I have largely abandoned stopping the lens down to cover the depth of field for the several reasons listed below:
Stopping the lens down to f/16 and f/22 produces an overall less sharp image due to the optical effects of diffraction.
Stopping the lens down usually doesn’t cover the depth of field all that well anyway. Only where the lens is focused is it truly sharp. All other distances are subject to “acceptable focus,” and that isn’t exactly sharp focus.
Stopping down the lens to small apertures (f/16 for example) will cost you light. This means you must use a slower shutter speed or higher ISO to compensate.
If using flash, you get greater ability to light distant objects by not stopping down the lens as much. Focusing stacking lets you use a bigger aperture to allow the flash to light the object, and stacking covers the depth of field.
Even tilt/shift lenses don’t cover the depth of field like focus stacking does. Tilting the lens can help you make better use of depth of field, but it only works for one plane, not all planes found in the scene. Focus stacking works for all planes at once.
Here is a stacked image of snow on manzanita that I made at Red Canyon near Bryce.
Here is my procedure:
Compose the subject.
Determine the exposure by adjusting the exposure to produce the first blinkies – shooting RAW of course.
Use f/8 as a guideline, as that is a sharp aperture to use on most lenses. The sharpest apertures are about 2 to 3 stops smaller than the maximum aperture.
Use a magnified live view image on the camera’s LCD to focus on the closest point where sharp focus is desirable.
Put my hand in front of the lens and shoot the image to mark the start of the stack.
Shoot the first image.
Turn the focus ring on my lens manually, just a little, to focus a little further away, and then shoot the image.
Keep turning the focus ring a little (key word here is LITTLE) and shoot another image.
Keep doing this until the spot where sharp focus is desirable is covered.
Photograph my hand again to mark the end of the stack.
How many photos must be shot to cover the depth of field?
This is the most common question I get, and the answer is simple. Shoot as many images as necessary to cover the depth. There is no set amount. It depends a lot on magnification and what is desirable to be sharp. If the lens is already close to infinity focus when the stack is started, it won’t take many images to reach infinity. But, if the foreground is close – say only 3 feet – most likely it will take many more images to produce a successful stack that covers the depth.
What do I focus on next after the first image is shot?
Another common question that I find you can avoid. Once I start the stack, I don’t worry about where the focus lies. I merely move the focus ring in tiny increments and shoot the image at each focus distance and keep that up until I reach the background.
Processing the Stack
I shoot RAW images, so all must be processed. I am not a software guru by any means. Indeed, I am a processing infant who can use Canon’s free Digital Photo Professional 4.7.1 software rather well, but that is all I know about processing. If I have a stack of say – nine images – I process one image and save it. Then I COPY RECIPE, highlight the other unprocessed images in the stack, then PASTE RECIPE, and SAVE. Now all images in the stack look alike. To make the image ready for posting on the Internet, I then highlight all the images, go to BATCH PROCESS, and covert all the RAW images to JPEGs with the long side set to 2048 DPI and the short side proportional to that.
Now I open my stacking software – Helicon Focus – highlight all the images in the stack that are now converted to JPEGs, and Render them with Helicon Focus, and Save the result. It only takes me a few minutes to do this whole procedure.
Here is my EXIF data for the Snow on the Manzanita image.
File Name Manzanita with snow 7fs done 2018-02-23 04-57-37 (B,Radius8,Smoothing4).jpg
File Size 2.7MB
Camera Model Canon EOS 5D Mark IV
Shooting Date/Time 2/20/2018 9:34:19 AM
Author JOHN GERLACH
Shooting Mode Manual Exposure
Tv(Shutter Speed) 1/13
Av(Aperture Value) 10
Metering Mode Evaluative Metering
ISO Speed 100
Lens EF24-70mm f/2.8L II USM
Focal Length 70.0mm
White Balance Mode Auto: Ambience priority
AF Mode Manual focusing
Picture Style Standard
Drive Mode Self-Timer Operation
Live View Shooting ON
Several images were shot to focus stack this scene at White Pocket in Arizona.
These are hoodoos at The Toadstools between Kanab, UT and Page, AZ. Five images were shot to focus stack this scene together to cover the depth of field.
Above is a shooting star flower shot at f/22. Due to diffraction, it isn't quite as sharp as the one below this one that is shot at f/8 with 12 images stacked together to cover the depth in the flower better and to use a sharper aperture of f/8.
A highly cropped portion of the flower shot at f/22. Notice the much less detail in the flower bud in the middle of the image.
Twelve shots made at f/8 and stacked with Helicon Focus. Notice the more apparent detail and crisper look of the detail. Noticed the flower bud in the middle as the red dots are more apparent. Both the stacked final image at f/8 and the f/22 image were processed the same with Canon's DPP4.9.2