Luminous Landscape Forum
Equipment & Techniques => Mirrorless Cameras => Topic started by: Chris Kern on July 23, 2018, 03:40:59 pm
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I finally got around to trying out the new focus-bracketing feature introduced by the version 4 firmware for my Fuji X-T2 and I must say I'm favorably impressed. I don't have much experience with macro photography in general or focus-stacking in particular, but being able to automate the captures without having to move the camera brings the technique into the range of my limited skill level.
One question: has anybody figured out the semantics of the step value in the focus-bracketing menu, and how or whether it relates to the focal length of the lens or the distance between the lens and the subject? The explanation in the manual (see below) is not very useful.
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Some discussions here: http://forum.luminous-landscape.com/index.php?topic=124652.20
No, I didn't figure it out exactly the numbers but I think they depend at some extent on the focal length. I don't think there will be a clear answer out there.
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Some discussions here: http://forum.luminous-landscape.com/index.php?topic=124652.20
Thanks. I'd forgotten about that thread—even though I contributed to it! Senior moment, I guess.
No, I didn't figure it out exactly the numbers but I think they depend at some extent on the focal length. I don't think there will be a clear answer out there.
This is the kind of inadequately-documented feature I find very frustrating. I'm sure there is an engineering document somewhere in the Fuji bureaucracy that explains how the step function works. It should be possible to remove any proprietary information, clean up the prose, and provide some guidance that would help users exploit the capability optimally.
I'll try contacting Fuji-USA customer service to see if they can provide any useful information, but I'm not particularly optimistic.
Having said that, I'm not discouraged by my trial-and-error results.
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One question: has anybody figured out the semantics of the step value in the focus-bracketing menu, and how or whether it relates to the focal length of the lens or the distance between the lens and the subject? The explanation in the manual (see below) is not very useful.
Nope. I'm still experimenting and erring on the side of too many shots but the results have been good.
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I'm still experimenting and erring on the side of too many shots
That's what I did, as well, in my tests. To make the sunflower pictures I attached to the first post in this thread, I used Photoshop to stack 30 raw files captured at bracket step-level 3 (whatever that means) after importing them from Lightroom. I suspect the composite would have been just as good with 20 captures if I had known how optimally to set the step value in the camera.
With 30 images, the processing bottleneck seemed to be the time it took for Photoshop to collect the raw files and render them as layers. Aligning the layers and creating the masks to perform the focus-stacking was surprisingly fast. (Using a 6-core 2013 Mac Pro with 64GB of primary memory, in case that's relevant.)
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Another focus-bracketing experiment.
My wife bought some "Japanese yams" at a local Asian supermarket, but we never cooked them and they sprouted. Before discarding them today, I took them outside, sat them on our glass patio table, and shot a focus-bracketed sequence with my X-T2.
Once again, 30 frames at bracketing step 3 (whatever that means). These were made with the Fuji 55-200mm zoom at 86mm and f/7.1; the metadata don't include the distance to the subject, but I think it was roughly 5 feet/1.5 meters. The subject was quite complex, with features occupying and occluding each other in several different planes. I stacked the captures with Helicon Focus, Method C: I downloaded the trial version of the Helicon product after my attempt to process the stack with Photoshop produced some out-of-focus areas.
I'm still hoping to find a Fuji customer service rep who can explain the semantics of the focus-bracketing parameters. In the meantime, I'm flying blind when I position and configure the camera. This picture turned out fairly well, but I'm afraid I have to attribute that to dumb luck.
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Nicely done, Chris.
With a start at the nearest focusing point you choose in your camera, 3 seems like a good choice. As the meager instructions say, the shot count stops when focus gets to infinity regardless of the number of frames chosen. So if you've set up for 30 and it only takes 10. That's a sign of how to approach a similar scene in the future. I see no downside though to configuring for 20 or 30 shots and not needing them.
All we can do at this point is to actually judge by how many of the shots were taken vs what we set it up for.
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Nicely done, Chris.
Thanks, Ron. Although as I said in my earlier post, getting the parameters right for that shot was just dumb luck.
