Keeping the dust out


Eric Weiner
 

Happy New Year everyone,

I'm looking for any advice from imagers on ideas to keep the dust out of my CFW.  I live on the Front Range in Colorado.  We have a lot of dust and wind.  Regardless how well I clean my filters and cmos cover, there is always a need for flats following imaging runs (perhaps this is common?).

My imaging train is all threaded except for the six machine screws which attach the spacers to the CFW.  The camera is attached to the CFW with six additional machine screws internal to the CFW.  The CFW is an QHY CFW-3L with 2" threaded Chroma filters.  The camera is a QHY268M.  I even tried applying electricians tape along the edge created by the two halves of the CFW, as well as around the CFW spacers.  I'm not really certain how the dust is getting in.  We're not talking significant amount of dust, but just enough motes to be noticeable.  We're also very dry here, so static tends to make them stick to these surfaces.

Any and all ideas are welcome.

Thanks,
Eric


ROBERT WYNNE
 

You might try wrapping the entire scope assembly with something like Saran Wrap. We do this in a clean room to assure some very sensitive units are completely isolated from atmosphere and fine debris. Unwrapping can be a chore and you need to be careful about removal so that you unwrap inwards to capture all loose debris. This is also a fairly inexpensive process; a few cents of plastic each time you wrap up a job. -Best, Robert

On 01/06/2022 2:32 PM Eric Weiner <weinere@...> wrote:


Happy New Year everyone,

I'm looking for any advice from imagers on ideas to keep the dust out of my CFW.  I live on the Front Range in Colorado.  We have a lot of dust and wind.  Regardless how well I clean my filters and cmos cover, there is always a need for flats following imaging runs (perhaps this is common?).

My imaging train is all threaded except for the six machine screws which attach the spacers to the CFW.  The camera is attached to the CFW with six additional machine screws internal to the CFW.  The CFW is an QHY CFW-3L with 2" threaded Chroma filters.  The camera is a QHY268M.  I even tried applying electricians tape along the edge created by the two halves of the CFW, as well as around the CFW spacers.  I'm not really certain how the dust is getting in.  We're not talking significant amount of dust, but just enough motes to be noticeable.  We're also very dry here, so static tends to make them stick to these surfaces.

Any and all ideas are welcome.

Thanks,
Eric


Dwight Fujita
 

I'm a fellow clean room dweller.

You might consider completely dismantling the CFW in a clean location and blowing out the inside surfaces.  Even if you get your filters spotless, particulate from the inside surfaces can transfer to your filters over time.  Avoid dismantling your optical train in dusty environments as much as possible.

If your CFW is old, maybe the belt drive mechanism is disintegrating and creating a particle source.  At work, we use EDX to identify sources of particle contamination, but I'm guessing you don't have access to an electron microscope...

-Dwight


ROBERT WYNNE
 

Depending on whether the belt is a polymer or metallic would drive the choice between testing using EDX or IR? -Best, Robert

On 01/06/2022 5:47 PM Dwight Fujita <kojifujitafodder@...> wrote:


I'm a fellow clean room dweller.

You might consider completely dismantling the CFW in a clean location and blowing out the inside surfaces.  Even if you get your filters spotless, particulate from the inside surfaces can transfer to your filters over time.  Avoid dismantling your optical train in dusty environments as much as possible.

If your CFW is old, maybe the belt drive mechanism is disintegrating and creating a particle source.  At work, we use EDX to identify sources of particle contamination, but I'm guessing you don't have access to an electron microscope...

-Dwight


Dwight Fujita
 

I think we just spent Eric's entire hobby budget.

Probably more useful advice for Eric, I've used a 10x loupe to get a closer look at surface contamination.  You can tell the difference between oil smears, sand (i.e. rocks), metallic shavings...

The 10x triplet loupe from this manufacturer is really great (don't bother with the other magnifications).  Pretty useful tool for $40.
https://www.amazon.com/BelOMO-Triplet-Folding-Magnifier-Anti-Reflection/dp/B00EXPWU8S/


Eric Weiner
 

Ha. I have a clean room at work where I do my cleaning. I also have a lighted loupe. It’s just fine particle dust intrusion. The CFW is only a couple years old. I have taken the time, without the use of scanning tunneling microscopes, to ensure all surfaces are as clean as possible prior to reassembly. It’s simply Colorado dust. I haven’t done a thorough cleaning followed immediately by the electrical tape sealing technique yet. It might work. 

Do others not have issues with dust?? 

Eric 

On Jan 6, 2022, at 19:38, Dwight Fujita <kojifujitafodder@...> wrote:

I think we just spent Eric's entire hobby budget.

Probably more useful advice for Eric, I've used a 10x loupe to get a closer look at surface contamination.  You can tell the difference between oil smears, sand (i.e. rocks), metallic shavings...

The 10x triplet loupe from this manufacturer is really great (don't bother with the other magnifications).  Pretty useful tool for $40.
https://www.amazon.com/BelOMO-Triplet-Folding-Magnifier-Anti-Reflection/dp/B00EXPWU8S/


ROBERT WYNNE
 

The dust I get in New Mexico is a far cry from the dust I get in coastal California. I would say NM dust is of a sort comprised of broken down chert or granite. The normal dust I get in California is of a softer type unless you're talking about beach sand (broken down silica). The normal CA dust is far less traumatic to clean than beach sand which will scratch the coating off a lens with the slightest motion/pressure.

