M81

Thanks guys

Deegee
I know what you mean about the centering of the image. A bit more patience at the time would have been well worth it. I used a 0.5 atic focal reducer on this image but I think even so the galaxy was too big for the field of view of the scope. Maybe if I get a 0.333 FR it would help reduce the f ratio down further and increase trhe FOV.

I understand your analagy with short exposures and long exposures and the risks and benifits. However I found with the shorter exposures I was getting 50-60 shots of basically just "core" and very very faint spiril arms that would desend into mush if I even thought of stretching the image. DSS wouldnt even stack them so I was left with nothing. Again this could be just down to imaging at f10

(I think DSS has become even better since so I could try it again though)


Non linear streching. Is this a tool you can get with Photoshop? There was plenty of detail in the core but in order to get the spiril arms I had to blow out the core.

Next time: cheer:

DeeBee,

Download FITS Liberator, a NASA product, which includes a number of nonlinear stretch routines. I really like the ARCSINH (as well as the double ARCSINH) routine which works beautifully with high dynamic range images.

For your info: www.spacetelescope.org/projects/fits_liberator/

AyAy. :laugh:

Dave Grennan wrote:

As DaveMc said, getting the longest you can get away with is good, but only if it is reproducable every time.

Excellent point.

DeeBee - keep at it and perservere - it'll pay off. You're on the right track.

Thanks Antony

Fits Liberator.I thought that needed photshop before you could use it.

DavidBranigan wrote:

Thanks Antony

Fits Liberator.I thought that needed photshop before you could use it.

Yes and no. It can be used (ie. accessed) via Photoshop if you wish by loading it as a plug-in. Of course, it can also be used standalone as well.

Anthony.