

26 minutes ago, newbie alert said:

Yes I agree with you Olly, I'm continuing to hear that you can't undersample as you get blocky stars..when I show them your image of the witches head at 3.5 pp it all goes strangely quiet..

Then they say it again a few weeks later!!

Yes, the chip's an oldie but a goodie... It also got runner up slot in the APOTY comp with Orion.

Olly

[ollypenrice]

27 minutes ago, Rodd said:

A minor point....I believe that image was down sampled--or whatever he did to reduce the size when full resolution viewing is initiated.  i think if that step wasn't taken you would see more of the star effect than you do now.

Rodd

I'm in hospital at the moment (completely mended, it seems!) but I'll put a full size up when I can. Plenty of my 11meg/106 images have been posted with only a tiny down sampling to allow for internet and JPEG effects.

Olly

[Rodd]

1 minute ago, ollypenrice said:

I'm in hospital at the moment (completely mended, it seems!) but I'll put a full size up when I can. Plenty of my 11meg/106 images have been posted with only a tiny down sampling to allow for internet and JPEG effects.

Olly

Sorry to hear.....I hope its nothing too serious.  I hope you don't have to stay i the hospital too long. 

Rodd

[ollypenrice]

7 minutes ago, Rodd said:

Sorry to hear.....I hope its nothing too serious.  I hope you don't have to stay i the hospital too long. 

Rodd

Thanks Rodd. All is well and home tomorrow.

Olly

[Xplode]

On 15/10/2019 at 14:33, Rodd said:

A lot has been written about microlensing causing artifacts around bright stars when using the ASI 1600.  I have noticed several things about this that I would like to add to the discussion.

1) The effect seems to be getting worse over time.  Not sure this is even possible, or real--but it seems that way.  It is not something I noticed up until recently--then again maybe there were not bright enough stars in the FOV.

2) I think the artifact from microlensing--if that is what it even is-may be related to resolution (pixel scale).  I say this because I have imaged the Horsehead Nebula with the FSQ 106 at a pixel scale of 2.46 arcsec/pix and the TOA 130 at a resolution of 0.78 arcsec/pix.  There is no sign of a microlensing artifact around Alnitak at a resolution of 2.46, but there is a severe microlensing artifact around Alnitak at 0.78 arcsec/pix.   I do not think it is the TOA 130 OTA, as stars in general are quite nice. 

Any ideas?  I have images to show as examples but it will have to wait until I get home to post (later tonight). 

Thanks,

Rodd

I've used the QHY163 which has the same sensor with a TOA150 with 645 flattener and haven't seen any microlensing so it's weird that you get microlensing with a TOA130.
Right now the setup has an 1.6x extender that i can test with to see if f ratio/pixel scale makes a difference. 
Later i could test with a FSQ130 without and with 645 reducer

[Rodd]

1 minute ago, ollypenrice said:

Thanks Rodd. All is well and home tomorrow.

Olly

But it will be clear tonight, doc!!!!!!

[Rodd]

2 minutes ago, Xplode said:

I've used the QHY163 which has the same sensor with a TOA150 with 645 flattener and haven't seen any microlensing so it's weird that you get microlensing with a TOA130.
Right now the setup has an 1.6x extender that i can test with to see if f ratio/pixel scale makes a difference. 
Later i could test with a FSQ130 without and with 645 reducer

I don't think it could be the scope as with the STT-8300 things are perfect.  in fact, things are perfect with the TOA 130 and the ASI 1600 except for 4th-1st Mag stars.   Maybe its a gain-exposure length thing.  Maybe I need to expose less.  Maybe my sky is hazy and that contributes.  Who knows.  I will be switch to the FSQ 106 as soon as I finish my current project....mayb I should try the TOA 130 with the .7x reducer first though, to see if that helps

Rodd

[vlaiv]

Important part of the "equation" of microlens artifact seems to be missing, so I'll mention it for all who want to get to bottom of this.

Filter type and spacing.

I don't think that microlens effects exists on its own. It needs some sort of reflective surface for interference effects to kick in. I've heard the explanation that sensor cover window is not AR coated (not chamber cover window, but sensor - much closer to sensor surface) - but I don't necessarily buy into it. If it were in fact true microlens effect would be fairly similar in size and only impacted by speed of the scope and wavelength. I'm not saying that sensor cover window is not playing a part - I'm just saying that I think it is due to combination of multiple reflective surfaces, including any filters used.

