Jump to content
Michael Erlewine

Stacking: Caught between the Devil and the Deep Blue Sea

Recommended Posts

Stacking: Caught between the Devil and the Deep Blue Sea

 

My struggle with stacking focus has been going on for years. Lately, mostly because of the advent of the new Zeiss Otus series of apochromatic lenses, I have segued into deciding should I stack at all. What I have been doing recently is stacking photos at a wide-open (and fast) aperture and, after the stack, I also take a separate traditional single-shot photo at the highest aperture I can get away with. I compare the two results, the stacked image and the single-shot photo. The results are fascinating and somewhat disturbing.

 

Before I sing whatever praises I may have of focus-stacking, let me explain what I find disturbing about this comparison. For one, unfortunately the process of stacking images alters the color in the image somewhat and I find it very difficult to match that color later in post. Until I started taking (along with a stack) a single-shot photo at high apertures, I was mostly unaware of the differences between the two because I am not in the habit of developing the stacked-layers before I stack them, but only the final stacked image. In other words, I seldom see what the developed layers for a stack look like compared to the final stacked image because I never develop them.

 

Aside from a color-shift between the stacked and none-stacked photos in the comparison, the single-shot image also seems to have more luminance. Another effect (I may be imagining) is that the stacked shot has more trouble softening reflective-light (highlights) resulting in a bit of unwanted (and unneeded) contrast. The resulting effect is that the stacked image is a little crude or harsh compared to the traditional single-shot photo.                                                

 

As for the merits of the stacked image, with it I am better able to control what is in focus and what is bokeh. That is the advantage of focus stacking. And most of all, by stacking at low apertures, I can keep the subject in sharp focus while having the background be whatever I want it to be, like a lovely bokeh. I can’t do that with a single-shot photo at high apertures because the increased depth of field also overwrites any sense of bokeh that is present, so, once again, there is no free lunch.

 

One compromise I could try is to take a single shot photo at high aperture and a second shot wide open and paint in the bokeh background from the second shot into the first in post. However, I don’t like the artificiality of this approach, not to mention the endless retouching it brings into play. I do enough retouching with stacked images as it is.

 

In summary, I feel I have pretty much explored the possibilities of shooting at low and high apertures, stacked or not-stacked. Perhaps this exercise could be more conveniently described as developing my technique. In that case, after all these years consider my technique more-or-less developed. Perhaps I am finally ready to take some photos.

 

Here is a stacked photo and a single shot photo taken at a high aperture. Note that the stacked one has a slightly more limited view because the stacking process, especially on a focus rail (as this one), restricts what is in frame. Notice the loss of contrast in the stacked image. It is also less bright. I know. I am probably splitting hairs here.

 

My takeaway so far is that I will be taking more single-shot photos going forward. However, as this separate stacked photo demonstrates, I also will continue stacking. Stackers out there, what are your thoughts and your experience with this conundrum?

 

Nikon D810, CRT Nikkor-O, Zerene Stacker

post-2886-0-58117800-1427961228_thumb.jp

post-2886-0-38540500-1427961235_thumb.jp

post-2886-0-36799400-1427961243_thumb.jp

  • Like 4

Share this post


Link to post
Share on other sites

Usually I am not that interested in macro, for a number of reasons.

It begins that I don't have the patience, and further as you have shown so well numerous times, it requires impeccable technique and expensive exotics to give the best results.

 

However, I have to say, this post is very interesting and the images, especially the first two, really show the point you are trying to pass.

Stacking as you say is not about bringing everything in focus, but to have complete control over what is in perfect focus and what is nicely defocused. The perfect blur in the background and the perfect focus of the pistil in the stacked shot are superior compared to the traditional shot, however the colours and the tome, especially in the brighter parts of the flower, are so much better in the latter.

At the end of the day  I don't know what works best. Probably a mixture of the two, with some blending.

Share this post


Link to post
Share on other sites

My thoughts exactly. It may have to be a mixture of the two. The color-thing is the most painful part. I am going to look into this... a lot.

Share this post


Link to post
Share on other sites

Michael I'm very curious( I'm in no way suggesting you don't know what you're doing obviously you do) but, have you tried stacking with the latest

version of photoshop using blend images?

