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Author Topic: Focus stacking with Fujifilm's GFX  (Read 1620 times)

Remko

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Focus stacking with Fujifilm's GFX
« on: November 24, 2019, 10:30:37 am »

I received a PM from one of the LuLa members asking about the focus stacking feature of the GFX. And after replying he suggested to post it here, so other members can benefit as well. Here it is:


My setup is as follows:

Frames: 99
Step: 5
Interval: 0

Frames
I choose such a high number as there were situations that I had set it too low, e.g. 29 frames = images. And the algorithm stops making images anyhow when infinity is reached. Really excellent. So for landscape photography you are safe with whatever high number you choose here.
I have been in a situation where I guessed I only needed 20 shots, when in reality I needed much more as there was so much foreground detail pretty close-by. I ran out of shots as I had set the number of frames too low. That costed me a wonderful shoot.

Step
This is the overlap - or lack of overlap - between the images you shot. See it as a physical layer in the 3rd dimension - so the depth of your final composite image - where each layer has a different focus point a bit further away from where the camera is. With “5” there is no overlap between the images and also no gap. With a lower number there is overlap, which really is not needed and cost you a lot of extra shots and the effort to determine which shots you can keep and which you can delete. A lot of work. With a number higher than “5” there is a gap between the images. With a gap I mean an area in an image where there is not sufficient sharpness. Fujifilm implemented it this way for macro photography: they say that in order to reduce the number of shots, you can have a higher step number. Otherwise the number of shots are in the hundreds.

Interval
I want the images to be shot as quick as possible to avoid any movement in branches and leafs. So I have set this to “0”. It is meant to avoid unsharpness due to e.g. shutter shock. But I can avoid that by either using the electronic shutter or by using the mechanical one with electronic front curtain activated. And I set the self-timer to 2 seconds, or to 10 seconds if I have a really long exposure time.

How Fujifilm focus bracketing works
The algorithm is impressive! It takes a lot of parameters into account. One of course is the chosen aperture. I choose the aperture that gives the best optical results and is outside diffraction territory. I use Capture One which has a superb diffraction correction feature, but still :-).
What is also taken into account is how close the first point of focus is to the camera! There is much more, like the focal length, but not everything is publiced by Fujifilm.

Focus point and size
When I was first testing the GFX50S I ran into the issue that the lowest focus point is still not low enough to get everything at the very near foreground in focus. Already with the 32-64 lens I ran into this getting closer to the longer end. It is a hardware limitation of the focus points. The way to get around this is to make the focus point as big as possible and leave it that way through out the shoot. That way the whole foreground outside the hardware limitation is covered. At first I found this counter intuitive, but it works excellent!
Another thing I ran into is that when the camera is not perpendicular to the subject, it is best to place the focus point to the nearest part of your subject = landscape. Otherwise that part will never get in focus.

Creating the final composite
I use HeliconFocus to create the final image. In my view an excellent piece of software. What is evenly impressive is Zerene Stacker. I never found Photoshop good enough for this, as with most of its features. And am not using it anymore and use Affinity Photo instead. But not for focus stacking.

Exposure for landscapes
If you are not using manual exposure, I get the best exposure for landscape photography by using “Average". I come from Nikon and their the exposure was much more spot on than what I got with Fujifilm. Until I realised that fujifilm’s “Multi” is quite different from Nikon’s Matrix metering - the latter being is excellent! I have way less to compensate - so I get less blown out highlights. In order to have the same exposure for the bracketing I shoot manual - I do not want the exposure to change somewhere during the shots.

Enjoy your journey :-)

cheers,
Remko
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Jim Kasson

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Re: Focus stacking with Fujifilm's GFX
« Reply #1 on: November 24, 2019, 10:38:57 am »


How Fujifilm focus bracketing works
The algorithm is impressive! It takes a lot of parameters into account. One of course is the chosen aperture. I choose the aperture that gives the best optical results and is outside diffraction territory. I use Capture One which has a superb diffraction correction feature, but still :-).
What is also taken into account is how close the first point of focus is to the camera! There is much more, like the focal length, but not everything is publiced by Fujifilm.

The algorithm operates in the image field, so focal length and object-field focus point is unimportant. It holds the CoC constant as you change apertures.

Details here:

https://blog.kasson.com/gfx-100/quantifying-the-fuji-gfx-100-focus-bracket-step-size/

Jim

Paul2660

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Re: Focus stacking with Fujifilm's GFX
« Reply #2 on: November 24, 2019, 11:08:40 am »

Thanks for the info. 

Personally, I have been able to manage with a lot fewer images, and in pretty much all my subject matter 50-99 images would have some form of motion involved due to wind (99 percent of the time).  Helicon, even latest version can't handle motion of leaves, or tree limbs and creates artifacts which I feel can't be removed. 

It's a matter of time also, as stacking 99 100Mp files in any PC or Mac is pretty time consuming process. At least of for me.

I realize that many on this site are hung up on diffraction softness issues, so I won't belabor that point, however I have been pleased with most of my images from the GFX100 within F11 to F8, and 10 images without bracketing for focus and when needed usually 5 to 10 images will get a satisfactory result for my subjects. 

As you point out, it's quick and easy to implement and good point on the large focus point, to get the lowest possible location on a subject.

Paul C
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Paul Caldwell
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www.photosofarkansas.com

kers

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Re: Focus stacking with Fujifilm's GFX
« Reply #3 on: November 24, 2019, 11:47:22 am »

It's a matter of time also, as stacking 99 100Mp files in any PC or Mac is pretty time consuming process. At least of for me.
Usually the stacking stops at infinity so 99 is a maximum
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