DSS stacking question

[graham.hobart (Graham stevens)]

Hello as a newbie imager and without RTFM on DSS, I tried to stack some raw frames , the jpeg ones I took at the same time seemed reasonably close enough to get alignment stars. But when I registered them and tried to stack, it said only one frame was good enough for stacking. The settings were the normal. I tried adjusting the star setting from 15% to 71% and it still only wanted to stack one frame
Please advise
Graham

[jjjnettie (Jeanette)]

Hmmmm a few of us have had that trouble before.

Myself, I never bother to register the images first. I just load them all into DSS, click on Check All, then go straight to Stack Checked Pictures.

Maybe reinstalling the program will help.

[graham.hobart (Graham stevens)]

Thanks JJJ, I will give that a go.

[midnight (Darrin)]

Graham,

DSS needs at least 8 stars to successfully proceed and the critieria is that they need to be reasonably round (DSS manual)

How many frames are you trying to stack?
Are they RAW or JPG?

Try doing a "compute offsets" first to see the score DSS applies to each frame. This does not start any aligning etc, only used to analyse your data and any possible reasons for DSS not wanting to stack.

DSS also doesn't like too much field rotation. See my example below in the animated GIF. The gif is only 2 frames but the 1st is a score of 4712 (highest and therefore DSS uses this as the base and therefore a dX and dY = 0) The 2nd frame is almost the worst as indicated by a relatively lower score of 4238 but this frame has the highest field rotation showing it has deviated by +3 pixels in the X direction and -3.5 in the Y - ie my mount is not perfectly polar aligned and/or there is flex. These shots were unguided too btw.

Image 1 = Offsets. Note that I have ordered top to bottom by filename and hence the top is earlier in the night, bottom later in the night. Note too the dX is consistently increasing from - to + which is clear indicator the sky is rotating slowly wrt the mount due to inaccurate polar alignment.
Image 2 = animated gif. Pay attention to preview screen and note how the stars seem to jump slightly. On a mount perfectly polar aligned, there would be no jump in the gif animation.

This might help you diagnose why DSS is not stacking. There is almost always a logical reason why it won't. This is where I struggled in earlier days to get it to stack more than 2 or 3 out of 20 odd frames. In this example, I was able to stack all frames as DSS was happy with these tolerances.

I hope this helps you. Good luck and if in doubt, keep bugging us as I am sure many others may have a similar problem and we'd be happy to share our knowledge gained.

Cheers,
Darrin...

[graham.hobart (Graham stevens)]

They were canon raw files of omega centaurii so I hope they would have enough stars. I downloaded the latest version (1.3.3? ) and tried again without registering them.Same result.
I check boxed them and pressed compute offset and the box flashes up for a nanosecond then goes. I must be doing something wrong.
There were ten frames.
I wonder whether the rotation was too much as this was my first 'close' polar align'.
Does nebulosity stack RAW frames?
Graham

[midnight (Darrin)]

Graham,

What Canon camera are you using? I know a few people here have struggled with the Canon 550D and possibly newer and had to use ver 3.3.3 from memory.

The clue is in DSS not even doing a compute offset. Albeit the compute offset is fairly quick (about 1sec per light frame). By default, DSS does not check your lights. But you have indicated that you have checked all.

1. Is your camera a relatively newer model (eg 550D, 60D)
2. Have you checked all and even checked that a tick appears in the far left checkbox of each light frame
3. Compute offsets should take a few seconds and report back your dX and dY and rotation and quality (score).
4. If you can not get DSS to get past step 3, then there is no point going on as DSS is not attempting to process. There may be a possibility the RAW file is not being read by DSS
5. If in doubt, use Canon's Digital Photo Pro and batch export your raw files to a TIFF file.
6. After step 5, run DSS again but this time with your TIFF files that you exported in step 5. Repeat steps 2 & 3.
7. If DSS does come back with results of the compute offsets, then you are ready for the next step of stacking. The root cause almost certainly appears to be in the way your version of DSS is handling the RAW files from your camera.
8. Good luck

Cheers,
Darrin...

[jenchris (Jennifer)]

the recognise stars should be down at 2% to work if your frames are a bit iffy

[graham.hobart (Graham stevens)]

yes- have just read a good DSS tute on line so I now realise I should have RTFManual!
watch this space for processed meats!
Graz

[graham.hobart (Graham stevens)]

Thanks all, I tried my hand at DSS tonight and these are the results. I ma guessing I can get rid of the dust bunnies with flat frames?
I only did stacking & darks tonight but am pleased with results
Graz
M83 in electric blue!

[dannat (Daniel)]

nebulosity does stack canon raw files - but not from other camera brands