Astrophotography artefacts

[crayment]

I am new to astrophotography and wondered what the perfectly round dark shapes were on the images I am taking. I have attached a sample (stretched to emphasise the circles). The camera is an Atk 3i4L and the telescope a Skywatched ED80. Advice gratefully received. Many thanks in advance.

[GlassWalker]

I'd guess it was dust on or near the sensor. Clean it if possible, but you might get new dust anyway. Flats can help manage them.

[swag72]

Dust bunnies probably on your camera glass. Take it off the scope and give it a good clean, I use a microfibre cloth and Baader Wonder fluid. While you're at it, clean your filters too. Should be sparkly and new after that! They're not a problem though id you take flat frames, as these will subract them out during the calibration process.

[ollypenrice]

Most of us have nasties like that to deal with and, as stated above, the solution is to take flats. You really do need flats for any kind of serious imaging. It's just one of those facts of life on the dark side!

Olly

[ncjunk]

As already said its dust on one of your windows. I have baader cleaning fluid and a rocket blower (a hand pump for blowing air that looks like a rocket!).

The blower is the most usefull of the two with the cleaning fluid and cloth only used if the blower doesnt work.

With the cleaning fluid once you start with that you can end up spending ages with it trying to get rid of every single smudge...it becomes obsesive, hence i prefer the blower.

In the end though we normally just end up moving the dust to another bit of the image

[crayment]

That's great. Many thanks everyone for your advice.