How DR400 and RAW Saved My Bacon Today

Started Dec 26, 2011 | Discussions thread
ForumParentFirstPreviousNextNext unread
Flat view
Trevor G
Veteran MemberPosts: 6,466Gear list
Like?
How DR400 and RAW Saved My Bacon Today
Dec 26, 2011

I went out to our local body of water, Lake Hume, to see if I could have some fun shooting something water-based; after all, this is the middle of summer in Oz.

I came across some young dare-devils jumping from a bridge, so I switched Best Frame Capture on (instead of Continuous Shooting, which stops after just a few RAW+ images) knowing that I could get at least 8 frames exposed in rapid succession.

I didn't realise that BFC won't expose correctly if you have +0.3EV set from the previous exposure - my first 2 captures were wildy over-exposed. I deleted one of them, but fortunately left the other sequence as I realised that, with RAW capture, I still should have perfectly usable shots, just needing some simple PP.

That is what happened. Seven really easy RAWs to process, with 2.4EV able to be extracted out of the over-exposed highlights. Here are some screenshots with histograms to help you see the advantages of RAW over JPEG when things go wrong.

As it happened, this over-exposed sequence was the only good one I got - am I glad I stopped deleting in time!

Here is the RAW SOOC (straight out of camera) - it doesn't look good:

Same image after reducing exposure by 1.2EV in Silkypix.

You can tell this is a RAW because the highlights just keep on "unclipping" from the right hand side of the histogram; a JPEG doesn't do that at all, as you will see shortly:

Keep reducing the exposure slider untill all the highlights have been revealed in the histogram , and there is no sign of compression any more.

That takes all of -2.4EV; that's a figure unheard of in a small sensor camera. Even my Nikon D700 full frame camera with a sensor 4 times larger than the X10's only manages about 1.8EV of unclipping from its over-exposed areas in RAW:

I also brought down the lowlights to black. Doing that increases contrast and gives the image more punch. That took -20 units on the Black level slider:

Now let's look at the JPEG side. The OOC JPEG looks quite bad, just like the RAW. Compare the two histograms (RAW vs JPEG):

Bring it down -1.2EV, like the RAW, but look what happens, a harsh, cut off and clipped right hand side:

We could keep reducing the exposure like we did for the RAW, but there is no point - it would just make the JPEG very low in contrast without revealing any more highlights.

Once a JPEG clips , it stays clipped. No one (at this stage) can unclip a JPEG or recover missing highlight information once it has been compressed into that very small space:

To get it looking better, I added contrast by bringing the Black level slider down 75 points. Compare that with just 25 on the RAW.

In spite of the very bad clipping, this JPEG does not look all that bad, until you look closely at:

1) The white cloud has now turned green on the edges (cyan is probably a better description - this cyan colour shift in a blue sky is very typical of what happens when a camera is clipping its highlights - try reducing exposure by -0.3EV or so to overcome it):

2) The shoulders on the young guy standing on the bridge are clipped white.

I notice stuff like that, and I could never submit a photo with clipped highlights like this:

Sometimes, like in this example, you can almost get away with a badly over-exposed JPEG.

However, there are other times, such as with a white wedding dress, where you simply could not fix up the clipped, misplaced colour without seriously affecting something else, like skin colour.

-- hide signature --

Cheers

Trevor G

Silkypix tutorials at: http://photo.computerwyse.com

Fujifilm X10 Nikon D700
If you believe there are incorrect tags, please send us this post using our feedback form.
ForumParentFirstPreviousNextNext unread
Flat view
Post (hide subjects)Posted by
ForumParentFirstPreviousNextNext unread
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark post MMy threads
Color scheme? Blue / Yellow