1st DSO advice

[ScubaMike]

I will (next time we get sufficiently clear skies) be attempting to capture a "DSO" for the first time. I will be using a C9.25 with an F6.3 reducer, or a skywatcher ST150.

I would like a couple of pointers if you would be so kind.

1. Suggested target? I have always thought the Orion Nebula a stunning sight, would this be suitable?

2. Focus, how do I achieve focus on a (faint) DSO? get focus on a nearby star and then use goto to position on the object to image?

3. Capture, I will be using either a Meade DSI II or a long exposure modded SPC900. Which would be the better for a first time?

4. Processing. I don't have Photoshop, are there any suitable free tools I can use until I can afford PS?

5. What else should I do? I think I understand darks & flats how many of each though?

6. Which telescope of the above would be the better?

7. Filters. I have colour filters, a Baader Neo, and a SW LP filter, but nothing exotic. What should I use?

Sorry for being so dim, but we all have to start somewhere.

[Beardy Bob]

1. Yeah, that's nice and bright, but with a SPC900 or Meade DSI you'll only get a bit of it in the frame at a time.

2. Yes, use a bright star first (could take a while).

3. Dunno.

4. GIMP is good. Many of the same functions as Photoshop and completely free.

5. I usually take as many darks as I have time for at the end of the night. As long as I get one for every five lights it seems fine. Flats are tougher to do, but the exposure times are really short once you've got it all set up so I tend to go for eight to ten for each session.

6. Not an expert, sorry.

7. Go for none to begin with and see what you get. If the pics are all washed out with light pollution before you've exposed long enough to get any detail then use the filter, but results will be better without any filters if you can.

Go for it!

[ollypenrice]

The ST will give such awful false colour that I wouldn't try that. The FOV with the small chip on the long FL SCT will be very small. I think you can model it in the free Stellarium software. You put in your chip dimensions and focal length (with reducer) and it will throw up a box on the map of the sky showing the image you'll get. I do this in SkyMap Pro but it may be available in Stellarium.

The Trapezium region would be a good start. Or maybe a globular?

For focus you need a Bahtinov mask really, either bought or made, or a simpler Y mask.

Olly

[ScubaMike]

Thanks for the advice folks,

I'm still trying to get my head round why the CA in the ST is going to be an issue if I am using filters. I would have thought that restricting the colour being focussed would eliminate the CA (even if the focus required tweaking between each filter).

I have a bahtinov mask, so will try to use that more (I have been trying to get a visual focus, but as I have the equipment, it would seem logical to use it).