Monday, October 9, 2017

Focus Shift Photography with the Nikon D850

The Nikon D850 comes chuck full of new features some of which are a big surprise. Stack focus photography is something I have been doing for years on certain still life subjects, but I had been resorting to a manual re-focus of the camera lens to shift the focus point after each shot. Needless to say, when moving the focus in very small increments -- in  my case, usually taking 20-30 photos with under 1" increments between them -- it is very difficult to maintain consistent distances between each shot. There is now software, Helicon Remote by Helicon Soft, to deal with this, but it is only available with tethered shooting.

Nikon's D850 now comes with the ability to automatically do focus shift photography.  You must use either AF-S or AF-P lenses for it to work. Otherwise the camera cannot move the focusing mechanism in the lens.

Click here to download a high screen res version of this image. 
For this type of photography I generally use a focal length of 50-85mm and an f/stop of f/5.6. I find that f/5.6 delivers just enough focus area between shots, and additionally has the lens working at its resolution sweet spot.

The camera menus below show the setting I used to achieve the still life photo above.  There is no supplied information on what size the focus steps are. There is only a scale of 1-10 from narrow to wide. I did some trial-and-error experimenting to find that I needed the lowest step setting of 1 and 23 shots to cover the distance from the front of my set to the back. The actual distance of my set from front to back was about 23" so that would mean that my setp width setting of 1 was moving the focus distance 1" between exposures. None of the remaining options on the menu were applicable to my situation so that was it. I clicked on "Start" and after a 3-second delay the camera took all 23 images with the proper increment between them.

Needless to say, the camera should be on a tripod for this type of shooting.

I should also mention that the camera was in AF mode so I did a manual re-focus on the closest foreground object in the set, which was the detailed white napkin. When propping these sets, I always try to include highly detailed props such as this to play up the overall look of sharpness.

One tricky thing I did have to do was deal with the bubbles in the champagne glasses and orange juice pitcher. These bubbles dissipated by the time the camera exposure was located in their position. So, once the photos were taken, I then refocused the camera on each of the glasses and the pitcher and took an additional exposure of each with a new pour of the liquid to produce the bubbles. I then added the bubbles into the final image with Photoshop.

To assemble the 23 images into one photograph I used Helicon Focus software. It is a very easy, drag-and-drop software to use, and will accept even the RAW files, which I used here. 

I have been saying that the new Nikon D850 has reached a new pinnacle of sophistication for DSLR cameras.  The most recent sensor testing results by DxOMark has borne this out. DxO has given the D850 a rating of 100, the first time this maximum rating has ever been given to a camera sensor. DxO said what I have also been discovering, that the new BSI sensor in the D850 is capable of producing medium format quality images.

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