Red stripes on my M42??

[Specman]

Hi,

Finally got out last Saturday after months!

Decided to set up the camera through my PC for the first time and take some timed frames of M42.

Well I got 37 frames, 1 minute exposure, with 20 sec between shots to cool down,through my Sky-Watcher Evostar-80ED DS-PRO f/7.5 APO, 0.85x focal reducer. The images looked great in preview, nice sharp stars and good colour.

I stacked and processed through Pixinsight following Harry Page's guide (complete newbie) and my Orion image and the running man is fantastic, however my background has a red grainy lines in it

Its not too bad, but destroying what could be a great image. Why have I got this graining? Any ideas?

I live in a fairly dark location, though we still have street lights and security lights.

I always shoot at the same site and looking at my other images I have never had this before.

When I look at the individual frames its not there. I wonder if its a stacking issue, maybe a bad frame or two.

Any advice appreciated

Clear skies!

[Psychobilly]

Have you used any "calibration" frames in the stacking process.. in particular Bias or Offset and Darks?

Peter..

[steppenwolf]

Assuming that this is using the 1000D, I have seen this effect before but it can be fairly easily resolved in PhotoShop by using Noel Carboni's 'Horizontal Banding' action. As Billy has said, bias and dark frames will help to alleviate this in the first place as the bands are artefacts from the sensor.

[swag72]

Are you using your DSLR? If so, there is an issue with banding in the Canon's. In PI there is a script in the 'script menu' area to deal with Canon banding. Run it through the script and see if that helps.

[Specman]

Are you using your DSLR? If so, there is an issue with banding in the Canon's. In PI there is a script in the 'script menu' area to deal with Canon banding. Run it through the script and see if that helps.

This sounds EXACTLY the problem, I will take a look in PI. Do you have any further details on where the process might be and the best way to run it? Thanks

[swag72]

Open PI, click on the script menu toolbar along the top --> Utilities --> CanonBandingReduction.

You'll need to play with the settings to get the best result for your particular image.

Hope that helps.

[Specman]

Assuming that this is using the 1000D, I have seen this effect before but it can be fairly easily resolved in PhotoShop by using Noel Carboni's 'Horizontal Banding' action. As Billy has said, bias and dark frames will help to alleviate this in the first place as the bands are artefacts from the sensor.

Still a complete newbie on the photo front. Not taken bias or darks, still learning. I was just chuffed to get good tracking and captured some images. I never had problems before with the banding so just marched on, but I guess darks are a must and something I must get my head around.

[Psychobilly]

The bias can be taken at any time .. they may also be describe as offset depending on which software you are usign to calibrate and stack the images...

They need to be taken at the shortest possible exposure and the same ISO as the lights with no light entering the camera...

Darks need to be temperature matched to the lights... In cold weather the 1000D can be pretty good...They are taken at the same exposure time and ISO as the lights again with no light entering the camera...

At some point you will probably want to think about taking flats and thats a whole new ball game...

Peter...

[Specman]

Hi Guys,

I've stacked and processed upto DBE tool in PI. Here is the link to the tiff in Dropbox.

http://dl.dropbox.com/u/24775570/integration_DBE2.tif

I've played around with curves in both PI and Photoshop 5 but frankly I'm lost and still trying to find my way around.

If somebody could take a look at the image and see if its worth messing with I would appreciate it. I tried the Canon tool in PI with some success.

Cheers

Mark

[Specman]

Open PI, click on the script menu toolbar along the top --> Utilities --> CanonBandingReduction.

You'll need to play with the settings to get the best result for your particular image.

Hope that helps.

Thanks a lot! Handy tool & good to know.