Long exposure with 1/800 of a sec...

[ebojorq]

That's right, you can. I was reading about a feature in my camera that allows you to make an overlay of two images and still get a RAW file for post production. Actually I combined two techniques

What caught my attention, though, was the fact that I could get a long exposure looking shot in circumstances where there is too much light to do so or when you just don't have an ND filter to get through with a long exposure.

The result is this:


The camera is a Nikon D3100 and has an "Image overlay" function that does the same as more advanced cameras do but in a different (more annoying) way.

The setup for this technique is very simple and you just need to do a little very basic math:
1.- you take a first picture in order to set the exposure the way you want it, say f/22, @1/200 of a sec and ISO 400.
2.- Then you decide how many pictures are going to make your overlay. In this case 5

There are two ways to go from here (in D3100)

(This is the one road I took)
3.- You take every single picture with whatever settings you determined in step 1.
http://www.flickr.com/photos/ebojorq...n/photostream/

all five pictures where identical to one another, except for the position of the clouds and the waves.
4.- When you combine the picture with "Image overlay" option you set the gain of each original picture in order to get the appropriate exposure level.

(This is the "correct" one)
3.- You divide your original shutter speed by the number of pictures you want to combine together. This results in 1/1000 of a sec.
4.- There are two ways to do this step, depending on the camera you have. In the D3100 you enter in playback mode and press the menu button and look for an option called "Image overlay". You will be prompted to select two of your pictures and it will show you a preview. Depending on the number of pictures you want to combine, you will have to repeat this process as many times as you need to combine every new resulting image with the remaining original ones.

I hope I didn't make this terribly complicated and that you find this "technique" useful.


The two original articles are in Nikon's web page in the Learn & Explore section:
Image Overlay: The Lab on the Bus from Nikon
Multiplication Factor from Nikon

[simeon]

What you forgot to mention is that you must shoot the photos in RAW otherwise the will not work. I'm looking forward to using this technique on my new Nikon d3100.

[ebojorq]

You're right, Simeon... I forgot that part.

In other more advanced Nikons, the way you do it is when you are actually shooting the picture. You have to set something up in order to get a number of exposures in the same frame... I love reading manuals, but reading one of a camera I don't own nor plan to buy would be too much... even for me...