DSS can't detect any stars

[EA2007]

Hey all,

took 9 shots of M13 last night, plenty of stars visible yet DSS cant seem to detect any so as a result only stacks 1 image....any way to make it do its job properly ?

[jgs001]

In the register option, under advanced, you can adjust the star sensitivity. Reduce the slider from 10% to detect more stars... try reducing it to 8%, click the detect number of stars and see how many you get. I think you need at least 12, but I don't recall sorry.

[Psychobilly]

If John's suggestion doesn't work can you post a single sub for us to have a look at please...

[EA2007]

ahh, that's where i might have been going wrong...i turned the slider up, so i need to turn it down ?? shall give it a go, cheers : )

[Psychobilly]

If you have been turning it up then John's solution should definitely work

[EA2007]

Lots of stars at 8%

it's working now, thanks guys (& girls), I shall post the image when its done. I use IrfanView for post processing, do you have any other software ideas that would be good ?

[jgs001]

I don't know the capabilities of Irfanview in terms of stretching the image, you might do better with the DSS adjustments, then Irfanview to finish. Or use GIMP as it's free. It only operates in 8bit mode at present, so isn't ideal, but has full curves etc implemented in it. So a combo of the DSS adjustments mixed with GIMP to finish off...

[EA2007]

here it is finished:

Uploaded with ImageShack.us

[jgs001]

That's worked nicely... I'd suggest posting it on Imaging Deep Sky.

[EA2007]

Thanks,

I think my scope needs collimating though, its a Celestron C8 Schmidt Cassegrain. When I focus stars in it there always seems to be a bobbly bit towards one side of the star.

Also it focuses okay with the live view on my camera but when the scope is pointed vertical then I think the weight of the camera means it slips a little from the tightening screw that hold it in the EP slot, the screws aren't that great, so I think the image is out slightly of focus, hence the stars not being that pin-point.

Never collimated a Schmidt before...I know with Newt's you get the collimation cap but that won't work with a Schmidt will it??

[jgs001]

I used a collicap for a basic collimation of a Skymax... that was a right pain... Not sure on an SCT though... Probably worth posting a thread on that one too ... there's bound to be someone on here who has done it.