HDR 3 (2 stops) or 5 (1 stop)

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Are there any differences between HDR from 3 pictures +-2 stops apart (-2;0;+2) vs. 5 pictures +-1 stop difference (-2;-1;0;+1;+2)?

In both cases the pictures are from -2 to +2 stops. Are there any difference in results or in calcullation inside Photoshop (or Camera Raw)??

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D Fosse

Community Expert

The important thing is to utilize the full sensor data (ACR), instead of merging rendered RGB data which is gamma encoded and dynamically clipped to about 8 stops.

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Conrad_C

Community Expert

You might find some guidance by going to the Adobe link below, and scrolling down to the heading “How many photos are required to process a quality HDR merge?”

https://helpx.adobe.com/photoshop/using/high-dynamic-range-images.html

It contains a table and some advice about the optimum number of exposures depending on how many stops apart the darkest and lightest exposures are. And also how if a low exposure difference makes it practical to merge fewer exposures (such as when 2 is enough instead of 3), you should do so because merging fewer images lowers the chance of misalignments.

I don’t know what the calculation differences are between HDR merging in Camera Raw and Photoshop, but I think that controlling the result is easier using Camera Raw edit options compared to using the older Merge to HDR Pro dialog box in Photoshop.

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D Fosse

Community Expert

The endstops determine the total dynamic range, identical for these two.

If you're working from raw files, a good modern camera sensor already has a native dynamic range of around 14 stops. So there should normally be plenty enough overlap for 3 exposures to cover a 4 stop bracketing range. Obviously, this depends on the scene, but I can't see many situations where you would realistically need 5 exposures.

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Ferd1Author

Participant

That is the exact reason for my question. If camera dynamic range is 14 stops, there is no reason to have 3 or 5 exposures. 2 exposures should be enough. +-2 stops (or +-5 or any higher) for example.

The middle exposure doesn't need to be included in case of 3 exposures.

And the 3 middle exposures (-1; 0;+1) doesn't to be included in case of 5 exposures.

Simplify it: for any scene with dynamic range up to 28 stops (=2x14) should be 2 exposures enough... Why not???

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Conrad_C

Community Expert

Adobe agrees in another article they published, High Dynamic Range Explained:

Keep in mind that a single raw file can hold a lot of dynamic range already, so it’s not always necessary to use exposure bracketing and the Merge to HDR feature.

I do find that when I have my camera take an exposure-bracketed set of three, sometimes when I look at the images I find that everything I want is in within the dynamic range of just one of the frames. The main reason to include another frame in the bracket is in case I want to bring up more shadow detail with less noise.

By the way, that article is especially useful if you want to learn about every control in the powerful end-to-end HDR editing workflow in Camera Raw/Lightroom, because the lead engineer wrote that article when that complete workflow was first introduced two years ago. As D Fosse mentioned it’s better to edit HDR using raw image data instead of in Photoshop.

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