Luminous Landscape Forum

The Art of Photography => Discussing Photographic Styles => Topic started by: JohnKoerner on September 15, 2011, 01:28:46 pm

Title: Focus Stacking versus HDR?
Post by: JohnKoerner on September 15, 2011, 01:28:46 pm
Is there a difference between focus stacking macro shots and making HDR landscape images?

I see all of the hooplah about HDR, but I am wondering what people's thoughts are on "stacking" macro images to get a greater depth-of-field.

One of the great problems with macro photography is the fact that with wide apertures that produce "pleasing bokehs," you get a very shallow DOF, and with narrow apertures that give great DOF you run into problems of diffraction (not to mention lousy bokehs).

Well, focus-stacking macro images using a wide aperture gives a macro shooter the best of all possible worlds: namely razor-sharp images with great depth-of-field, no more worrying about diffraction, as well as the ability to maintain a pleasing bokeh. In fact, scientifically, now virtually ALL microscopic subjects are focus-stacked with sometimes hundreds of images compiled together into one image by both special remote stacking devices (as well as software) these days ... which was something that was IMPOSSIBLE to do with film photography. This has enabled the production of nearly 3-D images of germs and such that were impossible to see cohesively previously.

In other words, focus-stacking is considered great and critically-important to macro photography and photomacrography ... and yet most "art" photographers seem to hate HDR in landscape images. I was just curious, but isn't focus-stacking a macro shot essentially the same thing as creating an "HDR" image in landscape photography? (Or am I misunderstanding something?)

Jack



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Title: Re: Focus Stacking versus HDR?
Post by: hjulenissen on September 15, 2011, 01:35:46 pm
...isn't focus-stacking a macro shot essentially the same thing as creating an "HDR" image in landscape photography? (Or am I misunderstanding something?)
HDR is about increasing the effective Dynamic range: making details visible in both dark shades and in bright highlights.

Focus stacking is about increasing the effective DOF: making details sharp both close to the camera and far from it.

-h
Title: Re: Focus Stacking versus HDR?
Post by: Bart_van_der_Wolf on September 15, 2011, 01:49:50 pm
In other words, focus-stacking is considered great and critically-important to macro photography and photomacrography ... and yet most "art" photographers seem to hate HDR in landscape images.

They don't hate HDR photography, they 'hate' the subsequent surreal tonemapping.

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I was just curious, but isn't focus-stacking a macro shot essentially the same thing as creating an "HDR" image in landscape photography? (Or am I misunderstanding something?)

The only similarity is in using multiple images per frame.

HDR photography attempts to capture a huge dynamic range, which exceeds the capability of most cameras capturing such a scene in a single shot. Exposure bracketing is used to collect the correct exposure for various luminance levels.

Focus bracketing uses a series of images that are focused at different parts of the image (with approx. the same exposure settings), and combines the sharpest parts of each image to composite an image that has deeper DOF than single exposures can. These exposures are taken with a relatively wide aperture where diffraction doesn't degrade image quality as much as with narrow apertures.

So one uses exposure, the other uses focus. Seems quite different to me ...

Cheers,
Bart 
Title: Re: Focus Stacking versus HDR?
Post by: JohnKoerner on September 15, 2011, 02:07:09 pm
Okay, thanks for explaining the difference to me.

Jack


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Title: Re: Focus Stacking versus HDR?
Post by: RFPhotography on September 15, 2011, 04:02:23 pm
They're similar in that they both use combinations of multiple images to achieve and end result.  But aside from that, not a lot in common.
Title: Re: Focus Stacking versus HDR?
Post by: wolfnowl on September 16, 2011, 01:48:57 am
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They don't hate HDR photography, they 'hate' the subsequent surreal tonemapping.

Took the words right out of my mouth.  I know Vincent Versace took to calling his high dynamic range image 'XDR' for extended dynamic range rather than HDR because of the common confusion over this.  There's a good article on this site on this: http://www.luminous-landscape.com/essays/hdr-plea.shtml

And these are HDR images:

(http://farm6.static.flickr.com/5002/5358262192_2319ce9c04_o.jpg)

(http://farm6.static.flickr.com/5219/5385249064_974448b878_o.jpg)

(http://farm6.static.flickr.com/5089/5269777411_330ac2ec51_o.jpg)

(http://farm6.static.flickr.com/5256/5512545307_b7668dd2ef_o.jpg)

Mike.

