First go at tricolor astrophotography

[Whitters]

Out with the Aero lens and the Starlight again. Image of M42 of course, taken thru red, green, blue and IR block filters then recombined using API4WIN and the Gimp.


[ This Message was edited by: Whitters on 2003-02-05 22:58 ]

[Ian]

interesting.

I'm afraid I'm not sure what to make of it. I can see M42 nice and clear and the colour rendition looks pretty and it's good and sharp. Last time I looked the sky was black (well orange). Is there a particular reason for the inverting the background while leaving the other details as they are? (really concerned about showing my ignorance here )

by the way did you use the IR block together with the colour filters? Which make/type are they?

[Whitters]

The blue background showing thru is because I could not be bothered to crop the image. Because it is made up of some 65 images, (20  Blue, 15 Green, 10 Red and 20 Luminance, all 5 seconds each. Taken from a fixed, undriven, tripod so I had to move the tripod after each colour and when lining up the frames there are patches where only one color recorded a value, in this case mostly blue.
Yes the IR-Block should realy be used with the color filters  but I didn't use the IR Blocker because I cannot get both color and IR Block filters in the holder, bit of a design flaw there...
I must send a note to the chap I got it from to see if he has any suggestions.
The filters are Astronomik type II from Gerd Neumann.

[Ian]

he he. If my last post made no sense, here's the reason...

Nutscrape in Linux chose to render the png with white as the 1st (or last?) colour of the palette instead of black. Hence the question about the inversion.

Now I've had a chance to look at it properly (Windows 2000/IE, yuck but there you go) it looks a lot more impressive. Sorry Paul, really good pic there. That was a lot of work that paid off.

Hope it hasn't made your cold any worse

sorry mate

[Whitters]

No worries mate , as for the cold I ran the wires into the house so all I had to do outside was to pop out and move the camera every now and again loking rather like the Mitchelin man.

[Rick]

Nutscrape on Solaris and on W2K are both flipping the base colour. I'll have to check what happens with Mozilla and xv at home this evening...

[Whitters]

Chaps try this image does it still have a duff background?

[Ian]

that is much better. It displays properly on my version of Netscape. What did you do to fix it?

edit: just read your pm. looks like that fixed it.

[ This Message was edited by: Ian on 2003-02-09 12:17 ]

[Whitters]

When saving as a PNG Gimp asks if you want to preserve the background, the first image I did preserve the background whe the second image didn't have the background preserved.

[Ian]

now I've really looked at that pic, you can really see the size of the nebula. It is easy to not appreciate scale when looking through the scope or looking at small field photos.

Do you think you could integrate for longer, perhaps using a scotch mount? or that old SP mount you have?

[Whitters]

If I could get a cheap option for a fix to the Super Polaris mount then that's what I want to do. The camera drive I have is too weedy to hold the camera and the aero lens.
The other option is to take more 5sec exposures