Quote:
Originally Posted by TrevorW
HI Bert
Nice image
Any reason you went varying exposures on this I find with such even illumination across the FOV that this is not necessary myself
Cheers
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Bert shoots almost everything in HDR Trevor, With the limited dynamic range of a DSLR, and the unbelievable dynamic range out there in space, HDR is the way to shoot the night sky... A DSLR will saturate a bright star in 1 minute, where as the DSLR will not capture faint dust, nebulae dim stars, in 1 minute. Its a trade off normally, you either preserve stellar profiles and colours, or you get ample exposure for the nebulae and or dust in a FOV, and blow out the stars...
With HDR using a variety of different exposure durations, you are able to capture a very wide dynamic range from the very dim areas right the way through to mag -1 stars without suffering either under or over exposure...
A good example would be to shoot something like Sirius or Rigel, whilst also trying to capture all the background stars around it. you could do it with a 2 minute exposure, but the bright star would be bloated, and colourless. where as in a 15 second exposure the bright stars colour would be well defined, but the background stars would not be present...
having many different exposure durations allows a very gradual blending between the different exposures, making it seamless...
Worth experimenting, especially with a DSLR, but also with CCD's - despite their dynamic range advantage, the CCD cameras still do not capture the full dynamic range of every scene..
