Couple of beginner questions:
Is M101 really the same (apparent) size as the full moon? If so, I assume the reason I can't see it is because it is so dim. Was this photographed using a piggy-backed camera or through a telescope?
I have a neximage digital camera (attached to the eyepiece holder) but all I can see is a small field of view (e.g. I can't image the whole moon, only a quarter at a time). So, if I was to take a picture like the above pinwheel galaxy, would I be better off using the neximage attached to my scope or just a separate camera piggy-backed on the scope?
Thanks,
Brian
Hi Brian,
Good questions.
1) It has an apparent size of 26 arc minutes. The Moon is about 30 arc minutes across. So it is approx 0.86 times the apparent size of the Moon.
2) Yes, it is dim because all the light is spread across a large area. Magnitude is based on condensing the light of an object into a pinpoint.
3) This image was taken with a SBIG ST-8XME CCD Camera attached directly into a 5.5" refractor. Focal length of the refractor is 980mm.
4) The area of sky which a camera can see depends on two things:
(a) physical size of chip
(b) local length of lens in front of it
The bigger the chip, the larger the area of sky that can be captured.
The shorter the focal length, the larger the area of sky the camera can capture.
With all these things, it's getting the balance right for the type of objects you want to image.
Also, different cameras work differently. Some are designed for fast exposure times for capturing detail on the Moon and Planets, whilst others are designed to take very long exposures and capture detail in deep sky objects.
Hope this helps,
  