I've been told to keep an eye out for an article on focus-bracketing that will be posted to the Fujjifilm X GFX website (https://fujifilmxgfx.com/). Hopefully it will include some information on how to estimate the optimal number of frames and step value for a particular subject based on the focal length, aperture, and subject distance — or some combination thereof.
Stay tuned. . . .
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I've used it a few times and it works well with the X-H1.
It may be useful to do a few experiments with the camera locked down on a tripod and tilted slightly down, say aiming at the front edge of a table top. Lay a yardstick (or a meter stick if that's how you roll) on the table top receding away from the camera and focus at a fixed point on the yard stick (say, maybe 3 or 4 inches from the leading edge of the stick). Then shoot a fixed number of shots (15 maybe) at a few different step choices (1, 5, 10) for a few different lenses or focal lengths and see if you can extract some sort of relationship between focal length and step size in terms of the movement of the focus plane as shown on the ruler. Crude, but maybe useful?
Kirk
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Lay a yardstick (or a meter stick if that's how you roll) on the table top receding away from the camera and focus at a fixed point on the yard stick (say, maybe 3 or 4 inches from the leading edge of the stick). Then shoot a fixed number of shots (15 maybe) at a few different step choices (1, 5, 10) for a few different lenses or focal lengths and see if you can extract some sort of relationship between focal length and step size in terms of the movement of the focus plane as shown on the ruler. Crude, but maybe useful?
Yes, I think it might be possible to make an initial stab at reverse-engineering the Fuji focus-bracketing step algorithm with a protocol along these lines. It probably also would be necessary to vary the aperture and distance-to-subject in order to identify and capture the variation among all the possible parameters, wouldn't it?
But I don't know whether this type of experimental approach, even if carried out fastidiously, would be sufficiently comprehensive to yield enough information to eliminate guesswork when actually shooting photographs.
It would be a lot easier if Fuji would (1) tell us precisely what parameters the camera firmware uses to calculate the focus-shift for a given step value and how the algorithm uses them or—if the company considers that proprietary intellectual property—(2) at least provide sufficient guidance to turn an uneducated guess about which step value to choose in a given situation into an educated guess.
I've made this request to the Fujifilm employee who is writing the article on focus-bracketing that I mentioned in an earlier post. No response yet, but I'm hopeful: my impression is that Fuji has been considerably more open with its customers than some other manufacturers.
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" It probably also would be necessary to vary the aperture and distance-to-subject in order to identify and capture the variation among all the possible parameters, wouldn't it?"
My thoughts too. A yard or meter stick would be good considering macro or close work... but a landscape is another thing. Could be more a matter of field testing rather than guidelines.
Impressed generally on a quick test, had objects as close as a 18" and as far as a distant shore all crisp in the same shot after processing. Lots of detail along the way. Shot with the 10-24 at 24mm and at f4. Put in for 30 shots, step of 5, 1 second apart. The camera shot 19 frames before stopping, assembled in PS, I tried Affinity auto stacking while I was at it, but didn't do as good a job as PS.
I think I'll do a proper test with the 35 1.4 and the 50-140, the lenses I usually use.
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For the GFX, but some insight:
https://blog.kasson.com/gfx-50s/gfx-fw-3-0-focus-bracketing-with-the-120-4-macro/
Kirk
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Thanks, Kirk !!!!
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For the GFX, but some insight:
https://blog.kasson.com/gfx-50s/gfx-fw-3-0-focus-bracketing-with-the-120-4-macro/
Quite an impressive analysis, but even so, as he points out in a follow-up post (https://blog.kasson.com/gfx-50s/focus-stacking-with-the-gfx-50s-a-demo/), "it's hard to figure out where the camera is going to focus at the end of one of these runs."
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The best way would be to set the start and stop points, aperture and let the camera figure it out how many steps are needed.
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The best way would be to set the start and stop points, aperture and let the camera figure it out how many steps are needed.
Yes, unquestionably. And even if that required a lot of processing cycles, it's not a real-time operation, like autofocus, so presumably it ought to be practical for Fuji to implement with current hardware.
