Stacking without many stars

[Shibby]

Hi. I'm attempting to stack some images but, being mere 30s exposures, DSS can't find enough stars to align the images. It's a narrow view of the flame nebula region, where there doesn't seem to be many bright stars. I probably haven't got much but I just wanted to stack them to see if anything is visible at all. I've already tried the minimum detection threshold and even without median filter, but no joy. It's detecting around 7-13 stars for each image.

Any ideas? Can I align the images manually or with some other software?

[Helen]

Have you tried playing with the brightness setting before stacking? I seem to remember that working sometimes for me

Helen

[roundycat]

why can't you set it to align using two stars, one near each corner of the picture. Maxim aligns on two without a problem.

Dennis

[Shibby]

Maxim eh, I see there is a 30 day trial, I might have to try it. Helen there isn't a brightness setting in DSS is there?

[Helen]

There's a strip at the top right with black, white and grey triangles. Move the grey triangle to the left and you should see more stars. It might work!

Helen

[sgazer]

I think that strip might just brighten the image you see on the screen prior to stacking. However there is a threshold setting (settings>register settings), a lower value will pick up any stars if there are any, although too low and it will pick up noise. In the lower window pane, scroll across to the end and it will tell you how many stars have been detected.

[Shibby]

Hmm, yeah I've already tried the minimum possible threshold, I've also tried a higher threshold without the median filter but no joy. I can see the stars myself, so if I have no joy with Maxim, the only thing I can think of is manually touching up the stars before registering them in DSS. This would be time consuming though!

[sgazer]

hmm, I had a similar problem with some misshapen stars before. How about deleting 3 of the stars in PS and replacing them with 'perfect' stars. Not tried this, but it might allow aligment at least.

[dph1nm]

DSS will align with 8 stars - so if you have 7-13 most frames should be OK. Try the manual star editing option (display the image then click on the symbol on the right hand bottom side of the image) - sometimes DSS detects objects but doesn't think they are stars, even when they are! If so, you can use the manual editor to add them.

NigelM