How to do HDR with long exposure photos?

Question

I've seen a lot of nice landscape photos on 500px that seem like there must be HDR or some process to blend in skies with the foreground, many also have long shutter speeds. Unless they are all using graduated ND filters, can HDR or some post-processing method support longer exposures and then hdr?

Answer 1

In principal the HDR methodology can be applied to exposures of any length. However longer exposures are more likely to contain motion which can cause problems for automatic exposure blending programs.

One commonly used solution is to manually blend the exposures by masking. Whether or not this counts as "HDR" since it doesn't involve creation of a high dynamic range intermediate image is a rather pointless debate on semantics.

Here's an example of manually blending exposures in landscape photography to overcome movement, original frames:

Building up the image by masking in successively brighter frames towards the foreground:

Answer 2

HDR can be done from as long exposures you can take with your camera (until teh battery runs out in bulb mode!). Unless you consider the 14bit image in the raw HDR, you need 2 or more exposures. How to achieve these exposures is your decision: 1. Shutter 2. Aperture 3. ND filters 4. ISO. The 2nd choice is the most tricky as it changes the DOF.

The HDR method is the same no matter how you achieved the different exposures and no matter how long the exposure was. However, the longer it is the more you risk that something moved. So you should take the shortest exposure first and move up, if you use the shutter method.

If you are concerned that the flowing water till be sharp in one exposure and blurred nicely in another, the combined image can indeed look weird. Here the ND method or ISO method will be good.

If you still like the shutter method you can ensure that the short shutter exposure gets a really low weight in the computation of those flowing water areas by setting the exposure fast enough that the water is very dark. Then its pixels have close to zero weight and only the blurred shot will be seen.

Answer 3

If your camera supports it, it could be as simple as doing your long exposure as a multiple exposure (where you do multiple exposures of the same RAW). If you save the result in between each step, you should be able to progressively build a dark, medium and bright image or any other number of images in between as you develop each successive additional exposure.

Answer 4

It's kinda muddy subject already, but I was thinking the same thing. I'm trying to take a long exposure HDR night panorama, I googled that with no luck. After reading all your opinions I think the best thing to do is to take 3 bracketed shots and a long exposure and substitute the 0 EV with the long exposure, to make a long exposure HDR. I've already done this and got a very nice result which looked more like long exposure than HDR which I find more realistic.

Answer 5

If you can see full EXIF info including Tv and Av, then probably only a single exposure was used. Of course a single 14-bit RAW file can contain as much dynamic range as a -3, 0, +3 jpeg series. Most HDR software will allow you to tone map a single image and the result will look like it has been "HDRed".

Strictly speaking, High Dynamic Range imaging can be defined much broader than the 32-bit floating point digital image tone mapped to fit in 8 bits that we refer to as HDR today. The first known instance of combining different parts of two exposures, one light and one dark, to produce a single print of a seascape was in 1850. The dodging and burning that Ansel Adams raised to an art form was a method to coax all of the higher dynamic range available in the negative to the less capable print. Many have used layers in Photoshop and other imaging programs to combine the lighter elements of a dark exposure and the darker elements of a light exposure to produce a lower contrast image that contains dark foregrounds with bright skies. Others have taken a single RAW file, produced several images from it at varying exposure levels and then combined them using layers in the same way. The next hot buzzword, Exposure Fusion, is just another form of HDR imaging.

There is nothing inherent in HDR processing that allows recovery of blown highlights. If the highlights are clipped in the RAW data, they are gone and the information no longer exists to recover them. If, on the other hand, the highlights appear clipped in the jpeg thumbnail or preview 8-bit rendering of the RAW file, the actual file may still contain the information needed to recover them. If so, they can be recovered by any conventional raw editing/conversion software that allows the white point to be adjusted and the response curve (often called gamma correction) to be altered.

Can HDR or some post-processing method support longer exposures and then hdr?

If images are taken at longer shutter speeds and wider apertures than the lighting would normally indicate without clipping the highlights, some form of density filter needs to be used. This is equally the case whether the raw data is post-processed conventionally or using an HDR application.