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Dan Bailey reports on his testing of this on his blog.
http://danbaileyphoto.com/blog/how-to-use-fujifilms-new-focus-bracketing-feature/?awt_l=KD1RE&awt_m=3iSgbKgfzSmKiyM&tl_inbound=1&tl_target_all=1&tl_period_type=3
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Regardless of the option chosen frames end when lens reaches infinity.This is great for landscapes where the infinity is visible but for your example of tabletop you cant see infinity and Fuji provides a stacking system that has no xyz points pre configured. I would say its best use is to automate bracketing from the 1ST or front focus point in your choice of steps. The issue will be when the steps are going around a curve and the angle is variable... meaning the focus steps must be smaller to catch the curve in perfect focus as the fall off becomes greater.
I would not use any lens but a macro which has a flat field. I would not use stacking in PS it has never worked well. I would use Zerene Stacker https://zerenesystems.com/cms/home or Helicon Focus https://www.heliconsoft.com/store/.
You also need a way to provide a time between shots for camera vibration to settle if not you have a fair amount of work to eliminate the shake blur.Of course goes without saying Shoot at the smallest F-Stop you can without getting diffraction...and never never allow the F Stop to change during the course of capture.
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I've noticed that on Fuji X-H1 the amount of focus movement depends on the selected aperture: all other parameters being equal, the focus moves slower with wide open aperture.
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Re comment by BAB about camera vibration. Using the electronic shutter, I have not experienced any sign of this using zero time between shots.
Best wishes,
Jonathan
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Re: BAB
You do have an "INTERVAL" that can be set between shots that you can set if you're concerned with shutter shock on the X-T2. I've experimented on several occasions and noticed no vibration with the mechanical shutter. Most of the time I just set the "INTERVAL" or 1 or 2 to be safe. Other times I use the electronic shutter. I am not using a macro lenses close up so that may be a factor.
A friend of mine who does use his 80mm macro up close on botanicals highly recommends using C-AF if there is any movement.
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. . . has anybody figured out the semantics of the step value in the focus-bracketing menu, and how or whether it relates to the focal length of the lens or the distance between the lens and the subject? The explanation in the manual . . . is not very useful.
I've been told to keep an eye out for an article on focus-bracketing that will be posted to the Fujjifilm X GFX website (https://fujifilmxgfx.com/). Hopefully it will include some information on how to estimate the optimal number of frames and step value for a particular subject based on the focal length, aperture, and subject distance—or some combination thereof.
The article I was told to watch for back in August finally has been published (https://fujifilmxgfx.com/x-techniques/advanced-technique-focus-bracketing-with-fujifilm-cameras/) and it does indeed provide some useful information about the relationship between the step value and the subject, albeit expressed with respect to depth-of-field—i.e., a derived value—rather than focal length, aperture, and subject distance, which can be directly ascertained:
When using the Focus Bracketing feature on FUJIFILM cameras, users can set the Step value from 1 to 10. The Step is calculated using the distance between the near and far limit of the depth-of-field on the first image captured. Setting the Step to 1 moves the focus by approximately 20% of that distance. A Step of 5 moves the focus by around 100% of that distance. As an example, if the difference between the near and far limit of depth-of-field is four feet, a Step of 5 would move the focus point four feet for each shot.
Still, this a better than nothing and, with a little bit of effort, it should be possible to craft a software tool that would inform the user what step value and frame count were appropriate to keep the subject in focus.
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Congratulations to Fuji for being the first to implement this extremely useful function. This should be available in all AF cameras.
I think the optimal solution from the photographer's point of view would be
1) set start focus (manually)
2) set end focus (manually)
3) set number of frames
3a) (optional) set time delay between frames
4) go
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Congratulations to Fuji for being the first to implement this extremely useful function. This should be available in all AF cameras.
<snip>
M43 cameras had focus bracketing for quite a while and D850 has it as well. Surprisingly, latest Sonys still don’t have that feature.
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I am late to this discussion, but Micro 4/3 cameras have led the way with focus stacking, in camera. Fuji is playing catch up - which is great to see.
Panasonic and Olympus have been at it for a while, they use two different approaches. The Fuji approach seems much closer to what Olympus does. So videos on the Olympus (https://www.bing.com/videos/search?q=olympus+fopcus+tsacking+youtube&FORM=HDRSC3) focus stacking feature may assist the OP.
