This past week I had a gentleman stop me at a wedding and say I just got this (Canon) 30D. Are you playing with its big brother? Well it is no secret we have been using Canon exclusively for about 2 years. We also use an arsenal of 5D’s (we are anxiously awaiting the new 5D II’s arrival in November). While Canon has made a few changes to the line up it is true that the 5D was just a step up from the 30D a short time ago.
So what are the difference in a camera like the 30D and the 5D. IMAGE QUALITY! And if image quality is of importance to you you may want to pay twice as much to get the 5D. To us the 5D is a perfect blend of performance, image quality and weight (yes after holding two for 10 hours straight you will know what I mean). First the 5D has a full frame sensor whereas the 30D has a cropped sensor. What does this mean in theory and actuality. First in theory the sweet spot of the lense is in the center. So in theory the smaller sensor of the 30D (physical size) should produce a sharper overall image. In actuality the sensors are not the same sensors and manufactured in different Canon plants. What we have noticed is the images are softer overall and at higher ISO’s the images are much more grainy (contain more digital noise). Next most 35mm camera systems were built around the 35mm format. So the 85mm lens (which was the beginning of the a decent portrait lens with the 30D’s smaller sensor ends up being a 136mm which is great but hopefully you have the room to back up to get the photo. If you try to compensate and purchase a smaller lens such as a 50mm you would have the same framing as an 80mm in camera. The problem is the distortion you will get with a 50mm lens acting as an 80mm (not flattering to the human form and especially the face).
The final thing is build quality and weather proofing. From what I have seen both the 30D and 5D have similar build quality (other than the goofy pop of flash on the 30D). Weather sealing is supposed to be a little better on the 5D but if you were to look at the two side by side you would not see any difference.
So outside of what I just mentioned about the 30D I do not know much especially if you ask me what a good point and shoot as I have no idea.