Family photography v's astrophotography??

[Merlin66]

Why is it we always seem to end up going back to the ol' days of family photography when discussing telescope/ camera set-ups for astrophotography?? APS-H, APS-C, micro four thirds 4/3" etc etc

The "total pixel count" and "frame size" of standard camera chips doesn't mean all that much to the AP......

The pixel size, QE. and chip size (in pixel/ mm) to allow analyse the plate scale and possible resolution are important. The telescope aperture and effective focal length then give us the light gathering/ resolution and plate scale of the image.

[gregbradley]

I agree to an extent but sensor size does come into for field of view primarily. Larger chips give a wider field of view on the same telescope than a smaller sensor does.

Pixel size needs to match the focal length and the seeing conditions for optimal sampling. Usual standard is 1 arc second per pixel for average seeing.
I have been able to do .43 arc sec per pixel under more ideal conditions and get sharp results. I have used slightly lower than that with a 5.4 micron pixelled camera and it gave fuzzier results than a 9 micron pixel camera.

Also I think a lot of this mainly applies to CCD and perhaps not as much to CMOS where the read noise can be a small fraction of the CCD sensors.

Eventually it seems CMOS will replace CCD as the money is going into CMOS and they are now outperforming their CCD brothers. Some are backside illuminated with advanced circuitry and very low read noise and large numbers of pixels.

The available CMOS sensors though are micro 4/3rds and rather small so you don't see too many very widefield type images from them yet.

Greg.

[Merlin66]

Yes.....
But I think we should push to use the physical dimension of the chip in astronomy and AP rather than the camera designations....

To me a 5.7micron pixel, 3906 x 2602 matrix, (22.2mm x 14.8mm) chip description is better than a 10 million pixel, APS-C description.....

[NorthernLight]

Seconded. It's like answering "a blue one" when asked what car one drives...