Dobsonian Astrophotography

[RohunA]

_{I've been scouring the skies for the past two years, so I have naturally been drawn to the art of astro-imaging. The problem is that I have a dobsonian, 8 inches, and it doesn't track. What objects can I effectively photograph? I have a basic point and shoot camera, and 4 basic color filters. Are there any easy astronomy webcams that I can use to help me image the moon, sun and planets? Maybe some normal webcams that I can modify for astronomy purposes? My budget I'm looking at is around $100. Also quick side question. Will a 2 inch eyepiece dramatically improve views of galaxies? Thanks!}

_{Clear Skies,}

_Rohun

[ronin]

The reality is you are limited, the moon is bright and that means a simple 1/100 sec exposure should do, iso 400 or 200.

Planets I think still need some form of tracking, you end up using the scope and a barlow so a long focal length and things drift out fast.

DSO's are not a realistic option - have seen some excellent DSO images seemingly by a manual dobsonian but personally never sure, the old saying "If it looks too good to be true it probably is" always come to mind.

Depending on how dark it is you could use the camera if it can be set fully manual to get say 20 second wide field images.

20 sec, iso 800, full aperture and manually focused on infinity.

Webcam's it may be easier at least at first to get an inexpensive one, dismantle, remove the lens, reassemble - with the filter back in - and then use that. You get a movie of the planet and stack the best 20-30% of the frames in somethiong like Registax.

[ollypenrice]

Use a webcam or maybe the video facility of a DSLR for solar system objects. The rest will be very hard and limited to one or two ultra bright objects like M42 and M31. I'm afraid you won't get much. The webcam/video still approach allows you to track retrospecitvively by aligning each still to another one after the capture. Impossible with long exposures which will be trailed within themselves.

The only advantage of a 2 inch EP over a 1.25 is that allows the optical engineer to offer you a wider field of view. Most galaxies are small. OK, M31 is huge and needs a wide FOV but most are small and will fit in a 1.25. If a galaxy will fit in your FOV with a 1.25 there will be no advantage in a 2 inch. The widest FOV available in 1.25 would be provided by something like a 32mm Plossl.

Olly