Could someone have a wee look at my M51 unprocesses TIFF

[tooth_dr]

Hi guys

M51 data from Thursday 4th,

Imaging: 250px / Modified 300d

Guiding: EQ6 / ASTSC15BW / ED80

Exposures:

Lights 52 x 300s / ISO 800

Darks 29 x 300s / ISO 800

Flats 10 x (at whatever exposure it was that made histogram half way!) / ISO 800

I keep getting diagonal banding on all my 300d images, but now that I've an obs and trying to improve my images, I want to know if I'm intorducing them during processing, or do I need a new camera?

I would be most grateful if one of you could have a go at processing it? I've attached the TIFF file hosted by uploading (I hope this is a 'safe' site for this)

Download Autosave.tif for free on uploading.com

Many thanks

Adam

Here is what I've done so far:

[Psychobilly]

Hi Adam...

Any chance of the file straight out of stacking...

Peter...

[tooth_dr]

Hi Peter, I've attached a link to the tiff file straight out of DSS

Thanks

Adam

[Psychobilly]

55 MB from a 300D - I guess you are saving 32 bit tiffs

I wont download from there to many dodgy pop-ups sorry Adam...

Peter...

[tooth_dr]

LOL, if you say so. I just use standard DSS settings and I always got 32bit files. I thought this was the way of it! I always convert them straight to 16bit in CS2 anyway so maybe I could do something different?

[Psychobilly]

You can change it so that DSS will save 16 bit files which wil be a lot smaller...

[Starflyer]

It looks like read noise, I'd try it with a lot more flats and also take bias frames. I take around 75 to 100 of each with my 450D and throw them into DSS with the lights and darks.

A bias frame is taken at the shortest exposure possible, same ISO and in the dark (ideally zero but you can't do that with a DSLR). This will record the read noise from the camera, DSS then uses this information to 'remove' the read noise.

[tooth_dr]

I'll stick some Bias frames in then! Using 1/4000 then?

[Psychobilly]

yes 1/4000s same ISO as the lights make sure no lights leakign into the cam ...

[Starflyer]

Yep 1/4000 if that's the shortest exposure.

If you've not disturbed the camera and focuser you could also retake your flats. I'm not 100% sure, but I think using a low number of flats will also add noise to the image even though it removes the vignetting.

[tooth_dr]

I didn't know that about flats, but the camera is off the scope because I decided to have a quick nosey at Saturn at 4am when I was packing up d'oh

[Psychobilly]

When it comes to any of the "calibration frames" I look to get 30-40....

Peter...

[tooth_dr]

Righto - no reason not get that many I suppose! I used to use 5 (!) crickey. 30-40 it is then,

[Psychobilly]

Its the darks that take the time... I grab the Flats (EL panel makes this a doddle) , Dark Flats and Bias straight after closing up the obs and then just leave the camera doing darks... using whatever timing was used between light subs ...

Peter...