Many people use 1.25" filters with ASI1600 and that means placing them fairly close to sensor. Lower scopes allow for placing them further away, Maybe general filter distance plays a part and is partly responsible for fast scopes - no artifact / slow scopes - artifact phenomena.

 

[Rodd]

3 minutes ago, vlaiv said:

Important part of the "equation" of microlens artifact seems to be missing, so I'll mention it for all who want to get to bottom of this.

Filter type and spacing.

I don't think that microlens effects exists on its own. It needs some sort of reflective surface for interference effects to kick in. I've heard the explanation that sensor cover window is not AR coated (not chamber cover window, but sensor - much closer to sensor surface) - but I don't necessarily buy into it. If it were in fact true microlens effect would be fairly similar in size and only impacted by speed of the scope and wavelength. I'm not saying that sensor cover window is not playing a part - I'm just saying that I think it is due to combination of multiple reflective surfaces, including any filters used.

Many people use 1.25" filters with ASI1600 and that means placing them fairly close to sensor. Lower scopes allow for placing them further away, Maybe general filter distance plays a part and is partly responsible for fast scopes - no artifact / slow scopes - artifact phenomena.

 

Maybe....but that's actually bad news if its true because changing the filter distance is problematic.  Not easilly done.

Rodd

[Xplode]

The way the filters are mounted could also play a part.
On my QHY163 i'm using 36mm Baader filters mounted the "correct" way (arrow towards the scope)

Edited October 16, 2019 by Xplode

[Rodd]

3 minutes ago, Xplode said:

The way the filters are mounted could also play a part.
On my QHY163 i'm using 36mm Baader filters mounted the "correct" way (arrow towards the scope)

have no idea what the arrow is--My Astrodons are not equipped with an arrow--neither are my Baader 36mm for that matter

[Xplode]

Your Baader filters must be old or  you haven't looked hard enough?
All unmounted Baader filters i've seen for the last 4 years has arrows on them to help mount them the correct way

[Rodd]

3 minutes ago, Xplode said:

Your Baader filters must be old or  you haven't looked hard enough?
All unmounted Baader filters i've seen for the last 4 years has arrows on them to help mount them the correct way

Well--no matter, I use the Astrodons with the ASI 1600.  the Baaders are not currently being used.  

[gorann]

Not sure what cameras you have in stock Rodd but I found I can solve the microlensing problem I sometimes have with my ASI1600 on bright stars by replacing it with a bit of ASI071 (OSC) data to the bright star. For bright stars you just need a few minutes of data to do this.

Edited October 16, 2019 by gorann

[JamesF]

I know that the starburst effect on the 183 sensor can be mostly calibrated out, as can the glow on the 174 sensor, and that if you're lucky the whole microlensing issue won't be a problem for you on the ASI1600 and similar cameras, but I do still feel quite disappointed that these problems exist in the first place in cameras intended for astronomy.  I realise the sensors weren't created with a view to astronomy use, but I don't think that's really the point.

I'd really quite like another deep sky camera at the moment, but I really don't want the harrassment of finding, say, the 1600MM doesn't work for me, or of trying to clean up the effects of significant artefacts in images that I feel shouldn't be there to start with.

Fortunately I'm in the unenviable position of having spent the money on a barn so I can't afford one and I can just sit back and see what the future brings...

James

[spillage]

7 minutes ago, JamesF said:

I really don't want the harrassment of finding, say, the 1600MM doesn't work for me

Your just up the road from me. So if at any point your really thinking about it give me a shout and you can you always give my 1600 a run one night on your kit. I find that the ed80 suffers more than the quattro or 130pds.

[Laurin Dave]

7 minutes ago, spillage said:

I find that the ed80 suffers more than the quattro or 130pds.

Same as me and Rodd.. slower scopes worse, also for me changing from zwo to Astrodon filters had no effect on the microlensing.  

Pleased to hear you’re on the mend Olly

Dave

[jjosefsen]

Does this lensing effect happen due to something on the sensor or is it the front glas?