Atik 16iC + ED80 focus help needed

[Spikey]

I've been setting up the newly acquired Atik16iC on the ED80 and running a few tests before trying it to image anything with.

I've got a 50mm extension tube and the focusser racked all the way out and it's barely in focus - is this normal ?

I've no filters or anything attached to it, just a nopsepirce into a 1.25 adapter > 2" 50mm extension tube > focusser.

It's literally hitting the stops and still not quite there.

[Earl]

I think you need a 80mm extension iirc i used one when i had one of those cam I use on on my QHY6.

Edit. Of course it does depend on how far the tube on the existing focus is.

[steppenwolf]

This is quite normal - remember that you have (should have!) removed the diagonal for imaging purposes and normally, this adds quite a bit to the light path length.

[Spikey]

Thanks for the replies. Yes, the diagonal doesn't come out of the case very often.

I'll try mating it with the focal reducer and then onto the 50mm extension tube into the focuser tube and see how that helps.

[Earl]

Ah a reducer will change everything.

You will need 55mm +-1 normally to get a flat field on the ccd from the reducer.

[Spikey]

Where is the 55mm measured from and to?

[Deneb]

Oh Yes, I remember how I fixed this, on the stock ed80 ds i loosened the 2" tube barrel adaptor slightly, locked the 'O' ring adaptor behind it, the inserted the 50mm extension tube with the ccd camera.

If your using a reducer then you need to have that 55mm spacing from the end of the reducer excluding the threads to the ccd chip. (no need to use the 50mm extension tube).

Nadeem.

[Earl]

You need to check the CCD tech spec for the depth the CCD is inset into the body from the mounting then use spacers or a variable space to suit, and sometimes a little tweaking will be needed to get it in the "Sweet spot"

[Spikey]

Thanks, thats much clearer now.

I never thought of loosening off the adapter. I'll give it a whirl without the FR first.