M83 Hypertune

allan gould · #1 19-01-2010, 12:17 PM

Just managed to grab 13x4 min shots of M83 before it disappeared behind my neighbour's roof. Taken with DSI II with 10"SCT on my newly hypertuned EQ6 mount after a final adjustment of the gears and worms etc.
Processed flats and darks etc with DSS and PS. Needs more data for a good pictur but since the aim was to check guiding I also did a 10 min shot guided with PhDguiding and was happy with the round stars.
Comments welcomed

duncan · #2 19-01-2010, 12:27 PM

Nice shot for such a small exposure AL. I'll get there one day,LoL.

Cheers, Duncan

rogerg (Roger) · #3 19-01-2010, 03:57 PM

I guess you could process much more information out of that image with the same data, than you have here. Of course I don't have your setup so can't say for sure, but normally I'd expect more data in 4 min shots.

I took this last year, comprising of 2 minute exposures:
http://content.rogergroom.com/cms/000896.jpg

sure... different camera, but I'd think your DSI would still give you something near this for 4 min vs my 2min exposures.

13 shots at 4 mins is reasonable to have a good crack at a target like this in my opinion.

allan gould · #4 19-01-2010, 06:04 PM

Normally I would agree but the DSI was running at 28oC while the ST7 would be close to 0oC if running 80% at that ambient temp. Thus the noise isnt comparable between the two cameras and from experience those of us that use DSI cameras usually aim for 50 shots to get a smoother background so that when curves are applied, the noise isnt as prominent.
Also the colours in your shot are 2x2 binned which the DSI cant do and that boosts the sensitivity quite a bit ie 4x for the 5x2min colour shots=an additional 40 min total of data which when added to your luminance gives 30min+40min=70 min total of 1x1 data. The total for the DSI was 13x4=52 min total.
But I agree I could process more information but I really wanted to see how good the guiding was at this stage after the hypertune.
Its all relative anyhow and different cameras have different QE so its hard to compare - but non-cooling of a DSI really messes with the image.
Thanks for your comments Roger and Duncan

peter_4059 (Peter) · #5 19-01-2010, 06:25 PM

I guess there is also the difference in aperature (12" vs 10") and location. Allan is only a few kms from the centre of Brisbane and based on Roger's website it looks like he in located in the Perth hills so a reasonable distance from the city (probably similar to imaging from Samford). The skyglow around here is pretty bad.

rogerg (Roger) · #6 19-01-2010, 06:36 PM

Yeap, fair enough. I didn't realise the DSI II wasn't cooled. Anyhow, irrespective of that it was just a feeling I had that there should be more there, and full well realise the setup's are quite different (most notably in QE). My colour is pretty ordinary to say the least and wouldn't have added to the overall brightness or detail at all. Quite interesting to compare. Thanks for sharing the pic

Congrats on the good guiding, something I currently lack

telecasterguru (Frank) · #7 19-01-2010, 06:38 PM

Allan,

I think the guiding looks spot on if you did the 4 minute subs without the guide scope.

There is no way I could get 30 seconds unguided out of my EQ6.

Frank

TheDecepticon · #8 19-01-2010, 06:57 PM

I think it is good for the time.

SkyViking (Rolf) · #9 19-01-2010, 08:19 PM

I think there is some good data in your image, as Roger said you can probably stretch it a bit more.
I took this shot with a ToUCam, 38 x 1min. I believe the performance of a ToUCam is similar to the DSI, more or less.
So your image can most likely handle some extra processing, there seems to be enough data in there