Close ups

[mikeglr]

Hi this might sound like a silly question but what is the art of close up's of dso's is it just a case of cropping in Photoshop or is it magnification ,also what scope would be best for this I've got 10" newt and 80 refractor

[arad85]

Depends on the size of the DSO

Image size is totally defined by the focal length of the 'scope and size of the chip.

Take a look at this post (and the one after it) I prepared earlier

http://stargazerslounge.com/imaging-discussion/96681-imaging.html#post1372048

[MikeD]

I image with the same setup :10" f4.8 newt and 80ED, the newt is my weapon of choice when it comes to getting up close and personal with a DSO.

It's the focal length that determines how close in you get on a DSO when imaging at prime focus. A scope of 1200mm focal length ( 10" newt) will be twice as close in as a 600mm Scope 80Ed.

I like to think of it like a projector projecting an image on to an A4 sheet of paper, the closer the projector is to the A4 sheet of paper ( shorter the focal length) the smaller and brighter the image is and the more of the image fits on the sheet of paper (bigger field of view), the further away the projector is to the sheet of paper the bigger and duller the image ( shorter focal length) but you also fit less of the image on the piece of paper( smaller Field of view).

The other thing to consider is the size of the objective,the 10" newt mirror is 254mm and the 80Ed lens is 80mm ,back to the projector analogy the bigger the objective number the brighter the bulb in the projector, so the brighter the image hitting the camera.

Have a look at my web site under " HX916 Deep space objects" in the gallery to see the image scale I get with my 10" newt and Starlight express HX916 CCD.

Hope that helps

[mikeglr]

Thanks that's most helpful

cheers mike