Dust Motes on Flats [Deep Sky] Processing techniques · Jerry Gerber · ... · 5 · 221 · 4

In optical terms, you can’t have too many dust motes—at least up until more than about 40% of the total light is being blocked.  If you’ve got a good filter wheel, flats will correct whatever motes you have in your system and they shouldn’t affect the quality of your images.

Operationally, it’s good to minimize dust.  As you’ll discover, dirt gets EVERYWHERE in a remote installation so it is very important to seal everything as much as possible.  Even the tiniest opening will eventually fill with dust.   The related problem is that things at remote observatories are generally so dirty that it is very difficult to clean things in the field.  Just taking something apart and exposing it to the air for a minute or two is enough to gather dust—almost no mater how careful you are to blow things clean before putting it all back together.  The worst situation is when there’s a small opening that lets dust into your filter wheel (or camera) so that the dust motes change over time.  Whenever possible, I use a high quality 3M, wide temperature range vinyl tape to seal the interface between components and that has worked really well to keep dust out.  And I use a lot of it!  To a casual observer walking through the observatory, my scopes look like they are simply taped together.   The upshot is that my systems are completely dust tight and my flats last a REALLY long time—like for years.

Good luck with it Jerry!

John

John Hayes:
In optical terms, you can’t have too many dust motes—at least up until more than about 40% of the total light is being blocked.  If you’ve got a good filter wheel, flats will correct whatever motes you have in your system and they shouldn’t affect the quality of your images.

Operationally, it’s good to minimize dust.  As you’ll discover, dirt gets EVERYWHERE in a remote installation so it is very important to seal everything as much as possible.  Even the tiniest opening will eventually fill with dust.   The related problem is that things at remote observatories are generally so dirty that it is very difficult to clean things in the field.  Just taking something apart and exposing it to the air for a minute or two is enough to gather dust—almost no mater how careful you are to blow things clean before putting it all back together.  The worst situation is when there’s a small opening that lets dust into your filter wheel (or camera) so that the dust motes change over time.  Whenever possible, I use a high quality 3M, wide temperature range vinyl tape to seal the interface between components and that has worked really well to keep dust out.  And I use a lot of it!  To a casual observer walking through the observatory, my scopes look like they are simply taped together.   The upshot is that my systems are completely dust tight and my flats last a REALLY long time—like for years.

Good luck with it Jerry!

John

@John Hayes - do you simply "tape up" the connections?? Also the threaded ones?
I would really like to see a picture of it. It does seem like a simple and easy way to solve such a problem.

John Hayes:
Here's a quick download of a couple of phone shots.  The tape is only required on non-dust tight interfaces.  It's hard to tell in the photos but there are multiple layers of tape to insure that everything is completely air tight.

John

thx, that does give a good impression of the solution 👍