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Author Topic: FOCUS STACKING with a VIDEO SLIDER  (Read 663 times)
Michael Erlewine
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« on: May 13, 2014, 09:41:43 AM »
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I have been doing close-up and macro photography since 1956, so I guess that dates me. Since the advent of digital photography and the various Nikon systems I have been using them. And over the last many years I have been experimenting with stacking focus. As many of you know, this can be a relatively elaborate procedure and I have written two books on the subject, many articles, and some 22 or so videos on the topic, all free.

Books and Articles Here:

http://dharmagrooves.com/e-Books.aspx#Photography

Videos Here:

https://www.youtube.com/playlist?list=PL5xDr8mWUwrzi4bxY978O1DQykUrj-S2I

I am not a professional photographer, of my own choosing. To me the process of photography has been a passion, and sometimes the results are OK too.

I have also been into digital video for many years, but more as a dabbler than anything else. I had a Panasonic HVX-200 early on and followed the advent of DSLR video as it came along, but was never too thrilled about the results.

Instead I stayed with still photography, and my interest with that increased with the Nikon D3x and 24 MP, and most certainly with the Nikon D800e, and getting rid of the AA filter. That was a huge step for me because those 36 MP and the increased clarity possible made focus stacking much more rewarding.

And it was never lost on me that the whole process of focus stacking could be done several ways, and some of them had better results than others. I was an early adopter of Zerene Stacker software, and learned a lot from its designer Rik Littlefield, including the best way to reduce artifacts when stacking photos to make it easier on the stacking software. Here are the main three I am aware of. I will start with the worst and move to the best.

According to Littlefield, the method most prone to creating artifacts in your finished stacked photo is mounting your lens and camera on a focus rail and then moving camera and lens forward along the rail, shot by shot.

The second best method is just turning the heliocoid (focus ring) on your lens and stepping through a series of layered focus, taking photos as you go.

And the very best method is to mount the lens on one end of a bellows and the camera on the other end and then only move the back-standard forward to focus. Of course, this is difficult for many lenses, although some few lenses (Nikon 35mm f/1.4G) have back-focus built in).

True to form, I have of course tried all three methods for focus stacking, taking over the years many hundreds of thousands of photos in the process. As I pointed out, the process is what I like, even more than the results.

And it did not escape me some years ago that another approach to the very tedious process of focus stacking would be to have a video camera in focus on the front of a subject and just slide it forward while recording in some form of progressive-frame codec. Then, take the video, export each frame as a .TIFF, and process it as you would any other layered focus stack.

In fact I had Krysztof Hejnar at Hejnar Photos build me a custom focus rail that, instead of being a geared rail, was just a very smooth slide. I then mounted my cameras via an Arca Swiss clamp on the video rail, started recording, and just gently slide the whole camera forward, toward the subject. Below is the video slider built by Hennar, top and bottom.

The result was a stacked series of layers, accumulated much more smoothly than I could ever have done it by hand. And it worked. The only problem is that the frame size of something like 1920x1080 was just too small a photo for really fine focus stacking.

With 4K video now available (and perhaps larger formats threatening), it is time to revisit this technique, using the larger 4K format (3840x2160) and its increased frame size.

There is no reason this would not work with a focus rail by turning the helicoid on the lens, on a focus rail, or by mounting the lens and camera on opposite ends of a bellows and moving the rear standard on the bellows. And it does.

I include here a stacked result of a series of TIFF files from a 4K (3840x2160) clip taken on the new Lumix GH4 camera. It was then loaded into Premiere Pro CC, and the frames were exported as TIFF files, which were then fed into Zerene Stacker. The resulting stacked photo was loaded into Adobe Lightroom and tweaked, etc.

I was shooting here with the Zeiss Sonnar 135mm f/2 APO lens, an exquisite lens. I would never call the resulting photo a "keeper" (a good example of a stacked photo), but it does show that for those interested, it is possible to (in a second or so) to quickly produced a stacked photo which otherwise would take a much longer time to create.

I am too busy just now shooting a documentary film to take time to refine this procedure, but some of you may want to play with it, so I put the idea out there.

My guess is the 4K could, with finessing, produce some fairly decent video stacks. However, a 6K or 8K video stream would be much better. It is clear that sometime in the future this technique could be usefully implemented.

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Michael Erlewine
Founder: MacroStop.com, AMG - All-Movie Guide, All-Music Guide, All-Game Guide, Matrix Software, Classic Posters, ClassicPosters.com, SpiritGrooves.net, and other sites.
BartvanderWolf
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« Reply #1 on: May 14, 2014, 06:02:26 AM »
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I have been doing close-up and macro photography since 1956, so I guess that dates me. Since the advent of digital photography and the various Nikon systems I have been using them. And over the last many years I have been experimenting with stacking focus. As many of you know, this can be a relatively elaborate procedure and I have written two books on the subject, many articles, and some 22 or so videos on the topic, all free.

Books and Articles Here:

http://dharmagrooves.com/e-Books.aspx#Photography

Videos Here:

https://www.youtube.com/playlist?list=PL5xDr8mWUwrzi4bxY978O1DQykUrj-S2I

Hi Michael,

Thank you for your great contributions. I like your focus stacks very much, and I know from experience how much effort it takes to take good source images.

Quote
And it was never lost on me that the whole process of focus stacking could be done several ways, and some of them had better results than others. I was an early adopter of Zerene Stacker software, and learned a lot from its designer Rik Littlefield, including the best way to reduce artifacts when stacking photos to make it easier on the stacking software. Here are the main three I am aware of. I will start with the worst and move to the best.

According to Littlefield, the method most prone to creating artifacts in your finished stacked photo is mounting your lens and camera on a focus rail and then moving camera and lens forward along the rail, shot by shot.

