Focus Stacking

[Mike Sellers]

Do you get a noticeable increase in focus when using this method? Under what condition do you tend to use it?

[torger]

The "traditional" use case for focus stacking is macro photography, and today I think most jewelry/watch/etc photographers use stacking extensively. In those cases the stacks can be of several tens of shots, say 20-40 shots as the depth of field is ultra-short in macro photography. Many jewelry shots we see today aren't possible to do without stacking.

However focus stacking has become popular in landscape photography as well, and there the technique seem to differ between photographers. Usually the full focus range close to far in a landscape (non-macro) shot can be covered in say 5-8 shots, but rather than shooting all those shots as you would in a studio macro setup most make one shot focused on an important foreground object, and then another shot focused at an important background object, so you have two shots which does not really give equal sharpness throughout the scene but you have high sharpness where it counts. If you pixel peep and have a continuous scene you see that it goes a bit soft midway, and then turns sharp again for the far shot.

As I mentioned in a different thread I don't use it myself although I have experimented with it a bit to see how it works, both in macro and in landscape applications. For my own work I prefer to "compromise" with tilt/swing and smaller f-stops and do it in one shot.

The scenes I've seen other landscape photographers do with stacking is typically one with a very close subject like a group of flowers (camera is low, close to the flowers) or a close tree trunk with visible bark structure, and then a background that stretches into infinity. Often the midway is either not visible or without much features so that it's less sharp on the middle doesn't really matter.

When you google for stacked landscape images many compositions are "gimmicky" with ultra-close foreground, but among tech cam users it's quite common to shoot pretty normal compositions which you could shoot with say f/22 but you stack to make it with f/11 to gain more resolution.

One problem I discovered with stacking for landscape is that since you have focus breathing the stacker needs to scale at least one image slightly to fit together, and if you have a very sharp f/11 shot with jagged lines (which you get with tech lenses) the slight scaling doesn't look that good on pixel peep level, and then I rather step up to f/16 or even f/22 to make the scaling look good, and when you've done that you already have pretty deep depth of field, especially if combined with tilt. So I haven't found much value in it personally.

[torger]

Attached is one of my recent shots that could have gained from stacking. I couldn't really use swing here to get the close fence in focus because that would pull the leftmost tree out of focus. I'd probably do one close f/22 that would overlap with one hyperfocal f/16. The resolution junkies would probably do more shots and combine f/16 with f/11.

However, as I like the one-shot-photograph I satisfied with one single f/20-22 shot here (don't remember the exact f-stop) and let the close fence be a tiny bit out of focus, as it's no fine details there I thought it was okay.

[Wayne Fox]

Do you get a noticeable increase in focus when using this method? Under what condition do you tend to use it?

  I use focus stacking when the scene is pretty stationary and I need more depth of field than the lens can deliver.  Sometimes I could get more depth of field by stopping down, but would prefer to stay in the lens sweet spot of f/8 or 11 which requires focus stacking.

My technique is little different than most, I only focus once on the near point.  I then shoot a series, moving focus towards infinity until I reach that point.  Sometimes only 3 shots, sometimes more. Infinity isn’t always required for the shot, but I know once I get there I’ve got everything in focus. Here’s a shot which is a focus stack of 9 captures.

[pfigen]

I use focus stacking all the time for product photos, especially where I want a sort of hyper realism and where lens and/or camera movements won't do the trick, and even stopping down all the way won't come close to full, deep focus. I generally use Helicon Focus, but sometimes I just blend the images manually in Ps. Whatever provides the best outcome.

The first image from Honeywell Aerospace is 37 slices with a Canon 24mm t/s-e. The second is 29 slices with a Canon 17mm t/s-e on a 5DSR, and the third one of the Garrett turbocharger is ten slices shot on 4x5 T-Max and manually brushed together. Even shooting that at f/22-1/2 was not nearly enough and only provided enough overlap to actually have a successful blend.

I use focus stacking for all kinds of images from product to architectural interiors to landscape, but not really for people.

[MattBurt]

  I use focus stacking when the scene is pretty stationary and I need more depth of field than the lens can deliver.  Sometimes I could get more depth of field by stopping down, but would prefer to stay in the lens sweet spot of f/8 or 11 which requires focus stacking.

My technique is little different than most, I only focus once on the near point.  I then shoot a series, moving focus towards infinity until I reach that point.  Sometimes only 3 shots, sometimes more. Infinity isn’t always required for the shot, but I know once I get there I’ve got everything in focus. Here’s a shot which is a focus stack of 9 captures.

That's an interesting shot and I think the stacking gives it a hyper-real look. What software did you use to stack?

[Mike Sellers]

The reason I brought this up is I was contemplating buying a Rollei Hy6 and it has a autofocus function that can shoot up to 9 images and I thought this would be a very interesting feature.
Mike

[Phil Indeblanc]

make sure you know how you will achieve the next focus. I don't know how the Hy6 does this, but the point is to keep the lens stationary.

[Wayne Fox]

That's an interesting shot and I think the stacking gives it a hyper-real look. What software did you use to stack?

Not sure what you mean by hyper real.  Looks pretty much like the 2 shots or so taken in the middle of the series except foreground and background are sharp.

I used Helicon Focus for this stack.  Sometimes PS does an OK job.

[MattBurt]

Not sure what you mean by hyper real.  Looks pretty much like the 2 shots or so taken in the middle of the series except foreground and background are sharp.

I used Helicon Focus for this stack.  Sometimes PS does an OK job.

It's hard to put my finger on it but maybe it's the close sharp foreground combined with the very sharp background not being something I'm used to seeing in a photo. It just has a different look than what my brain expects or something.

