North America nebula

[Bloom]

This was taken around August. I used a very fast focal ratio, f/2,8, so I gathered abudant signal easily (the stars suffered a little - next time I will try it at f/5,6, but it will take several hours). The camera is not modified.

20x4min, Canon 200mm f/2,8, NEQ6,Canon EOS 40d (unmodded). Guiding: Starlight Xpress Lodestar with GSO 6" newtonian, and PHD. Image processing was done with Imagesplus, IRIS, and Paint Shop Pro X2). Image has been resized to 85% of the original.

[michael.h.f.wilkinson]

Very nice. those 200mm F/2.8 lenses are really great

[fredster]

Stunning image. Those Canon L spec lenses are truly top notch optically.

[Gina]

Very good

[Ags]

How long were the subs? That's a lot of HA for an unmodded camera!

[Psychobilly]

Nice...

A front aperture mask will avoid diffraction effects from the iris blades...

I had a set laser cut to replace the glass in a filter holder...

You don't need to go below f4...

After a couple of nights playing about , I still use my 200/2.8L at f2.8 with a slight tweak to the focusing method... I am happy with the results and prefer to get more signal...

Peter...

[Bloom]

Agnes, These were 4 minute subs at f/2,8. This is a really fast focal ratio (I try to follow the old rule "for nebulas fast focal ratios, for stars big apertures"). So, the camera gathers a lot of signal easily. After all, the N. Am. nebula is not that faint. With other emmision nebulae, and slower focal ratios (f/5) the camera has not been this successful.

Peter, a front aperture mask would eliminate those awful diffraction spikes indeed! I hadn't thought of it, thanks!

[Ags]

4 minutes at F2.8! I guess I'd better shoot this with my 50mm F1.8 at F1.8...

[michael.h.f.wilkinson]

Or try and get a Leica Noctilux 50mm F/1.0