Title: Re: Focus Stacking versus HDR?
Post by: PeterAit on September 16, 2011, 09:38:11 am
They are completely different techniques. HDR takes multiple images of the same scene, same focus, with different exposure settings. For example, the less-exposed image will get the highlights right while blocking the shadows, and the more-exposed image will get the shadow detail right while blowing the highlights. Software then melds the "properly" exposed portions of the two (or more) images.

A lot of HDR images just look fake, they scream "HDR" at you.
Title: Re: Focus Stacking versus HDR?
Post by: RSL on September 16, 2011, 10:43:52 am
A lot of HDR images just look fake, they scream "HDR" at you.

Peter, As several people, most recently Mike, have pointed out, HDR isn't the problem. The problem is the tonemapping. Some post-processors seem to go out of their way to tonemap their results into scratchy, unreal images that give the idea HDR can't produce a normal picture. Others use HDR simply to bring impossible dynamic ranges under control. In the latter case, unless you know what to look for, you'll never know the picture was made with HDR techniques. Here are two examples of what are at least attempts to take the second approach.
Title: Re: Focus Stacking versus HDR?
Post by: Slobodan Blagojevic on September 16, 2011, 11:52:35 am
Jack,

Let me try to explain the type of HDR most of us "hate" in terms that you can relate to, i.e., in terms of focus-stacking.

You use focus-stacking selectively (and rightly so): you bring the main object into sharp focus, while keeping the background nicely blurred. The best of both worlds, indeed.

Now, imagine you do not stop with focus-stacking when you have the main object sharp, but continue focus-stacking all the way to infinity, rendering absolutely everything along the way tack-sharp. Do I hear you say: eeeewww!? You do not want the background sharpness to interfere with the main object, you'd say, it defies the purpose!

And that is why we "hate" some HDR: it brings attention to every tone, every detail, every shadow and every highlight... everything becomes visible and everything appears important.
Title: Re: Focus Stacking versus HDR?
Post by: hjulenissen on September 16, 2011, 01:50:40 pm
Now, imagine you do not stop with focus-stacking when you have the main object sharp, but continue focus-stacking all the way to infinity, rendering absolutely everything along the way tack-sharp. Do I hear you say: eeeewww!? You do not want the background sharpness to interfere with the main object, you'd say, it defies the purpose!
I thought this was the holy grail of landscape photography? :-)

-h
Title: Re: Focus Stacking versus HDR?
Post by: Slobodan Blagojevic on September 16, 2011, 02:08:02 pm
I thought this was the holy grail of landscape photography? :-)

Ah, but you forgot that we are talking here about macro or close-up photography, not landscape.
Title: Re: Focus Stacking versus HDR?
Post by: fdisilvestro on September 16, 2011, 02:13:43 pm
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focus-stacking... ... which was something that was IMPOSSIBLE to do with film photography

Not really impossible:  Scanning light photography (http://kazilek.com/pages/slp.htm)

Title: Re: Focus Stacking versus HDR?
Post by: JohnKoerner on September 16, 2011, 02:22:06 pm
Not really impossible:  Scanning light photography (http://kazilek.com/pages/slp.htm)


Very interesting, thanks for sharing :)
Title: Re: Focus Stacking versus HDR?
Post by: JohnKoerner on September 16, 2011, 02:32:15 pm
They are completely different techniques. HDR takes multiple images of the same scene, same focus, with different exposure settings. For example, the less-exposed image will get the highlights right while blocking the shadows, and the more-exposed image will get the shadow detail right while blowing the highlights. Software then melds the "properly" exposed portions of the two (or more) images.
A lot of HDR images just look fake, they scream "HDR" at you.

Well, the term "fake" is pejorative.

I prefer the term "surreal" :D

I have seen some HDR images that indeed do look "surreal" to me, but yet I still thought were nice images. Case in point, one member here (I forget his name) posted a photo of some cows and a barn last year ... that was a HDR image (and indeed looked "surreal") ... but I thought it was cool and actually found it much more interesting than had the image been rendered traditionally.

