Friday, July 1, 2016

Dual-ISO continues to deliver!

As readers of my posts know, I am a single-minded Magic Lantern user. As the UK summer has decided to not show its face yet, or at least until Wimbledon is over :-), I found myself 'playing around' in Lightroom this afternoon, and decided to see what ML Dual-ISO can really do.

For those that don't know what Dual-ISO is, the simplest way of understanding Dual is to think of it as ISO bracketing but all within one image capture. Thus, rather than take one image at ISO100 and one at ISO800, say; in a Dual-ISO capture alternate Bayer line pairs are switched between ISO100 and ISO800.

As an example, let's look at this Dual-ISO capture from last weekend's National Garden Scheme trip. The RAW Dual-ISO, unrocessed, image looks like this:

That is, not very impressive. If we zoom in to an area of the image we can clearly see the Dual-ISO 'bracketing':

BTW the image was captured handheld on my 5D3 at 24mm, F/13 and with an ETTRed shutter of 1/160 sec. Using ETTR I was guaranteeing that the sky would not be blown out, and by using Dual-ISO I was giving the shadows a 3Ev boost at a Dual-ISO setting of 100/800.

After processing the Dual-ISO to a 16bit TIFF file, I played around a little with LR's sliders, eg bringing down the highlights and boosting the shadows. I then did a round trip to Photoshop and applied some local contrast adjustment, to bring a little pop to the image; ending up with this:

Bottom line: IMHO the Magic Lantern ETTR and Dual-ISO combination remains THE killer feature for still photographers.

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