Old 05-08-2006, 07:13 PM
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Sensor Size Comparison

Hi All

I'm curious, to find out the answer to this:

If one uses a Canon 350D, or any other DSLR for that matter, and takes images, one has to combine many images of short exposures to get a satisfactory result.

However if one uses a Canon 5D, which is full frame, would one have to combine that same image, or would a single timed exposure be sufficient.

Also how would the Canon 5D stack up against the Canon 350D for imaging.
I know the price of either may have some influence, but is the 5D good for astro work, so to speak
Would be interested to hear from the more experienced.

Thanks Leon
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Old 05-08-2006, 08:23 PM
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Striker (Tony)
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Hi leon,

1 single exposure through the 5D is no different to a single shot through the 350D...however the 5D has much larger field of view.....it all depends on what you want to image and with what scope...their is no such thing as the perfect scope or camera as all benifit in different areas...for example...the 5D is terrific for Wide field imaging because of the size of the image sensor/chip...it has no benifit imaging a single galaxy.

Bert has produced some wonderful widefield image using the 5D combined with a modified 100ED scope...you can produce the same fov images by using the 350D with a shorter focal length scope.....it all depends on what you want to achieve....but answering your question between models NO it makes no difference on the amount of exposures needed to produce a nice image.
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Old 06-08-2006, 09:31 AM
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Just to elaborate on what Tony said, the major difference is field of view with the 5D.

As an example a 4" f5 scope would yield a field of view of about 2.5 degrees wide with the 350D. With the 5D it would be closer to 4 degrees. Furthermore the larger pixels in the 5D mean that it is more sensitive to extended objects like nebula.

Taking this further to get the same 2.5 degree field of view with the 5D you can now employ a larger 6" f5 scope. So for the imaging the same area of sky the 5D will have over 2x the sensitivity of the 350D. However you will need highly corrected optics to realise this gain.

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Old 06-08-2006, 12:15 PM
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astrogeek (Leon)

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One more thing is that generally the larger the CCD the less noise will be in your image. This is because in a larger CCD the individual pixels are further apart from each other and are therefore less likely to interfere with each other. Hope this helps ,

The other Leon
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Old 06-08-2006, 07:06 PM
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Thanks for the advice guys, i will take it all on board.

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Old 06-08-2006, 09:41 PM
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dugnsuz (Doug)
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$4.5K for a 5d body - scary stuff!!!!!!!!!!
Cheers in awe
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