SNS-HDR Forum

I have a Canon 5D (Original version) that can only provide 3 AEB exposures of 2EV steps each. I expect to take pictures with higher DR, thus will make manual exposure "brackets" via shutter speed increases (dark to lightest) in series.

I have tried to translate the few guideline documents into English, and have read them through carefully, but still have a couple of questions.

1. is it recommended for the darkest exposure, for that exposure to be set such that it is exposed to the right (ETTR) such that no highlights are blown out, and just within the right side of the histogram, and then use 2EV brighter shutter settings to progressively lift the exposures until the darkest areas are well within the left side of the histogram?
I think I understand the calculations for the number of images needed for 2EV steps.
So my question is really...is there any benefit to taking any darker images than what I described above, or have I understood the recommended process correctly?

2. in terms of image quality, if the process means I need to use, say, 3-5 input images to cover the full DR of the image, is it best to use RAW input images, or TIFF, for the very best image quality?

3. Is it better or recommended to sharpen the individual images and do any noise reductions PRIOR to the SNR-HDR process, or best to leave the input images exactly as they are, and adjust afterwards? What about white balance/color changes, etc?

22 views and no responses? Perhaps my questions are unclear, or I'm being silly with them, but I really do THINK that knowing the answers will help me as a beginner with this program, if anyone can help?

Thanks all!!!

Barry

Barry,
Q1. This thread may provide some 'illumination'. Den has provided a lot of samples which address some of the questions that you have raised.
Q2. I don't know the answer to this. My own view is that high quality jpeg will suffice as having the range of bracketed exposures means that you are not dependent on getting the very last drop of information from a single shot when, of course, RAW is best.
Q3. If going from jpeg I adjust afterwards. If going from RAW I process to TIFF outside of SNS-HDR as I think that I get a better result, especially as far as noise is concerned. I use a RAW converter tailored to my camera (in my case Silkypix for a Panasonic GH2).

No doubt a bit of experimentation on your part will determine what works best for you.

Mike.

Thanks Mike!

In your response to Q1, you mention a thread which may help....did you mean this thread or some other thread? (I don't see any link, etc?)

Thanks again!


Barry

Sorry!

viewtopic.php?f=8&t=213

Mike.

very interesting! SO, if I understand that right, there is an output difference (of more than just a straight shift in exposure to the left), if we include a set of "balancing" darker exposures in the mix, even though a number of exposures may have no highlight clipping at all!

If I got this right, it means that I should NOT start with my darkest exposure set to the point where we are typically "ETTR" (with zero highlight clipping), but rather to use a spread of exposures that have roughly equivalent "margin" of headroom to the left and to the right, of the actual scene's DR. Does that sound right?

I'd always thought, after struggling through the translated text provided in the "Zero Noise" site, that there was really no point at all in having any darker exposure than one that easily contains the brightest highlights, and to simply expose more and more to cover the deep shadows until all shadows are within the sensor's left border (or perhaps slightly more, to help reduce noise).

hmmmm, I'm going to experiment a bit more tomorrow, with different starting shutters, zero processing in LR other than lens correction, then do a default HDR merge/process with SNS-HDR and see what the histograms look like.

Great topic, thanks.

Barry, I was of the same view as you as I think I expressed in that thread.
In theory there seems not point to going 'darker' than necessary.
In practice, as Den demonstrated, it does make a difference.
Not a life and death difference, but one that perhaps lessens the need for further processing.

Mike.