The Charlie Bates Solar Astronomy Project is proudly sponsored by the following fine companies:
ImageImageImageImage
Image
Image
Transit of Mercury in the Spicule Layer. Phil took this great image with his Quantum 6 Scope, Solar Spectrum etalon and PGR Camera.

Welcome to Solar Chat! The best forum for Solar Astronomy
Moving forward from solar cycle 24 to 25

"Ghosts in the Machine"

this is the main message area for anything solar :)
Post Reply
User avatar
Merlin66
Librarian
Librarian
Posts: 3369
Joined: Tue Dec 13, 2011 1:23 pm
Location: St Leonards, Australia
Contact:

"Ghosts in the Machine"

Post by Merlin66 » Sun Nov 24, 2019 10:44 pm

A couple of weeks ago I noticed a very small, and tight "Dust Bunnie" - a mote on the CCD glass of my ASI 1600MM.
I use an ED80 (f7.5) with the x2.5 PM giving an imaging beam of F18.75 when imaging Ha.

Cut to the chase....I set up my ST80 with a plastic bag to get some easier flats ( f 12.5) while cleaning the front sealing plate and the CCD cover plate.
I was using IPA and KIMTECH wipes....
What a frustrating journey!!!! I found after many (>20) attempts - don't blow on the surfaces! This just seemed to add more small motes...

What I did find "interesting" was the fact that if the PM was removed and the flats taken at f5 - they were perfect!!!!!!
Push the f ratio up (yes, I did try different Barlows and the PM with similar results) and the motes and Dust Bunnies reappeared.

I can't understand why?

Has anyone experienced the same phenomena????
"Astronomical Spectroscopy - The Final Frontier" - to boldly go where few amateurs have gone before
https://groups.yahoo.com/neo/groups/ast ... scopy/info
"Astronomical Spectroscopy for Amateurs" and
"Imaging Sunlight - using a digital spectroheliograph" - Springer

User avatar
rsfoto
Almost There...
Almost There...
Posts: 944
Joined: Mon Jun 18, 2012 8:30 pm
Location: San Luis Potosi, México

Re: "Ghosts in the Machine"

Post by rsfoto » Sun Nov 24, 2019 11:27 pm

Merlin66 wrote:
Sun Nov 24, 2019 10:44 pm
A couple of weeks ago I noticed a very small, and tight "Dust Bunnie" - a mote on the CCD glass of my ASI 1600MM.
I use an ED80 (f7.5) with the x2.5 PM giving an imaging beam of F18.75 when imaging Ha.

Cut to the chase....I set up my ST80 with a plastic bag to get some easier flats ( f 12.5) while cleaning the front sealing plate and the CCD cover plate.
I was using IPA and KIMTECH wipes....
What a frustrating journey!!!! I found after many (>20) attempts - don't blow on the surfaces! This just seemed to add more small motes...

What I did find "interesting" was the fact that if the PM was removed and the flats taken at f5 - they were perfect!!!!!!
Push the f ratio up (yes, I did try different Barlows and the PM with similar results) and the motes and Dust Bunnies reappeared.

I can't understand why?

Has anyone experienced the same phenomena????
Hi,
I can't understand why?

Has anyone experienced the same phenomena????
That is normal as when you stop down eg increase from f/5 to f/12.5 the depth of field changes.

Low f/number shallow depth of field. High f/number deep depth of field ...

Rainer
regards Rainer

Observatorio Real de 14 San Luis Potosi Mexico

User avatar
Merlin66
Librarian
Librarian
Posts: 3369
Joined: Tue Dec 13, 2011 1:23 pm
Location: St Leonards, Australia
Contact:

Re: "Ghosts in the Machine"

Post by Merlin66 » Mon Nov 25, 2019 4:00 am

Rainer,
Hmmmm
OK, but why would that make motes on the surface of the CCD chip more visible????
Ken
"Astronomical Spectroscopy - The Final Frontier" - to boldly go where few amateurs have gone before
https://groups.yahoo.com/neo/groups/ast ... scopy/info
"Astronomical Spectroscopy for Amateurs" and
"Imaging Sunlight - using a digital spectroheliograph" - Springer

User avatar
rsfoto
Almost There...
Almost There...
Posts: 944
Joined: Mon Jun 18, 2012 8:30 pm
Location: San Luis Potosi, México

Re: "Ghosts in the Machine"

Post by rsfoto » Mon Nov 25, 2019 4:04 am

Merlin66 wrote:
Mon Nov 25, 2019 4:00 am
Rainer,
Hmmmm
OK, but why would that make motes on the surface of the CCD chip more visible????
Ken
Hi Ken,

Because they are better in focus

Some images of all scenarios would be nice.