[Bart_van_der_Wolf]

It's hard to put my finger on it but maybe it's the close sharp foreground combined with the very sharp background not being something I'm used to seeing in a photo. It just has a different look than what my brain expects or something.

Hi Matt,

Yes, it adds a sense of hyper-realism, probably because we subconsciously need to (re-)focus our eyes at several distances to mentally composite the whole scene in focus. With a focus stacked image we see everything in focus , at the same eye-focus distance (the picture).

Cheers,
Bart

[Chris Livsey]

Hi Matt,
Yes, it adds a sense of hyper-realism, probably because we subconsciously need to (re-)focus our eyes at several distances to mentally composite the whole scene in focus.
Cheers,
Bart

Yet the effect, and I see it/experience it, doesn't seem to be there with the "product" shots?

[pfigen]

I actually think the hyper realistic feeling comes from the fact that we're not used to seeing 2D photos with infinite focus, particularly when there is some part of the subject matter close to the camera. Most of the time when we look at a scene with our own eyes, we perceive the entire scene to be in focus - automatically. Unless something is too close to your eye to focus, we really don't tend to see with selective focus. I love doing this for product photography because clients aren't used to seeing their products this way. And they do love it. It's not practical to shoot everything with infinite focus, but the ones I do certainly stand out. I did a shot today of a medical testing product that was fifty-nine slices with the new Canon 35L on a 5DSR. Quite a remarkable combination.

[torger]

There's two distinct reasons here. One is the "macro" use case, where parts of an image is clearly out of focus regardless which f-stop you'll be using. The product photography demonstrated in this thread is not really macro but still at a scale that makes focus-stacking necessary to avoid a clear out-of-focus blur.

Then we have the grand scene landscape use case where it's more about not wanting to stop down to f/16 as you get sharper pixels at f/8, but still you want the DoF of f/16 (or a bit more). This use case is a result of very high resolution cameras so we get the same DoF challenge that was always there for large format film. Stacking is often used as an alternative to tilt on SLRs cameras without movement capability, but you can also use it in scenes that you can't really focus with tilt/swing, like the examples earlier in this thread.

While I do see the value of stacking in the "macro" use case, I remain mildly skeptical about this second use case. I just get a feel that we're just pushing a bit too hard for more resolution. If you get medium format for the sole reason of getting more resolution it's a natural direction to go though...

I repeat also my skepticism about the second use case as I think there's more to pixel peep image quality than high pixel-to-pixel micro contrast. With 5-6um pixels without AA-filter an f/8 shot becomes aliased. Slight rescalings of aliased images becomes even more aliased (focus stacking requires rescaling to compensate focus breathing). To me it's more important to avoid ugly aliasing at the pixel peep level than maximize micro contrast. If you agree with me on that you'll find that the grand landscape stacking case is very narrow indeed. There's also almost impossible to avoid at least some stack merge artifact somewhere in the picture, and again you need to decide where to put your perfectionism, higher pixel micro contrast, or total lack of merging artifacts?

[pfigen]

"There's also almost impossible to avoid at least some stack merge artifact somewhere in the picture, and again you need to decide where to put your perfectionism, higher pixel micro contrast, or total lack of merging artifacts?"

Torger - sure, there are often artifacts, but that's why we have Photoshop. Prior to these tools, the options were very limited and we just put up with some pretty crappy images. The bottom line is that we now have options to realize our vision. If it's not your vision, then don't focus stack. It's just another tool for me that gets used when it's appropriate. I am so happy to have these new modern tools. Hell, I remember trying to get full deep focus depth of field thirty years ago, and it was just not possible, especially on products. I  also remember pulling the aperture ring all the way over on a Symmar S - way past the last marked f/stop. Probably somewhere between f/90 and f/128, and you could see with your bare eyes how soft that 4x5 transparency was. You can only do so much with swings and tilts and even less with the same movements from a Canon or a Nikon, plus a severe tilt or swing is no free lunch. Lots of off axis wonderment. Then, far before there was an Align Layers command or a Helicon Focus to make thing easier, I was doing much cruder focus stack, where I would blend two focus slices and have to manually use Free Transform to accommodate the breathing. More complicated and more time consuming but it still worked. You just have to ask yourself if your image is better off or not for having used any of these techniques. I use them because I think they make those images better.

[Ken R]

Awesome application of focus stacking on those product shots!

On Landscape I can see many instances where it would be useful. Although I personally prefer single shot and choosing the focus point is part of the creative process and I enjoy having that limitation and having to make that choice. Quite a few times landscape images that have a lot of focus stacking look a bit off or odd and unnatural.

Generally if a landscape composition has a prominent and interesting foreground it is best to focus there and let the focus fade naturally into the background if tilt is not available.

[kers]

i like focus stacking for landscapes...
this image was made of about 500 shots with a D810.
it is a 360 panorama of the new train station in Arnhem- the Netherlands

a 100% version can be viewed here (also full screen) :   

http://www.beeld.nu/sa.html

[Peter McLennan]

I frequently focus stack landscapes.  This one was made with a 28mm Nikkor.  Nine images, hand blended in Photoshop. 
The foreground sand grains are less than a metre from the lens.  Eureka Dunes.

[BernardLanguillier]

I have been using this technique for nearly 10 years now.

Two examples shot last week combining stitching and DoF stacking:





Both were captured with the Otus 55mm f1.4 on the D810.

Cheers,
Bernard

[Stephen Girimont]

Bernard (or anyone else), could you elaborate on your process at the camera and in post when combining stitching and focus stacking? I haven't yet experimented with the combination, but I've been thinking about it.