Dynamic Range Really isn't as important as you are lead to believe.

Started Jan 31, 2013 | Discussions thread
BillHinge
Senior MemberPosts: 1,029
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Re: Dynamic Range Really isn't as important as you are lead to believe.
In reply to mpgxsvcd, Feb 14, 2013

mpgxsvcd wrote:

Everyone talks about the newer cameras having more dynamic range. While that is true how often do you really use that much dynamic range?

Dynamic range only matters when the dynamic range of your scene exceeds what the camera can store and so it clips either the bright sections or the shadows or both.

If you have a camera with a lowly 8 stops of dynamic but your scene has less than 8 stops it won't matter at all. The camera will not clip any of it.

What most people think of when they refer to dynamic range is simulated dynamic range. Where the camera either artificially boosts the shadow exposure or where the camera combines multiple images of different exposures. Those methods can work well to get the image to look like you want it to but they don't really tell you anything about the sensors dynamic range.

If you really want to see dynamic range then photograph Orion's Nebula through a telescope or even better look at it through an eyepiece in a very large telescope. Your eye can see about 20 stops of DR and it will need a lot of that for the core of Orion's Nebula.

Here are two sample images. The first was made up of 6 stacked RAW images from the GH2 at ISO 1600. The second is a stack of 8 ISO 12,800 JPG images shot with the GH3 in HDR mode with +3 and -3 stops of extra Dynamic Range.

I think it is obvious that shooting HDR jpgs in this situation far outweighs shooting RAW. The few extra stops from shooting RAW is no match for the +6 stop HDR mode.



Here is a single GH3 HDR sub. Notice how the core is not blown out like it is in the GH2 RAW image? This is very difficult to do without an HDR mode.



All of these images are composed of approximately 1 minute subs and they were shot through the same 8 inch 800mm F4.0 telescope.

The GH3 is so much better than the GH2 for Astro Photography it isn't even funny. In fact the GH3 is much better than any Canon Rebel camera which has been the goto camera for AP for a number of years.

I had a try at this myself a few weeks ago using a GH2, the original subs weren't perfect but I still think the GH2 can do useful astro. First to admit the images below aren't perfect but they are stacked from a pile of rejects (only ones I have to hand at the moment till the weather improves)

This is 9 x 60s, and about 20 15s & 5s subs at iso800 - if I had more subs then it would be a bit smoother plus I did process it quite heavily to bring out detail. If you use the appropriate tools you can extract the DR from multiple RAW files (wavelet transforms). Notice you can resolve the trapezium stars

I aslo used an astronomik light pollution filter, this removed all the yellow, orange and light red below 540nm so the red channel is a bit deficient - all the red here is above 540nm

80mm APO triplet & GH2 on CG5 - comma on edges is due to incorrect field flattener positioning

These are cropped images, first by about 30%, second is crop that crop



This is a 100%+ crop so excuse the noise!



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