Rainer
regards Rainer

Observatorio Real de 14 San Luis Potosi Mexico

User avatar
pedro
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 7252
Joined: Sun May 01, 2016 8:26 pm
Location: Portugal
Contact:

Re: "Ghosts in the Machine"

Post by pedro » Mon Nov 25, 2019 11:46 am

Hi Ken

I also have dust bunnies in CCD/CMOS cameras. These are much more evident when I use powermates or barlows for HR imaging.

I never use conventional flats, only artificial flats sometimes to correct uneven mosaics.

In one of my cameras I have two annoying bust bunnies that I am unable to clean. My feeling is that they are inside the camera (inside the window)

User avatar
Carbon60
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 6347
Joined: Wed Mar 07, 2012 12:33 pm
Location: Lancashire, UK

Re: "Ghosts in the Machine"

Post by Carbon60 » Mon Nov 25, 2019 8:57 pm

Ken,

I regularly clean my CCD sensors. More accurately, I regularly clean the cover glass of my sensors, since we don't actually ever touch the sensor itself. I definitely see the same issue. My 5x PM certainly shows more tiny spots than my 2.5x PM and this shows more than the natural focal ratio of the scope. As I think I've mentioned before, it can take multiple passes with the air duster, sometimes with a blast of anti-static and sometimes with a wipe from a piece of lint-free cloth taped over the blunt end of a pencil with an eraser to protect from scratching the glass. As you say, it can be frustrating, with a subsequent 'clean' depositing more dust motes than previous one, but perseverance pays off and in the end (after multiple rounds) the sensor can be made to be spotless.....literally.

BTW, I do this in my living room using a Celestron Nexstar C4, focusing on an illuminated wall across the way to provide a blank screen. No need for daylight or a plastic bag.

Stu.
Lunt LS60THa B1200 PTFT
150mm H-alpha Solar telescope with Lunt35 mod
DMK41, Basler acA1920-155
NEQ6 Pro-mount
Fluxgate Magnetometers (1s and 150s Cadence)
More images at http://www.flickr.com/photos/solarcarbon60/

User avatar
Merlin66
Librarian
Librarian
Posts: 3369
Joined: Tue Dec 13, 2011 1:23 pm
Location: St Leonards, Australia
Contact:

Re: "Ghosts in the Machine"

Post by Merlin66 » Mon Nov 25, 2019 10:54 pm

I made a “wiper” using a thin plastic card, cut to a 14mm wide edge.
Wrapped in four folds of the KimWipe and sprayed liberally with IPA.
One wipe across the CCD cover....dump the KimWipe.
Repeat until success.
I found brushes and blowers just added more motes!!
Used the same technique on the inner and outer surface of the protection window.
A real PITA.
"Astronomical Spectroscopy - The Final Frontier" - to boldly go where few amateurs have gone before
https://groups.yahoo.com/neo/groups/ast ... scopy/info
"Astronomical Spectroscopy for Amateurs" and
"Imaging Sunlight - using a digital spectroheliograph" - Springer

User avatar
Martin_S
Ohhhhhh My!
Ohhhhhh My!
Posts: 105
Joined: Sat Mar 16, 2019 12:34 am
Location: Brisbane , Australia

Re: "Ghosts in the Machine"

Post by Martin_S » Tue Nov 26, 2019 5:17 am

Ken , have you thought of setting up in the bathroom in the evening after a shower with the windows closed the, moist air will cool down and drop to the floor taking the dust particles with it. Giving you a dust free environment to work in.

Martin

User avatar
Merlin66
Librarian
Librarian
Posts: 3369
Joined: Tue Dec 13, 2011 1:23 pm
Location: St Leonards, Australia
Contact:

Re: "Ghosts in the Machine"

Post by Merlin66 » Tue Nov 26, 2019 5:24 am

Martin,
Yes, tried all that......and fine water spraying the work area before starting....
Didn't make any difference to the small motes on the CCD cover.....
"Astronomical Spectroscopy - The Final Frontier" - to boldly go where few amateurs have gone before
https://groups.yahoo.com/neo/groups/ast ... scopy/info
"Astronomical Spectroscopy for Amateurs" and
"Imaging Sunlight - using a digital spectroheliograph" - Springer

User avatar
marktownley
Librarian
Librarian
Posts: 26453
Joined: Tue Oct 18, 2011 5:27 pm
Location: Brierley Hills, UK
Contact:

Re: "Ghosts in the Machine"

Post by marktownley » Tue Nov 26, 2019 6:07 am

Always one for a different approach. Do away with the dust sensor glass. I did this with my PGR IMX249 camera, as there was a 'blob' beneath the sensor and on the chip itself. Cleaned this away with the usual methods as above, but never replaced the cover slip. Never had any issues with this and any dust on the CMOS chip I just cleaned away...
Image
http://brierleyhillsolar.blogspot.co.uk/
Solar images, a collection of all the most up to date live solar data on the web, imaging & processing tutorials - please take a look!