So, to me, I guess it would depend on the subject ... but I can definitely see why some people might be attracted to trying this technique ... both for attempting to gather legitimate DR beyond their camera's capability (and yet still look "natural") as well as to deliberately create surrealism.

I personally don't think there is anything wrong with either approach.

Jack


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Title: Re: Focus Stacking versus HDR?
Post by: JohnKoerner on September 16, 2011, 03:00:38 pm
Jack,
Let me try to explain the type of HDR most of us "hate" in terms that you can relate to, i.e., in terms of focus-stacking.
You use focus-stacking selectively (and rightly so): you bring the main object into sharp focus, while keeping the background nicely blurred. The best of both worlds, indeed.

Agreed.




Now, imagine you do not stop with focus-stacking when you have the main object sharp, but continue focus-stacking all the way to infinity, rendering absolutely everything along the way tack-sharp. Do I hear you say: eeeewww!? You do not want the background sharpness to interfere with the main object, you'd say, it defies the purpose!
And that is why we "hate" some HDR: it brings attention to every tone, every detail, every shadow and every highlight... everything becomes visible and everything appears important.

I personally would consider such an extensive focus-stacking effort a waste of time, as pretty much only my subject is of interest to me, unless there were some elements of the back/fore-ground that I likewise felt were important to add to the composition. So I do understand your point: why spend so much time "detailing" elements of a composition that don't matter at all?

For this reason, in most cases I would consider all the extra effort at producing a HDR image to be a neurotic obsessive/compulsive disorder on the part of the photographer (LOL), because it seems like an incredible pain the ass to process images in this way (http://www.johnkoerner.org/Emoticons/lol.gif)

And yet I also think some people might just be turned on to "the surreal effect" of HDR imaging, whether or not any of the highlighted details are actually "important" to the composition or not. In other words, it seems to me that some people are merely turned-on by the overall HDR "feel" more so than anything inherently valuable being detailed so extensively. So, even though I personally wouldn't waste my time doing this, I don't see anything to "hate" in it either. It's a simple matter of different strokes for different folks, and I have to admit that I sometimes think the effect is kinda cool too :)

However, HDR efforts outlined by Mike (Wolfnowl) as well as by the posted article by Alexandre Buisse make the most sense to me: trying to capture all the potenial range of a wonderful image that "one click at one exposure setting" can't possibly capture. With certain scenes, I can definitely see the value in making this kind of photographic (and post-processing) effort, for essentially the same reasons as I focus-stack my macro shots, but they just do it for tones and colors too.

So I agree most images are simply not worth the effort ... same as I don't bother trying to focus-stack every macro shot I see either ... but if it floats some people's boats to do it with otherwise mundane subjects, it's their time to waste doing it (http://www.johnkoerner.org/Emoticons/laugh.gif)

Jack


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Title: Re: Focus Stacking versus HDR?
Post by: Guillermo Luijk on September 16, 2011, 03:52:30 pm
They are completely different techniques. HDR takes multiple images of the same scene, same focus, with different exposure settings. For example, the less-exposed image will get the highlights right while blocking the shadows, and the more-exposed image will get the shadow detail right while blowing the highlights. Software then melds the "properly" exposed portions of the two (or more) images.

Completely different techniques? let's see:

HDR: take different shots at different exposure values
FS: take different shots at different focus distances

HDR: blend them taking the areas with highest exposure as long as they are not clipped
FS: blend them taking the areas with highest local contrast

HDR needs the additional step to match exposure in all the source areas, and tone map the resulting blend to produce an output image. But the concept remains the same: several captures to take the best parts from the best source candidates.

Regards

Title: Re: Focus Stacking versus HDR?
Post by: JohnKoerner on September 16, 2011, 06:51:20 pm
That is what I perceived too, is that there are more similarities than dissimilarities.

While I recognize the difference, in each case there is still an effort to get "more" out of an image (through the combining of multiple images) than what is now possible from just a single capture. Some of the reasons/technical aspects may be different, but the main concept behind each effort is the same: combine multiple images into "one" image that would not be possible with current technology.

Jack



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Title: Re: Focus Stacking versus HDR?
Post by: PeterAit on September 17, 2011, 09:48:26 am
Oh, I agree completely and did not mean to imply that there's something wrong with HDR per se.
Title: Re: Focus Stacking versus HDR?
Post by: Justan on September 17, 2011, 02:22:08 pm
> Is there a difference between focus stacking macro shots and making HDR landscape images?

