Imaging with DSLR

[Stryda]

Hi, I'm hoping to do some DS imaging tonight of M51, I have a Canon 5d Mk2, and am wondering what settings I'm best using for the best final image. I intend on taking lights, darks, flats and bias, but my only issue is that Deep sky stacker has issues with the large file size of this camera, and often takes hours of stacking to finally crash , would I be best using the small RAW file size that canon has available? Or would that be a waste of the cameras performance? Any help from anyone using a DSLR for imaging would be greatly appreciated.

[laser_jock99]

Can you set a smaller image size? It's something I frequently do when shooting time lapse stuff.

[RikM]

Are you using lenses or prime focus on a telescope? M51 is pretty small so unless you are really getting up close and personal you don't need that large chip. I use a 1000D at prime focus on a 150P Newtonian and have thrown fairly large stacks of subs at DSS and it's not fallen over on me yet. e.g. 100x lights, 50x flats, 30x darks, 90x bias is not unusual.

Do make sure you haven't ticked 'drizzle' in the DSS settings because that can cause issues with DSLR stacks if you are using the whole image. If you have selected a small custom rectangle to stack, then drizzle should be fine.

[Stryda]

Thanks for the replies, I am using prime focus with it. To be honest, it's the only thing I have for imaging short of buying a dedicated CCD, but as I use the camera for daytime imaging quite a bit I decided to go down this route. I'll have a check on the drizzle setting, but I'm pretty sure I turned this off when I first started using DSS.

[jgs001]

A lot will depend on what you're connecting it to... somewhere in the order of 5 to 10 minute exposures is probably best. You want the largest RAW you can get. I too, like Rik, have stacked very large numbers of subs, 140 lights etc... not an issue, apart from the stack taking nearly 8 hours to run (an old computer). Drizzle will almost certainly be the problem, as 2x drizzle uses 4x as much memory etc.

[sgazer]

not sure if DSS has a specific issue with stacking 21MP images, but should be easy enough to find out by either resizing your RAWs or taking smaller RAWs with the S-RAW setting.

The advantage of high MP over low MP (apart from larger prints) is that you can crop the image that you see on the monitor more, but still have enough resolution to show the detail. When I view a 12MP image on a monitor, it's usually zoomed out to about 16%. A whole 21MP image will be about 10% to fit on the monitor. Zoom in to 100% and you'll see how much you could actually crop the image down to, before you run out of resolution.

So in summary, reducing the MP of the image your camera takes, will be throwing away information in those pixels, hence you won't be able to crop as much or print as large. For a good sized object, this is fine, but for tiny objects, where you want to crop a lot, it places a greater limit on what can be achieved.

[Stryda]

Ah, think I understand . Thanks for the advice, going out for a session in a bit, so will take some pics and have another go at stacking with DSS tonight