I've tried a few and am not noticing any variation in colour, perhaps my subjects haven't been as demanding as yours!

 

It's likely the reason for the colour variation is something I don't quite understand, your thoughts would be appreciated.

 

tony

Share this post


Link to post
Share on other sites

Photoshop was the worst stacker I ever used, but that was some years ago. I tried stacking this same series of images in Photoshop CC, the latest version. It is still takes a terribly long time to stack this. As you can see the artifacts are not only numerous, but huge. As for the color, I would have to do more experimenting. My question to you is:

 

How would you go about selecting one of these layers to overwrite portions of it to the final image. Not sure how to do that. To get the final image, I have to merge the layers into one, and I would need each individual layer to step through to find where to paint over. Any ideas how to do that?

post-2886-0-37271700-1427982488_thumb.jp

Share this post


Link to post
Share on other sites

That is just the basic align and blend that has been there for years. What I would like to know is that for retouching we need to take from each original image. Not sure how to do that in PS.

Share this post


Link to post
Share on other sites

Michael this video covers using the layer masks within the stacking process, much of the tutorial is very basic, if you watch from about 14.00 into the video.

 

Share this post


Link to post
Share on other sites

Thanks, I see the approach, but it is prehistoric compared to Zerene Stacker IMO. Photoshop has had years to perfect this techique, and they come out last every time. With the money they have to hire this done, the only conclusion I can come of with is that they are not interested. 

 

It is the nature of the sampling beast that color cannot exactly be maintained, so there will always (to my understanding) be discrepancies between a singlt-shot's color and a stacked photo. My approach is to use the best APO lenses going in.

Share this post


Link to post
Share on other sites

Stacking and stitching are both areas where dedicated software such as Zerene Stacker and PTGUI and Auto Pano Giga (stitching) are streets ahead of "one size fits all" programs like Photoshop. The additional controls available on these separate programs simply are not available in the Photoshop equivalents. The programs are also a lot more refined in their results and much faster in operation, which is to be expected.

Share this post


Link to post
Share on other sites

Funny cos I was the last to sing the praises of photoshop but it's a fact I can create stitched panos and focus stacked images in

photoshop cc which give very satisfactory results and I've always been very critical on image quality!

My focus stacked images are better from photoshop than with Zerene Stacker and my panos are as good as they need to be and stand up very well

even when printed 40" wide!

And yes I've only been using photoshop CC for a couple of months.

So I'm happy :)  

  • Like 1

Share this post


Link to post
Share on other sites

quote: "Until I started taking (along with a stack) a single-shot photo at high apertures, I was mostly unaware of the differences between the two because I am not in the habit of developing the stacked-layers before I stack them, but only the final stacked image. In other words, I seldom see what the developed layers for a stack look like compared to the final stacked image because I never develop them. "

 

   Did you ever try batch processing the images to match the color before stacking them?

 

   P.d.: I´ve never tried stacking myself, just an idea.

Share this post


Link to post
Share on other sites

I have tried developing the color before stacking, but the problem is inherent in the idea of sampling as I understand it. 

 

It depends more on the quality of the lens correction, at least in my experience.

Share this post


Link to post
Share on other sites

Would you observe less colour shift between the stacked and the one-shot image, if you used a camera with a Foveon sensor, that records full RGB information for each pixel? I.e. I'm asking, if the Bayer sensor pattern has a negative impact on colour fidelity when applied for stacking.

Edited by bjornthun

Share this post


Link to post
Share on other sites

I understand. However, Photoshop is very, very slow. I just tried it again. Zerene Stacker runs circles around it, and when it comes to retouching, Zerene is the best I have found. Photoshop is very difficult with retouching. It is like they never sat down and thought it through. 

 

As to the Adobe RGB TIFFs, I believe you are mistaken. I send ProPHoto RGB TIFFS to Zerene Stacker, always.

 

But just to check, I have written to Rik Littlefield, the author of Zerene Stacker, to check and will post his answer here.