Yes.

Here’s a member who's a master of the art forms (http://www.luminous-landscape.com/forum/index.php?topic=54698.0) and who does both, *and* integrates them into panos. In this example he provides a detailed and illustrated example.


Title: Re: Focus Stacking versus HDR?
Post by: JohnKoerner on September 19, 2011, 07:05:37 am
> Is there a difference between focus stacking macro shots and making HDR landscape images?
Yes.
Here’s a member who's a master of the art forms (http://www.luminous-landscape.com/forum/index.php?topic=54698.0) and who does both, *and* integrates them into panos. In this example he provides a detailed and illustrated example.


Interesting, thanks Justan.

The most interesting detail about that thread, at least to me, was that Bill's opinion on focus-stacking software proved to be exactly the opposite of my own (http://johnkoerner.org/Blog/2011/08/09/focus-stacking-software-revisited). I found that Helicon was nowhere near as effective as Adobe CS5.

Jack

PS: You were right on that other thread too: one slight breeze can create hours of post-processing "stacking work" (http://www.johnkoerner.org/Emoticons/laugh.gif)


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Title: Re: Focus Stacking versus HDR?
Post by: Bart_van_der_Wolf on September 19, 2011, 10:13:21 am
I found that Helicon was nowhere near as effective as Adobe CS5.

Hi Jack,

I noticed that you didn't use Helicon Focus' 'method B' (similar in segmentation approach to Zerene Stacker's Pmax mode). I have to assume that you chose the optimal parameters for the 'Method A' you apparently used, i.e. you didn't mention which settings for radius and smoothing gave the best results so perhaps you just used defaults?
Likewise, Zerene Stacker offers parameters to improve the results depending on the stack 'quality' (amount of DOF overlap).

Your results are interesting, in that an earlier test I did between Photoshop (CS4?) and Helicon Focus Pro turned out less favorable for Photoshop. Perhaps the different Photoshop versions give different results, and CS5 has improved.

And while I agree that it's desirable for the initial output to be close to ideal, it is also important if and how the (inevitable) artifacts can be retouched most successfully. Photoshop doesn't offer much in that respect.

Cheers,
Bart
Title: Re: Focus Stacking versus HDR?
Post by: JohnKoerner on September 19, 2011, 10:31:16 am
Hi Jack,
I noticed that you didn't use Helicon Focus' 'method B' (similar in segmentation approach to Zerene Stacker's Pmax mode). I have to assume that you chose the optimal parameters for the 'Method A' you apparently used, i.e. you didn't mention which settings for radius and smoothing gave the best results so perhaps you just used defaults?
Likewise, Zerene Stacker offers parameters to improve the results depending on the stack 'quality' (amount of DOF overlap).
Your results are interesting, in that an earlier test I did between Photoshop (CS4?) and Helicon Focus Pro turned out less favorable for Photoshop. Perhaps the different Photoshop versions give different results, and CS5 has improved.
And while I agree that it's desirable for the initial output to be close to ideal, it is also important if and how the (inevitable) artifacts can be retouched most successfully. Photoshop doesn't offer much in that respect.
Cheers,
Bart


Hi Bart;

You are correct that I used the Helicon default.

I don't know if there is a difference between CS4 and CS5, but the CS5 worked best for me by a pretty wide margin (especially in maintaining the quality of the bokeh). Regadring dealing with artifacts, I have found Photoshop's heal, clone, and lasso tools to be excellent in this respect.

If we call the composite stack the "Master" file, and if we call the individual files that were used to create it the "donor" files, I have found that using either the Heal/Clone/Lasso tools on the best donor file of that created that part of the Master image, and applying the tool to the area of the Master file that needs work, works wonderfully.

Jack


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Title: Re: Focus Stacking versus HDR?
Post by: Monito on September 28, 2011, 07:04:43 pm
Mechanically, there may be similarities between focus stacking and HDR.  However, in terms of art, they are worlds apart.

It's rather like saying that because landscape and sports photography both use shutters they are very similar.  The opposite is true.  They are very different in spite of both using shutters.

As stated above, the key to good HDR is good tonemapping when compressing the range.