Are bigger sensors better for Digiscoping?

[odfuscate]

As a bird watcher with a spotting scope, I'm enticed by the concept of digiscoping with a small compact, rather than lugging round a heavy DSLR with an equally heavy lens. My result to date have been modest, "record" shots are possible but quality is indifferent.
While searching for inspiration I turned up an interesting post from Gene Smith who compared a small sensor LX3 to an bigger(4/3rds) OLY EPL1 and came to the following conclusion:_

"The SAME bundle of light [from a telescope]that goes into
a small optical system goes into a large optical system, that is
providing the small system can accept all of the light cone. Thus the
smaller sensor is more brightly lite, and the camera so responds. A
couple series of tests have defined why there is a problem with larger
sensor cameras. http://ohiobirds.org/forum/viewtopic.php?pid=4002

Is Gene correct? I turn to the intellectual rigour and technical nouse of this forum for an answer.

[carregwen]

I think what he is saying is that the (fixed) amount of light that comes down your lens tube (in this case a bird scope) produces a different result depending on the size of the sensor. That can't be true. It is the case that the light is concentrated on a smaller area with a smaller sensor, but the camera will adjust for exposure as it normally does. Surely there would be no difference?

How are you attaching the camera? I have a bird scope, and have tried attaching a Canon 350D using a special adaptor I bought. Mixed results though, even with a good quality scope.

[rpcrowe]

I have a neighbor couple who are avid birdwatchers and are quite involved with digiscoping. They are always trying new combinations of scopes and cameras and are absolutely satisfied with their results. They end up with bird images which they could not get unless they bought and carried huge and expensive camera lenses.

However their needs seem to differ from a "bird photographer" who is seeking shots of birds which are of the quality to print for exhibition. My friends' desires seem to be merely to record the birds they have seen with an image size in which the birds can easily be recognized. In this, their digiscope equipment is quite suitable.

I certainly do not intend to belittle their efforts. They produce images which are totally sufficient for their needs. However, their needs and my desires are not quite the same.

[JonathanC]

It all comes down to the relationship between the sensor and the image size.
If we assume that we want the little birdy to be, lets say 30%, of the frame height, we see that a bigger sensor needs a bigger image.
The bigger image requirement leads directly to more focal length.
More focal length (for the same f/ number) leads directly to bigger equipment.
This is why people photograph planets with a webcam rather than a DSLR.

HTH