Share this post


Link to post
Share on other sites

I have 128 GB of very-fast RAM in my computer. Rik Little field responds that:

 

"ProPHoto RGB is one of the default colorspaces that can be specified when the Lightroom plugin is created by Zerene Stacker. It's in a pulldown list accessed at Options...> Lightroom. It can be changed by just re-creating the plugin

Share this post


Link to post
Share on other sites

Zerene has two options regarding ProPhoto outside of the LR plug (I don't use LR either), both of which are relevant to the use of Tiffs as opposed to raw files.

 

The objection to Tiff I cannot understand - what possible benefit is there in using raw files into the stacker - the stacker only has to then do the conversion itself before stacking. Anyhow, processing the raw files, saving to Tiff and then working on that tiff is probably the universal workflow in any other process one may use in photographic manipulation.

 

The options for Zerene  in Colour Management are:

 

Option 1: "Use EXIF/DCF rules" or "If the input file does not embed a profile, use the following: - (ARGB, sRGB)". Choosing the first with tiffs saved in ProPhoto results in an output file tagged ProPhoto depending on Option 2 (below). If you don't save with a tagged file, only then is the option just sRGB or ARGB.

 

Option 2: "Output options": "Copy profile from input" completes the ProPhoto flow.

 

Photoshop will not prompt for a profile if its normal colour space is set and managed as ProPhoto, confirming that the image is ProPhoto.

 

Equally one can opt out of colour management in Zerene and assign ProPhoto profile to the finished stack in Photoshop. Either way the colours are the same and appear as full, deep ProPhoto, matching the original individual stack Tiffs saved as ProPhoto.

 

During the stacking the preview panes are displayed with rather dull looking sRGB colour, however.

 

Throwing a 131 shot stack at both  resulted in a similar time from load to completion between Photomerge and Zerene, but the accuracy of Zerene knocked Pm out of contention (duplicating what Michael found in his comparison earlier) but I'll post these unretouched straight 100% sections anyway to demonstrate that the ProPhoto colour is identical, aside from showing the PhotoMerge "it's too hard, here's an average tone to fill" missed bits.:

Zerene:

LyIw72z.jpg

PMerge:

VFPFiiz.jpg

 

Zerene did crop in a bit, hence the slight difference in image size of these 100% views.

Share this post


Link to post
Share on other sites

Here is the straight scoop from Rik Littlefield, creator of Zerene Stacker:

 

As far as I've seen, whenever you export from Lightroom using ProPhoto RGB, Lightroom embeds a copy of the ProPhoto RGB profile inside the input files.  In that case Zerene Stacker will work in ProPhoto RGB and will write its output files in ProPhoto RGB, with an embedded ProPhoto RGB profile.  In other words, the output files are the same profile as the input.

When images are displayed by Zerene Stacker, within the Zerene Stacker window, there are two different ways for how the input color profile is handled.  This is controlled by Options > Preferences > Color Management > "Use input file profiles for ZS screen displays".  If that option is NOT checked, then (only) for its own screen displays ZS acts as if the input were sRGB.  If the input is actually ProPhoto RGB, this will cause images displayed inside ZS to look washed out.  If the option IS checked, then for its own screen displays ZS will apply the ProPhoto RGB profile and will display like Photoshop.  Either way, the output files will be still tagged as ProPhoto RGB, with an embedded profile, and will be interpreted correctly by Photoshop et.al.

The only way I know to get into trouble would be if an input file were somehow tagged as being ProPhoto RGB but did NOT include an embedded ProPhoto RGB profile.  I don't know if it's possible to get Lightroom to do that, and the question has never come up before. 

The option "If input file does not embed a color profile..." is in there because some cameras write image files that are actually Adobe RGB, but do not embed the Adobe RGB profile, and may not even follow the standard rules for saying that they're Adobe RGB.  I have never heard of an image being ProPhoto RGB but not including that profile.

 

Share this post


Link to post
Share on other sites

Exactly as I understand it as well, Michael. If you save a Tiff as ProPhoto from any raw processor, Zerene will deliver a ProPhoto image, unless you specify otherwise in prefs.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×

Important Information

By visiting this website you are agreeing to our Terms of Use, Privacy Policy & Guidelines.