dust bunnies help plz

[iwols]

hi all after getting my ed80 out for the first time in about 3 months,it was like starting again,(doh) after having some building work done the scope was packed away out of the way,but after trying the scope out again i have a few dust bunnies,in my train i have the filter wheel /reducer and the camera and obviuosly the scope lens,where would you suspect these bunnies and can you check for bunnies during the day cheers

[bingevader]

I dunno about bunnies, the one just above centre looks more like a horses head!

Nice picture, I hope someone can help clear it up for you.

Merry Christmas.

[iwols]

1 minute ago, bingevader said:

I dunno about bunnies, the one just above centre looks more like a horses head!

Nice picture, I hope someone can help clear it up for you.

Merry Christmas.

like it 

[symmetal]

By the size of them they are probably on the front surface of the glass plate protecting the sensor of your ccd camera. If they don't move when you try different filters, or after you rotate the camera, that would confirm it. You can check during the day by effectively taking a flat and checking the image. Point the scope at a reasonably neutral surface, no need to focus and take an image which isn't saturated or too dark. The bunnies should show up. Whether it's worth trying to get them off is another matter. Normal stacking with flat frames will remove them.

Alan

[Davey-T]

Lurking somewhere on here is a formula for working out how far the dust is from the sensor.

You can take flats in the day to show your dust bunnies.

Dave

[iwols]

thanks guys

[iwols]

7 minutes ago, symmetal said:

By the size of them they are probably on the front surface of the glass plate protecting the sensor of your ccd camera. If they don't move when you try different filters, or after you rotate the camera, that would confirm it. You can check during the day by effectively taking a flat and checking the image. Point the scope at a reasonably neutral surface, no need to focus and take an image which isn't saturated or too dark. The bunnies should show up. Whether it's worth trying to get them off is another matter. Normal stacking with flat frames will remove them.

Alan

would a light screen do ,bought one ages ago but never used it

[Davey-T]

Should do you just need to experiment to get the right exposure length and take some flats.

Dave

[symmetal]

22 minutes ago, iwols said:

would a light screen do ,bought one ages ago but never used it

Yes it would be fine, but you don't need a perfectly uniform surface to look for the dust bunnies as you won't be using them as flats, just as a bunny check. 

Alan

[Pompey Monkey]

Personally, I wouldn't bother looking for the cause.

I'd just take a good set of flats and then the problem will be no more! ?

Top tip: The fewer times that you disassemble the imaging train, the less often that you need to take flats!

[DaveS]

They are unlikely to be further away than the filters. Do they change depending on which filter you're using?

Myself, I'd dismantle the imaging train up to the reducer, dust everything (Ideally with a carbon fibre brush), reassemble it then take flats. As Olly pointed out in my thread on dodgy flats, take them in the dark with a flat-field panel to avoid any light-leaks that there may be.

[iwols]

thanks guys sorted now it was on the ccd lens cover but it took 3 goes at cleaning

[iwols]

and just a final mix of the very little and poor data i had