Red Noise on images problem

Hi, just up loaded two images i took over looking Lough Carra on Friday night just as Jupiter and the Moon were rising in the East. A beautiful and quiet place to do astronomy. My question is how do you remove this Red electronic noise which shows up on the left hand side of my images. I have used NEAT IMAGE and Paint Shop Pro, but am un familiar to there workings. I wish ther could be a workshop at Cosmos in relation to image processing techniques for wide field shots like these.

Ronan Newman



www.irishastronomy.org/user_resources/fi...ough%20Carra%202.jpg

www.irishastronomy.org/user_resources/fi...ng,lough%20Carra.jpg

That's amp glow from the ccd chip. Try doing a dark frame with same temperature conditions and same iso and exposure and use Registax or other to subtract from image. A stacked smoothed dark frame is best.

Hi Ronan, Mark is right, dark frames are best at doing this, take a few shots with the lens cap on for exactly the same time/fnumber/iso etc.

Mark, i'm only getting to grips with this myself, I have downloaded registax 3 for free, it's a great program, do you know exactly the sequence of steps you have to take to do dark subtraction? Is it easy?

Keith..

The best thing to do is to read the Registax tutorial

registax.astronomy.net/html/download.html

It is downloadable in a pdf file called "Controls and Functions".

Hello Ronan,

Agreed about the dark frames. You don't mention which camera was used for the shots (very nice by the way!) If the camera allows, you might try shooting in RAW mode or your camera's equivalent. These digital cameras are designed mostly for daylight shots, and when images are saved in .JPG the camera will apply a stretching algorithm and perhaps also sharpening and saturation 'enhancements.' All of these serve to emphasize noise and amp glow. If you can, take your shots and darks (and flat frames as well if used) in RAW, and do any calibration such as dark subtraction prior to stretching (brightening) or other enhancement. That way you're boosting the signal only, not the noise.

Cheers,

-- Denis Slattery

I think Ronan is using a Fuji Finepix - their version of a 300D.
They are nice shots Ronan! I love the eerie glow the moon produces! Its almost like a daytime shot with a heavy filter to block out the sun on the camera lens!

Am I correct is assuming that chip noise is down to the camera in question? For instance Ronan, if this same shot was done with the same settings etc on a 300D, then you probably wouldn't have as much noise. As Canon seems to have the upper hand in chip design, its something this camera category is stuck with!

Seanie.