Stacking Images for Greater FOV

[Dboots (Duncan)]

Hi All,

I have a 14" goto dob and I tried to stack a number of images that I took on Saturday night to mosaic an entire image of M42. I tried the mosaic option in DSS because the FOV with a Canon 60d at prime focus is 48x32 arc minutes and M42 is approx. 85x60 arc minutes.

Anyway, after going through approx. 200 subs, adding darks etc, the result was crap...

Is there a trick to mosaicking images for greater FOV or is it just really hard to get right?

Thanks,

Duncan

[LightningNZ (Cam)]

Hard to say based off that! Can you post what you came away with?

I've always found that it's damned hard without mosaicking software controlling my (admittedly) equatorial mount I end up with very uneven overlap across my images.

So the way I do it:
Take a small stack of images on one area, then move on. Each stack of images gets the DSS treatment but I don't stretch the final images. I then mosaic the stacks with Microsoft ICE (great piece of free software). The final result I save and process in Photoshop.

If you just take single frames with movement in between then you're probably gonna be screwed cause it's hard to register the whole area. DSS can do it, but I keep running out of memory at full res.

[ralph1]

In the mosaic I'm currently working on the biggest problem is field rotation. I'm using a motorised altazimuth mount like your dob with a camera on a tripod up against the eyepeice and even after 5 minutes the field has rotated significantly. Maybe that's the problem.

[LightningNZ (Cam)]

Field rotation sucks, but MS ICE should still be able to deal with it. Great program.

[Dboots (Duncan)]

Hi All,

Thank you for your input. I thought I had deleted the image because I was so displeased with the result but I found the DSS autosave file. Attached is the image as I left it. I didn't finish the processing.

You can clearly see the lines where the stacked images intersect. There is also is evidence of image rotation in the diffraction spikes.

Thanks to your input, I can see that attempting to stack approx. 200 subs of the entire area was the wrong thing to do. What I might try next time is stack the subs for each set, create a TIFF for each set then mosaic the TIFF files. Hopefully that will improve the result.

Duncan

[rustigsmed (Russell)]

nice attempt, I would do a number of different stacks as suggested already and then use mosaic program to stitch together rather than have DSS attempt a stitch.

here is a mosaic I did with many fov's going from carina neb to Gabriela mistral (also on goto dob)https://www.flickr.com/photos/803366...ream/lightbox/

I ended up with a number of different images from dss then stitched in Microsoft photo gallery (probably already on your computer) - saved as tiff.

cheers