Panasonic cameras like the G9 and GH5 have two options for stacking. One is called Post Focus and the other is called Focus Bracketing. Focus Bracketing is similar to what Olympus and Fuji offer. But the Post Focus feature is so fast and powerful I have not used Focus Bracketing.
Post Focus is a two-stage process. After placing the camera in Post Focus mode and pressing the shutter release the camera finds all the focus points in the image and then takes a 6K video of all those focus points. The process takes about 2 seconds after pressing the shutter release. The lens must be in autofocus mode. You can create a focus stacked image in-camera using the G9’s touch screen or use a program like Helicon Focus. Helicon Focus imports the frames from the 6K video and you choose which frames to stack. You get a 18meg jpg in camera or a 50meg (approx.) TIF from Helicon Focus.
The challenges around the Fuji mostly concern DOF issues. A macro DOF calculator or a DOF Table may help. These types of discussions occur over at Helicon (https://www.heliconsoft.com/forum/) when using the Helicon FB Tube and also in the micro world, see here (http://www.photomacrography.net/forum/index.php).
FF mirrorless cameras are far behind with only Nikon and Phase One offering choices, that I know about. Older Sony cameras can use a very basic focus stacking app (which you must buy) but it does not work with the current A9 or A7 series.
For the last 2 months I have been revising my infield focus stacking technique using Post Focus and working out how to best post process 6K videos. The journey is documented here (http://www.photomacrography.net/forum/viewtopic.php?t=37904&highlight=).
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There is another way which I have successfully used with a DSLR to work out how many shots to take for a stack. Set the lens to manual focus, turn on focus peaking in the camera and use Live view.
Now turn the focus ring on the lens back and forward so the focus moves across the subject, and watch the focus peak colour move across the subject and work out how many shots you need with an overlap in focus between the shots.
That whole process was manual, but you could go back and switch to the Fuji in-camera stacking mode and enter the number of shots (remember to switch the lens to AF). Over time I found I could work out the number of shots required simply by looking at the scene (mostly flowers and the like).
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I think the optimal solution from the photographer's point of view would be
1) set start focus (manually)
2) set end focus (manually)
3) set number of frames
3a) (optional) set time delay between frames
4) go
Yes! I think the specific procedure should be something along these lines:
- Fix the location of the camera.
- Manually set the desired aperture.
- Manually use focus-peaking to enter a parameter representing the nearest part of the subject to appear in-focus.
- Manually use focus-peaking to enter a parameter representing the farthest part of the subject to appear in-focus.
- Manually enter a parameter representing the desired location of each successor frame's focus point (e.g., 25 percent of the computed depth-of-field behind the focus point of the current frame).
- Optionally enter a parameter for the number of seconds to delay between frames.
- Manually refocus on the nearest part of the subject.
- Trigger the camera to dynamically compute the depth-of-field of each frame and automatically shoot the required number of frames until it reaches the farthest focus point.
This doesn't seem to me to be all that difficult for a firmware developer to implement. Or am I missing something?
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There is another way which I have successfully used with a DSLR to work out how many shots to take for a stack. Set the lens to manual focus, turn on focus peaking in the camera and use Live view.
Now turn the focus ring on the lens back and forward so the focus moves across the subject, and watch the focus peak colour move across the subject and work out how many shots you need with an overlap in focus between the shots.
That whole process was manual, but you could go back and switch to the Fuji in-camera stacking mode and enter the number of shots (remember to switch the lens to AF). Over time I found I could work out the number of shots required simply by looking at the scene (mostly flowers and the like).
Using the focus peaking in manual mode is the easiest way to get the fewest shots or have DOF only in the area that you want. I get the feeling though that the software does a better job at stitching if the steps are the same, didn't properly test it though and it's unlikely I'll have the drive to do it.
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Fuji does not add this feature to the X-Pro2. Their tech folk say it can be done, their Corporate types say "X-pro people don't use their camera that way - buy an X-T2".
Can't stand the electronic finder and the X-T2 uses it.
Funny that those of us with the X-pro cameras expect them to be usable for all types of photography while Fuji does not.
I know it was not a feature when the camera was purchased. It was not with the X-T2 either. Firmware update added it.