The second best method is just turning the heliocoid (focus ring) on your lens and stepping through a series of layered focus, taking photos as you go.

And the very best method is to mount the lens on one end of a bellows and the camera on the other end and then only move the back-standard forward to focus. Of course, this is difficult for many lenses, although some few lenses (Nikon 35mm f/1.4G) have back-focus built in).

True in general, although it also depends on the size of your subjects. Rik Littlefield has an instructive page on the focus versus rail trade-off. Basically, anything larger than a raisin is preferably shot with the focus ring rather than a focus rail, and a rear bellows adjustment is generally better.

It also depends a bit on the subject matter though, because objects without occlusions can be shot quite well with a focus rail (natural perspective does change more than with ring focusing), especially when it is an automated one which can save a lot of time. Also, not all manual focus lenses have a useful long focus throw (which e.g. the Zeiss Otus 55mm does have) which is very handy for precise focusing by hand, so a rail could help to get predictable results in those cases.  

Quote
True to form, I have of course tried all three methods for focus stacking, taking over the years many hundreds of thousands of photos in the process. As I pointed out, the process is what I like, even more than the results.

And it did not escape me some years ago that another approach to the very tedious process of focus stacking would be to have a video camera in focus on the front of a subject and just slide it forward while recording in some form of progressive-frame codec. Then, take the video, export each frame as a .TIFF, and process it as you would any other layered focus stack.

Yes, that will work if the rail moves smooth enough to avoid camera vibration. The frame rate is high enough (useful with moving insects) to allow a quick capture of a full set of distances. I remember a stacked shot I tried to make of a dead bumblebee. The finished result showed a strange yellow line across the body of the insect which, upon closer inspection, was a mite walking around on the bumblebee through the consecutive frames ...

Quote
In fact I had Krysztof Hejnar at Hejnar Photos build me a custom focus rail that, instead of being a geared rail, was just a very smooth slide. I then mounted my cameras via an Arca Swiss clamp on the video rail, started recording, and just gently slide the whole camera forward, toward the subject. Below is the video slider built by Hennar, top and bottom.

How do you determine the speed to travel at? Is is vibration or motion blur based, or did you look at the amount of focus overlap? To cover a stack from 100mm to 500mm distance, with a 55mm lens at f/5.6, would require 518 frames on my 6.4 micron pitch camera, or some 21 seconds at 25 frames / sec. On a Panasonic GH4 in HD video mode that would be 277 frames, or some 11 seconds at 25 f/s, or 551 frames @ 25 f/s is 22 seconds on 4K video mode. Is that about the speed you use, or do you go faster/slower on the rail?

Quote
The result was a stacked series of layers, accumulated much more smoothly than I could ever have done it by hand. And it worked. The only problem is that the frame size of something like 1920x1080 was just too small a photo for really fine focus stacking.

With 4K video now available (and perhaps larger formats threatening), it is time to revisit this technique, using the larger 4K format (3840x2160) and its increased frame size.

Indeed, at 4K it becomes an interesting technique to consider.

Quote
I include here a stacked result of a series of TIFF files from a 4K (3840x2160) clip taken on the new Lumix GH4 camera. It was then loaded into Premiere Pro CC, and the frames were exported as TIFF files, which were then fed into Zerene Stacker. The resulting stacked photo was loaded into Adobe Lightroom and tweaked, etc.

Look quite usable on a webpage size. How many frames did that take?

Quote
I was shooting here with the Zeiss Sonnar 135mm f/2 APO lens, an exquisite lens. I would never call the resulting photo a "keeper" (a good example of a stacked photo), but it does show that for those interested, it is possible to (in a second or so) to quickly produced a stacked photo which otherwise would take a much longer time to create.

I am too busy just now shooting a documentary film to take time to refine this procedure, but some of you may want to play with it, so I put the idea out there.

My guess is the 4K could, with finessing, produce some fairly decent video stacks. However, a 6K or 8K video stream would be much better. It is clear that sometime in the future this technique could be usefully implemented.

I agree, it's always a good thing to keep an open mind for new possibilities as technology unfolds the opportunities.

Cheers,
Bart
« Last Edit: May 14, 2014, 06:09:21 AM by BartvanderWolf » Logged
Michael Erlewine
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« Reply #2 on: May 15, 2014, 02:33:58 AM »
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Thanks for the note. Yes, I have seen that instruction page by Littlefield who, in my opinion, is a real genius at this technique.

"Bug walking" is a constant in outdoor macro work. I am frequently surprised to find all kinds of other critter cameos in the finished stack, bugs I never knew were there, including one-time an assassin bug I never saw who was waiting to grab the bug I was photographing.

As far as speed of travel, it does not seem to matter much, just smoothly if possible. It is also works to attach one of those "jar openers" to the lens and turn the focus ring smoothly.  The image shown, which is poor, was perhaps 250 or so layers.

I shoot mostly by focus ring, secondly by bellows, and lastly by rail, although I like to use a rail a lot…. but the results produce more artifacts, of course.

Yesterday, I packed up and am shipping off about 8K worth of macro lenses I will never use, selling them on Amazon. I don't want a museum. I want the best lenses I can afford. I sold my Nikon 200mm Macro, my Nikon Zoom Macro 70-180, and a lot of others. I never…. ever… use them anymore.
« Last Edit: May 15, 2014, 02:35:49 AM by Michael Erlewine » Logged

Michael Erlewine
Founder: MacroStop.com, AMG - All-Movie Guide, All-Music Guide, All-Game Guide, Matrix Software, Classic Posters, ClassicPosters.com, SpiritGrooves.net, and other sites.
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