User avatar
Merlin66
Librarian
Librarian
Posts: 3369
Joined: Tue Dec 13, 2011 1:23 pm
Location: St Leonards, Australia
Contact:

Re: "Ghosts in the Machine"

Post by Merlin66 » Tue Nov 26, 2019 6:58 am

Mark,
I well understand that approach !!!
After having spent MUCH time cleaning the sensor cover....
I found cleaning (both sides) of the front cover (and fitting/ refitting the O ring!!) just caused more motes to appear on the CCD cover.
Very very frustrating.
Ken
"Astronomical Spectroscopy - The Final Frontier" - to boldly go where few amateurs have gone before
https://groups.yahoo.com/neo/groups/ast ... scopy/info
"Astronomical Spectroscopy for Amateurs" and
"Imaging Sunlight - using a digital spectroheliograph" - Springer

User avatar
Carbon60
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 6347
Joined: Wed Mar 07, 2012 12:33 pm
Location: Lancashire, UK

Re: "Ghosts in the Machine"

Post by Carbon60 » Tue Nov 26, 2019 7:29 am

marktownley wrote:
Tue Nov 26, 2019 6:07 am
Always one for a different approach. Do away with the dust sensor glass. I did this with my PGR IMX249 camera, as there was a 'blob' beneath the sensor and on the chip itself. Cleaned this away with the usual methods as above, but never replaced the cover slip. Never had any issues with this and any dust on the CMOS chip I just cleaned away...
Interesting, Mark. Did removing the sensor glass have any effect on eliminating Newton’s rings?

Stu.
Lunt LS60THa B1200 PTFT
150mm H-alpha Solar telescope with Lunt35 mod
DMK41, Basler acA1920-155
NEQ6 Pro-mount
Fluxgate Magnetometers (1s and 150s Cadence)
More images at http://www.flickr.com/photos/solarcarbon60/

User avatar
Carbon60
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 6347
Joined: Wed Mar 07, 2012 12:33 pm
Location: Lancashire, UK

Re: "Ghosts in the Machine"

Post by Carbon60 » Tue Nov 26, 2019 7:31 am

Merlin66 wrote:
Mon Nov 25, 2019 10:54 pm
I made a “wiper” using a thin plastic card, cut to a 14mm wide edge.
Wrapped in four folds of the KimWipe and sprayed liberally with IPA.
One wipe across the CCD cover....dump the KimWipe.
Repeat until success.
I found brushes and blowers just added more motes!!
Used the same technique on the inner and outer surface of the protection window.
A real PITA.
Interesting, Ken. I’ll give that a try.

Stu.
Lunt LS60THa B1200 PTFT
150mm H-alpha Solar telescope with Lunt35 mod
DMK41, Basler acA1920-155
NEQ6 Pro-mount
Fluxgate Magnetometers (1s and 150s Cadence)
More images at http://www.flickr.com/photos/solarcarbon60/

User avatar
Merlin66
Librarian
Librarian
Posts: 3369
Joined: Tue Dec 13, 2011 1:23 pm
Location: St Leonards, Australia
Contact:

Re: "Ghosts in the Machine"

Post by Merlin66 » Tue Nov 26, 2019 7:37 am

Stu,
I think Mark is saying that the front sealing glass plate in front of the CCD cover plate was not replaced.
The NR are generated from the CCD cover plate not the protective front cover plate.
"Astronomical Spectroscopy - The Final Frontier" - to boldly go where few amateurs have gone before
https://groups.yahoo.com/neo/groups/ast ... scopy/info
"Astronomical Spectroscopy for Amateurs" and
"Imaging Sunlight - using a digital spectroheliograph" - Springer

User avatar
eroel
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 4811
Joined: Mon Dec 19, 2011 10:45 pm
Location: México D.F.