If i have to get a "slr" style to use it I'll dump Fuji and buy a Nikon D850. Would rather have it on the X-Pro2.
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Here's a Fuji tutorial that I've just recently seen. I apologize if this is an old article.
https://fujifilmxgfx.com/x-techniques/advanced-technique-focus-bracketing-with-fujifilm-cameras/
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Sure wish the Fuji article would say if they recommend AF or MF while using this feature.
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Help me understand where you're coming from.
Are you questioning if you should or should not use MF for the starting point of the bracketing? That should be easy to test. Have you tried MF as your starting point? Did it work for you?
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Does anyone know why FujiFilm removed their focus bracketing document? Or maybe they moved it? I can't find any good information except at Nikon's site! I wish Fuji would publish good information about Focus Bracketing. I don't like guessing at the numbers. I am using 20, 3 0 for most landscapes at it seems to work well but I'd like to be able to figure out what STEP should be for a given scene and it'd be great if Fuji could provide a technical document on this. Nikon did a nice job on theirs - but it could be more thorough I suppose.
Here is where Focus Bracketing info was...
https://fujifilmxgfx.com/x-techniques/advanced-technique-focus-bracketing-with-fujifilm-cameras/
Nikon:
https://nps.nikonimaging.com/technical_solutions/d850_tips/useful/focus_stacking/
https://www.nikonusa.com/en/learn-and-explore/a/tips-and-techniques/focus-shift-the-basics-stacking-focus.html
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Help me understand where you're coming from.
Are you questioning if you should or should not use MF for the starting point of the bracketing? That should be easy to test. Have you tried MF as your starting point? Did it work for you?
I would ALWAYS use MF for focus bracketing. I learned this when photographing sand dunes where the camera can't always focus on something because sand does not have a lot of contrast except when there are a lot of shadows. If you use AF sometimes the camera cannot auto focus on some areas in the scene.
The fact that FujiFilm's GFX 50s can use MF while focus bracketing is a great thing! (I think Nikon requires to be in AF mode).
After you focus on the near spot the Fuji camera doesn't need to AF on anything while it focus brackets. It just moves the focus up by the STEP amount each time not worrying about actually focusing on a spot. That is brilliant actually!
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Hi, David,
I am quite confused to understand your notes. I thought the camera should be set for autofocus in order to do the focus stacking. Under the manual focus mode how the camera moves the focus points from the nearest to the infinity? Or did I miss your points? I would appreciate clarification. Thank you.
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I might be wrong but my camera is set to manual focus so I am assuming Focus Bracketing works in MF. It doesn't need to actually focus on anything after you focus on the nearest point. I am assuming the camera simply moves the focus in the STEP amount each time... no need to focus on anything after the foreground focus point is set.
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I might be wrong but my camera is set to manual focus so I am assuming Focus Bracketing works in MF. It doesn't need to actually focus on anything after you focus on the nearest point. I am assuming the camera simply moves the focus in the STEP amount each time... no need to focus on anything after the foreground focus point is set.
Thank you! I didn't know this.
I just tested it and it works, including with the focus clutch lenses (specifically the 16 F1.4 that I had already mounted).
It basically makes no sense not to use MF for focus stacking, particularly if you use the tripod.
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But you still have to focus on the near point - either manually or AF. I use the quick-AF button and position the little focus rectangle box on the point I want focused. But I never have AF turned on. The quick AF focus button is a handy feature.
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I’m using manual focus with Focus Bracketing. I’ve learned to focus on my starting point, and then rack the lens a tiny bit “closer” so that the sequence starts its focus run just in front of the desired “start point.” I get better overall results that way.
Rand
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If your using close focus stacking 25 mm total and your secured to bedrock you will get vibration but if your focus stacking 1meter you might not see it.
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Won’t ES reduce the vibration?
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Won’t ES reduce the vibration?
I use ES when focus stacking macro static subjects. There is zero vibration. At that point the only source of vibration is the lens’ incremental focus movements. You can hear a light “focus motor buzz” between shots. So, I can set the interval to several seconds if I think the lens movement might be inducing any vibration into the system.
Rand
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Thanks, Rand!