Sunday, October 27, 2013

My ML-enhanced High Dynamic Range (DR) Workflow

This post follows from the previous one. In this post I share with you my Magic Lantern (ML) enhanced workflow.

I assume the reader is familiar with ML, Advanced Bracketing, Auto-ETTR and Dual-ISO. If you are not then start here:
So here is the workflow:
  • Enable the appropriate modules, eg Auto-ETTR and Dual-ISO;
  • Compose and focus the scene and assess the DR of the scene, either using ‘guess work’, in-camera metering (ML or Canon) or use an external meter ( I use an Sekonic L-750DR);
  • Based on your metering decide on one of the following basic capture strategies:
    • If the DR allows it, ie low and containable in a single image capture, use a single exposure and set metering handraulically using your photographic skills (in whatever mode you decide to use, ie Tv, Av or M). This is the non-ML-enhanced base approach; 
    • As above, but get some help by using ML (double-half press or SET, ie not ‘Always-On’ or Auto-Snap) Auto-ETTR (to obtain a single image capture) and ensure maximize the quality/quantity of the image file, ie maximize the number of useful photons captured and converted, without blowing out highlights. A further refinement here is to switch on dual-ISO as well, but I prefer not to use this as part of my photographic workflow; 
    • Use Auto-Snap or Always-On AETTR and first meter for the highlights you wish to ‘protect’ (recompose as required) and use this as the starting image for the AETTR capture. Using this approach you will get two images, one with good highlight capture and the other with, likely blown out highlights, but with good shadow/mid exposure (according to your AETTR settings), ie based on the AETTR algorithmics. This is a good strategy for capturing a two-image bracket set, ie as long as the scene’s DR is not too large for your camera. This two-image bracketing is fast and virtually guarantees you will never have blown out highlights that are important to you); 
    • Switch off AETTR (and dual-ISO) and switch on advanced bracketing and select the number of brackets to cover your metering or use the auto setting, which will mean more image captures will it will result in a full DR bracket set.
  • Ingest into Lightroom; 
  • For the single image captures I will then carry out basic LR processing as normal; 
  • For the two-bracket (auto-snap) capture I will adjust the images, eg to ensure good highlights in one and good shadows/mid-tones in the other. I will throw these two images down two post-processing paths. First I will use LR/Enfuse, and then I will use ‘Merge to 32-bit HDR’. I then have two image files to ‘play around’ with, a 16-bit one and 32-bit one; 
  • For the advanced bracketing set I will once again try several post-processing routes, eg Photomatx, HDR Efex Pro 2 or Merge to 32-bit HDR’;
  • In all case I will then usually go into Ps-CC and finish off the image with a variety of post-processing tools.
The attached image is one I took this morning to illustrate the ML-enhanced, AETTR, 2-bracket approach. Although not an award-winning image, it does show that all the highlights and all the low and mid-tones have been adequately captured.

So, in conclusion, I’m not saying the above is the THE way to go, but, for me, it works and I thank ML for that! For those with a Canon camera, I once again encourage you to explore ML, especially the nightly builds that include the AETTR module.

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