.... dust bunnies...

[Emanuele]

So, I have an integration of the Red filter, with a few dust bunnies. I know I should take flats but I am saving up for a flat field box.
Is there any way to remove them in PI ? Can PI make dust bunnies miracles? 

E.

[Carlos Milovic]

Miracles, not magic

In this case, take flats, even if they are not perfect (in the sence of large scale gradients). If you eliminate those donusts/disks but a large scale gradient remain, it is easier to remove with DBE or ABE.

You may try the white T-shirt technique

[Emanuele]

Thanks for the reply Carlos!

Unfortunately can't do that with this image. I setup and take down every time, and I am already back from the Alps. That's why I was hoping for a miracle... ehm..magic!

[sreilly]

Depending on the telescope, if the focus is fairly consistent at varying temperatures you should be able to take flats. A lot of people make a big deal about the rotation of the camera but unless you have a great deal of dirt obstructing the optics, anything at that distance won't be visible on the image. It's the dust on the cover slip and filters that create these artifacts in the first place. I would at least set up and try before I write the images off.

Steve

[Carlos Milovic]

Yeah, just try it. As I said, if you can get rid just of the donuts, or make them smoother, DBE may do the trick. Its the sharp edges the root of the problem.
Another way is to try to create a super flat out of your images...

[Emanuele]

Thansk Guys

How do I create a super flat from my images?

[Carlos Milovic]

Combine them without aligning the frames. If you took several targets, put them all in the stack. The idea is to get the background only, without any object.

[Emanuele]

ohhh, that is very interesting Carlos... Thank you.

So I will just Average Combine the frames that have the dust bunnies without aligning. What pixel rejections should I use to get the background only?

[Carlos Milovic]

Something that rejects a lot the brightest values. Be very aggressive on that.

[Emanuele]

Thanks Carlos

[David Raphael]

So which of the integration algorithms would you use for something like this? 

[vicent_peris]

Hi Emanuele,

Did you make dithering between frames? It's larger than the donuts?

At CAHA we have problems with moving donuts. But I found a multiscale method to integrate images that worked *very* well. We're going to implement this in ImageIntegration.

Best regards,
V.

[Emanuele]

HI Vincent

yes I do use dithering while imaging. I guide with a MiniBorg50 (250mm FL) and use a dither of 3 pixels.
The dust donuts are way way bigger than that: I'd say 100 pixels or more. The dust is on the filters.

I have not found a synthetic method of removing the dust donuts with PI, though

[vicent_peris]

Hi,

If you upload the image set, I can give it a try.


V.

[Emanuele]

Will do Vincent
Thank you!

I will send you the link to your email.