Here I have a question. If one was willing to completely dismantle the lens assembly once a year and clean in an ultrasonic cleaner would that be an appropriate method or a big no no.

Best,
Robert

On 01/06/2022 6:52 PM Eric Weiner <weinere@...> wrote:


Ha. I have a clean room at work where I do my cleaning. I also have a lighted loupe. It’s just fine particle dust intrusion. The CFW is only a couple years old. I have taken the time, without the use of scanning tunneling microscopes, to ensure all surfaces are as clean as possible prior to reassembly. It’s simply Colorado dust. I haven’t done a thorough cleaning followed immediately by the electrical tape sealing technique yet. It might work. 

Do others not have issues with dust?? 

Eric 

On Jan 6, 2022, at 19:38, Dwight Fujita <kojifujitafodder@...> wrote:

I think we just spent Eric's entire hobby budget.

Probably more useful advice for Eric, I've used a 10x loupe to get a closer look at surface contamination.  You can tell the difference between oil smears, sand (i.e. rocks), metallic shavings...

The 10x triplet loupe from this manufacturer is really great (don't bother with the other magnifications).  Pretty useful tool for $40.
https://www.amazon.com/BelOMO-Triplet-Folding-Magnifier-Anti-Reflection/dp/B00EXPWU8S/


Joseph Beyer
 


I grew up and lived on the Colorado front range for about 30 years. Yes, it’s dust intrusion. For people who have not lived in that dry and extremely windy environment it’s hard to imagine the air pressure driving the dust…everywhere.  The static electricity teams up to make sure it sticks to everything.  The winter equivalent is spindrift that fills your tent overnight even when everything is zipped and sealed as tightly as possible.  

I live on the San Francisco peninsula now.  Dust in the yard is now only a problem generally in mid to late summer when things get bone dry.  The running dogs help spread the problem.  I’ve learned to only open the camera/filter compartments on still humid days.  If there’s going to be wind in the forecast I pull the OTA in and store it in closed room under a low dust cover. 

Eric, given the current weather conditions in Colorado now you’re definitely in the worst of it.  Really bad from what I understand.  You may try cleaning everything well in a room prehumidified for a half hour or so - like a bathroom if you’ve got room to work. That should knock down some of the dust and static charge.  I wouldn’t be worried about any parts getting steamed or moist, ordinary room humidity (or lack of) will remove it. After you get things clean keep the assembled telescope wrapped during windy weather with an anti-static clean cover.  I think the that’s the best you can do.  When the wind is blowing 90 mph and there’s no moisture the dust is going to be everywhere!

On Jan 6, 2022, at 6:52 PM, Eric Weiner <weinere@...> wrote:

Ha. I have a clean room at work where I do my cleaning. I also have a lighted loupe. It’s just fine particle dust intrusion. The CFW is only a couple years old. I have taken the time, without the use of scanning tunneling microscopes, to ensure all surfaces are as clean as possible prior to reassembly. It’s simply Colorado dust. I haven’t done a thorough cleaning followed immediately by the electrical tape sealing technique yet. It might work. 

Do others not have issues with dust?? 

Eric 

On Jan 6, 2022, at 19:38, Dwight Fujita <kojifujitafodder@...> wrote:

I think we just spent Eric's entire hobby budget.

Probably more useful advice for Eric, I've used a 10x loupe to get a closer look at surface contamination.  You can tell the difference between oil smears, sand (i.e. rocks), metallic shavings...

The 10x triplet loupe from this manufacturer is really great (don't bother with the other magnifications).  Pretty useful tool for $40.
https://www.amazon.com/BelOMO-Triplet-Folding-Magnifier-Anti-Reflection/dp/B00EXPWU8S/


Dwight Fujita
 

I image only from my backyard, so I can afford to heft my entire optical train outside without exposing it to the outside air.  I had a ZWO 1600mm that had some dust on the surface of the sensor (behind the outer glass protector).  Pretty easy to identify from the tiny size of the particles, and easy to clean off.  My flats are relatively clean, and the occasional dust speck tends to stay in place (easy to calibrate out).  It's dry and windy where I live, but probably not as bad as Eric.

I store my stuff horizontally to prevent dust from collecting on the sensor and filter surfaces.

Robert, it's not a good idea to submerge clean a lens unless you were able to dismantle it to its individual elements.  Disassembling, reassembling and collimating a lens cell is also difficult without the right equipment and experience.  If you're trying to get really nasty grit off the surface of your lens, they do sell some (expensive) polymer solution you can paint on the surface of your optics and peel off.  I haven't used it myself.  I do know you need to be careful that it doesn't seep into the edges of your lens cell .  They recommend using o-rings as dams to prevent the fluid from flowing behind your front lens element  (https://www.photoniccleaning.com/)

-Dwight


K. Maruf
 

Thanks kindly from another dust-bedraggled front range astro-nut. That loupe looks handy. 