Re: "Ghosts in the Machine"

Post by eroel » Tue Nov 26, 2019 5:12 pm

Ken:
I think that we all have had the same problem with motes and Barlows and with longer final focal lengths etc, what I have done since long, is to have an air compressor at the observatories, fitted with double air filters and dehumidifiers, and I do not use more than 20lbs. of air pressure.
Every time that I take out a camera, I blow some clean air to the chip window and after that I use the old antistatic gun, (was used for vinyl music records) then give it another blow of air with the window of the chip facing down, this has kept my cameras very clean, though there are some times that I take off the reducer or a filter from the camera nose and that is when one gets those molesting motes. BTW, after using the camera I blow air again and keep it in closed fitted to a small size plastic Tupperware.
If I can not blow the motes out, then what I do is to use an old formula that I have made since I started up doing imaging, it is 50% pure isopropyl alcohol and 50 % of distilled water, with a drop of liquid dish cleaner ((I use an little glass container with a spray), moist one side of a Qtip or equivalent and pass it on the protective window of the chip, using a very light passes, then with the dry other side of the tip I pass it to dry it, then the usual air blow without the antistatic gun and then after the static gun. This has kept my chip windows very clean.
The solution takes care of some oily motes that are stubborn, if they keep on, then I use a Qtip with pure alcohol and that takes care of them.
For bigger window chips I have used a wiper made of a presentation card (cardboard or plastic), I fold some Kleenex or equivalent wrap and moist it with the cleaning solution, the air, the antistatic gun and that is all.
Best regards,
Eric.

User avatar
marktownley
Librarian
Librarian
Posts: 26453
Joined: Tue Oct 18, 2011 5:27 pm
Location: Brierley Hills, UK
Contact:

Re: "Ghosts in the Machine"

Post by marktownley » Tue Nov 26, 2019 6:41 pm

Carbon60 wrote:
Tue Nov 26, 2019 7:29 am
marktownley wrote:
Tue Nov 26, 2019 6:07 am
Always one for a different approach. Do away with the dust sensor glass. I did this with my PGR IMX249 camera, as there was a 'blob' beneath the sensor and on the chip itself. Cleaned this away with the usual methods as above, but never replaced the cover slip. Never had any issues with this and any dust on the CMOS chip I just cleaned away...
Interesting, Mark. Did removing the sensor glass have any effect on eliminating Newton’s rings?

Stu.
None what so ever sadly!
Image
http://brierleyhillsolar.blogspot.co.uk/
Solar images, a collection of all the most up to date live solar data on the web, imaging & processing tutorials - please take a look!

User avatar
Carbon60
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 6347
Joined: Wed Mar 07, 2012 12:33 pm
Location: Lancashire, UK

Re: "Ghosts in the Machine"

Post by Carbon60 » Tue Nov 26, 2019 7:35 pm

Merlin66 wrote:
Tue Nov 26, 2019 7:37 am
Stu,
I think Mark is saying that the front sealing glass plate in front of the CCD cover plate was not replaced.
The NR are generated from the CCD cover plate not the protective front cover plate.
Thanks, Ken. So there are two plates: one covering the chip (CCD cover plate) and a second one covering the CCD cover plate ( the front sealing glass plate). This second one is the one that dust motes generally sit on, correct?

Stu.
Lunt LS60THa B1200 PTFT
150mm H-alpha Solar telescope with Lunt35 mod
DMK41, Basler acA1920-155
NEQ6 Pro-mount
Fluxgate Magnetometers (1s and 150s Cadence)
More images at http://www.flickr.com/photos/solarcarbon60/

User avatar
Merlin66
Librarian
Librarian
Posts: 3369
Joined: Tue Dec 13, 2011 1:23 pm
Location: St Leonards, Australia
Contact:

Re: "Ghosts in the Machine"

Post by Merlin66 » Tue Nov 26, 2019 10:04 pm

Stu,
Generally the front window is "sealed" to the camera body to prevent any dust etc. getting inside to the CCD sensor. This being the case, 99% of the dust/ motes should be on the front of the glass window and easily removed.
Unfortunately, small particles (from the rear of the innards of the camera??) can appear on the inner surface of the window and on the surface of the sensor cover.
My problem was small motes on the surface of the CCD sensor cover.
"Astronomical Spectroscopy - The Final Frontier" - to boldly go where few amateurs have gone before
https://groups.yahoo.com/neo/groups/ast ... scopy/info
"Astronomical Spectroscopy for Amateurs" and
"Imaging Sunlight - using a digital spectroheliograph" - Springer

Post Reply