Pages

Saturday, 12 August 2023

Panasonic Lumix FZ1000.2 Focus bracketing for increased depth 12 August 2023

 

Photo referred to in the text


This is referenced on page 142 of the Advanced Operating Instructions for the FZ10002. The instructions lack detail so here is some more information about the process.

If we want to make a photo in which everything from the foreground very close to the camera to the distant background is sharp, we can close down the lens aperture or utilise focus bracketing and stacking to output a composite image.

The FZ1000.2 has a sensor 8.8 x 13.2mm in size, giving a diagonal of 15.9mm. This is considerably smaller than  the 24 x 36mm or 14.9 x 22.3mm sensors found in most mirrorless interchangeable lens cameras (MILC).

For any selected aperture (expressed as f-stop) the smaller sensor will give greater depth of field than the larger sensors.

However the more we close down the aperture seeking to increase depth of field the closer we approach an aperture which is so small that it adversely affects sharpness due to diffraction of light rays passing through the small aperture. On the FZ1000.2 loss of sharpness due to this effect begins around f8 can readily be seen in closely scrutinised photos at about f11.

I find that most landscape photos can be made with a single exposure at 9.1mm (25mm equivalent) at f8, delivering sufficient depth of focus and also good sharpness.

Depth of field at focal length 9.1mm and  f11 extends from about 400mm to infinity. In other words from very close to the camera to the horizon. But we cannot achieve maximum sharpness at f11. This is when focus bracketing can be useful.

We might also find focus bracketing useful when working at longer focal lengths which deliver a shallower depth of focus.

For the worked example shown here I selected RAW capture, focal length 35 indicated, actual focal length 12.6mm and f5.6,  set A on the Mode Dial, Timer delay 2 seconds, Stabiliser off. I used a tripod which is best practice although if we have steady hands we can try without the tripod with the stabiliser on, and hope Photoshop can successfully align the images in post processing.

I allocate Bracketing to My Menu for easy access and in this case I set Step 5, Image Count 5, Sequence 0/+.

The only rule for determining the best Step level and Number count is trial and error, with each focal length and subject having a different requirement.  Broadly stated, if the focal length is short (wide angle) and the distance to the closest subject element is large we can use a small step and a small number of frames. A longer focal length and a subject closer to the camera require more images and possibly a greater step size although that needs to be tested by trial and error.

I located the focus area lower left in the frame to focus on the foliage here which is only a few centimeters from the front of the lens.

I pressed the shutter button and the camera made 5 photos in quick succession each focussed at a greater distance than the previous one.

I transferred the files to the computer using Bridge downloader and selected all five in Bridge.  I checked that the first frame is focussed where I wanted it to be and the 5th frame is focussed on the foliage in the background.

This is the procedure for making an image composite in Photoshop:

* Transfer the selected files to Camera Raw, select all,  then apply the same adjustments to highlight, shadow, contrast, sharpness etc to each file.

* Open the selected files in Photoshop

* Go to File > Scripts > Load files into stack. Check add open files and attempt to automatically align source images. Leave the smart object option unchecked.

* Select all layers in the Layers tab

* Go to Edit > Auto blend layers > Stack images. Check Seamless tones and colors and Content aware fill transparent areas.

* This produces a composite file which combines the sharp parts of each of the source images.

* Close the source images leaving just the composite.

* Go to Layer > Flatten image

* Make any final adjustments as desired then save the image in any desired format.

Some cameras can automatically perform this process in camera to produce a composite JPG image but the FZ1000.2 is not one of them. However in my experience RAW capture and processing in Photoshop almost always gives a better result.

With experience and practice both capture and post processing become easier to manage.

 

 

 

 

No comments:

Post a Comment