To Eric, I have a similar QHY setup, and I too have to take flats regularly. Next time I think I will focus a bit more on the housing and construction of the sensor - though I can attest a previous QHY survived a 3 story drop with nothing more than minor cosmetic damage! 


M Hambrick
 

We are also coming up on pollen season here in southeast Texas. The pine pollen gets so bad in April that you can see it floating around at night through a flashlight beam. In just one night, it can leave your lens surfaces (and everything else) completely covered with fine yellow dust. I have gotten to the point that I don't even bother to set up my equipment during the peak pollen season.

Mike


Eric Weiner
 

Thanks all. From the experiences of the other folks who have lived here, it sounds like I'm doing all I can.  It's easy to verify with quick flats that the filters and cmos cover are spotless following dust removal/cleaning.  It isn't until the imaging train is put outside that my problem starts.  Again, its a problem, but nothing a set of flats can't take care of.  N.I.N.A's trained Flats and Dark Flats sequences make it easy.  An anti-static wrap while it's inside is a good idea, but the dust intrusion will still occur the first time I perform an imaging run.   

Yes, it has been a very dusty and windy winter here so far.  I've had to bring the OTA inside several times in the past few weeks due to severe winds (80-100 mph gusts).


ROBERT WYNNE
 

Believe me I understand the dangers of cleaning a lens element. It's a solution of last resort and not for the faint hearted. I've only cleaned a 10" mirror and a 6" lens (only only the front element). The 10" mirror ended up having to be recoated as some of the mirror had parted from the glass substrate even before cleaning. The A-P 6" cleaned up like a champ thanks to George. I live in the SF Bay area which BTW tonight is clear skies with little wind but chilly. I would suggest cleaning a lens element only as a last resort and certainly not as a routine practice. I still wonder why wrapping in Saran wrap wouldn't help keep most of the dust at bay? -Best, Robert

On 01/06/2022 7:43 PM Dwight Fujita <kojifujitafodder@...> wrote:


I image only from my backyard, so I can afford to heft my entire optical train outside without exposing it to the outside air.  I had a ZWO 1600mm that had some dust on the surface of the sensor (behind the outer glass protector).  Pretty easy to identify from the tiny size of the particles, and easy to clean off.  My flats are relatively clean, and the occasional dust speck tends to stay in place (easy to calibrate out).  It's dry and windy where I live, but probably not as bad as Eric.

I store my stuff horizontally to prevent dust from collecting on the sensor and filter surfaces.

Robert, it's not a good idea to submerge clean a lens unless you were able to dismantle it to its individual elements.  Disassembling, reassembling and collimating a lens cell is also difficult without the right equipment and experience.  If you're trying to get really nasty grit off the surface of your lens, they do sell some (expensive) polymer solution you can paint on the surface of your optics and peel off.  I haven't used it myself.  I do know you need to be careful that it doesn't seep into the edges of your lens cell .  They recommend using o-rings as dams to prevent the fluid from flowing behind your front lens element  (https://www.photoniccleaning.com/)

-Dwight


ROBERT WYNNE
 

I have to say 80-100 mph gusts coupled with sandy grit will sandblast most materials especially over time. -Best, Robert

On 01/07/2022 7:51 AM Eric Weiner <weinere@...> wrote:


Thanks all. From the experiences of the other folks who have lived here, it sounds like I'm doing all I can.  It's easy to verify with quick flats that the filters and cmos cover are spotless following dust removal/cleaning.  It isn't until the imaging train is put outside that my problem starts.  Again, its a problem, but nothing a set of flats can't take care of.  N.I.N.A's trained Flats and Dark Flats sequences make it easy.  An anti-static wrap while it's inside is a good idea, but the dust intrusion will still occur the first time I perform an imaging run.   

Yes, it has been a very dusty and windy winter here so far.  I've had to bring the OTA inside several times in the past few weeks due to severe winds (80-100 mph gusts).


Eric Weiner
 

For those interested, electrical tape around the CFW spacers and around the two halves of the CFW seems to be working.  At least under typical Front Range wind conditions.  I've got some gaffers tape on order to replace the electrical tape to avoid adhesive residue sticking to parts. 


ROBERT WYNNE
 

You might try some Teflon tape. No residue and pulled tight no leaks. Isn't that where we started? -Best, Robert

On 01/11/2022 7:37 AM Eric Weiner <weinere@...> wrote:


For those interested, electrical tape around the CFW spacers and around the two halves of the CFW seems to be working.  At least under typical Front Range wind conditions.  I've got some gaffers tape on order to replace the electrical tape to avoid adhesive residue sticking to parts. 


Eric Weiner
 

I haven't seen a Teflon tape suggesting in this thread actually.  Plastic wrap was suggested, but that would add static to an already static heavy environment.  Plus, it just isn't a very elegant solution, regardless of how effective it might be.  Honestly, I think our wind would make short work of plastic wrap once it got an edge loose.  Teflon tape between the CFW clam shells would likely work well, but the gaffer tape is easy, cheap, and adheres well to uneven surfaces.  I'm happy with the solution.  Thanks for all of the suggestions.