Other Benefits of Long Exposure Time

Hello everyone, this my first post but it's not an introductory thread. I'm wondering if there are any "lesser known" benefits to using a long exposure time - that is, besides showing motion (waterfalls, people walking, stars across the sky, etc.).

The reason I ask is that while out taking photos the other day, I saw a noticeable difference in color saturation between photos with short exposure times vs. those with longer exposures. I *assume* it is because the sensor can pick up more color information over an extended period of time.

Here is a comparison for your reference... white balance was identical for both shots and both pictures are straight out of the camera (besides resizing for internet). As you can see the top image looks to be much more saturated, while the shot on the bottom is a bit washed-out.

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I think the bottom image is underexposed compared to the top one. Someone correct me if I'm wrong but to go from 1/6 to 1/60 shutter speed, you go down just over three stops. But to compensate in aperture size (f/8 to f2.7), you are only going up less than two stops.

So the image on the bottom is underexposed compared to the top one. That's the reason for the color difference.

Correction: Thanks Photosguy, f/8 to 2.7 is about three stops.

No. 2.8 to 4 to 5.6 to 8 = 3 stops.

PhotosGuy wrote in post #7381448
No. 2.8 to 4 to 5.6 to 8 = 3 stops.

whoops, yes you are correct....sunday the brain takes a day off too!

There are two factors that I see here.

For one thing, the lens could be producing better color and contrast when stopped down a little more. That could easily contribute to the better quality in the first image.

Second, there is definitely a greater depth of field in the first (stopped down) image. That makes the leaves in the background appear sharper and more defined.

Although it was stated that the white balance was the same for both images, there is a very significant difference in the color between the two shots. What was the white balance setting for the two images? If it was AWB (Automatic White Balance), it's easy for the camera to read the color a little differently for the two shots.

SkipD wrote in post #7382047
For one thing, the lens could be producing better color and contrast when stopped down a little more. That could easily contribute to the better quality in the first image.

Yeah, it's not the longer shutter speed that contributed to the better colors. If the OP had stuck an ND9 filter and shot f/2.8 and 1/6, it would have not had the better color and contrast that the f/8 and 1/6 image had. The contribution comes from the aperture being stopped down, not the longer shutter speed.

Alright, thanks everyone. I might try doing a few tests with an NDF to see what kind of results I get.

I dont think longer exposure itself should yield any IQ benefits. But let us know!!

Longer exposures are necessitated by less light reaching the sensor. That means the dynamic range of the illumination is down in the low end of the sensor sensitivity. Sensors may have some effects as a result, but actually I find that, apart from noise, they tend to be fairly linear in their response. Film, on the other hands, is a mess of non-linearity.

The main difference is that a long shutter speed allows a small aperture, and that affects the image profoundly.

This image was made at f/16 and 6 seconds.