To stack or not to stack

mawyatt2002 wrote:

gardenersassistant wrote:

mawyatt2002 wrote:

gardenersassistant wrote:

I use stacks not for the detail you can see if you zoom in, because I produce images for viewing "as is" without zooming in on them. I use stacking because I like the look of the images I can produce using it.

Nick,

Interesting comment. Can you elaborate more on the "look" stacking gives? Is this the in focus areas or the out of focus areas, bohea so to speak?

Best,

Both the in focus areas and the out of focus areas.

One of the reasons I use aperture bracketing (for non-stacked images) is that it gives me a set of images from which I can choose the one(s) which have the balance between the amount of the subject that is in focus and the rendition of the background that best pleases my eye.

For a lot of people a highly out of focus background is very pleasing, and some prefer more or less, or completely, featureless backgrounds, for example replacing a natural background with an artificial one by placing a card behind the subject. I generally prefer more going on in my backgrounds than that, and I prefer natural backgrounds, and I spend time exploring angles of attack looking for ones which produce a background that seems to me to be more or less harmonious with the subject in terms of lines, shapes, textures and/or illumination. And with single images you tend to get a smooth transition between the in focus and out of focus areas (unless the entire subject is rendered in focus against a background that is relatively far away and out of focus; with the whole subject in focus and the whole background out of focus this is not problematic).

Sometimes I can find a single-capture image of a scene that gives a combination of in focus and out of focus areas, and a transition between them, that pleases my eye. Sometimes I can't.

Sometimes when I can't get a balance that I like between subject coverage and background rendition with a single-capture image, I can get it with a stacked image. In fact, I'm finding that that is quite often the case. I haven't counted, but I would guess that at present I'm choosing to use a stack for perhaps two thirds or so of the scenes and single-capture images for the rest.

Stacked images can have a different look from single-capture images, with a rather sudden transition between the in focus and out of focus areas. Sometimes this can look similar to the subject-against-a-distant-background look of a single capture image, but sometimes there can be a rather jarring transition, for example if a stem, branch, leaf or petal jumps from being in focus to out of focus. I try to pick the rearmost element of the stack such that the transition isn't too jarring, but sometimes I can't find a suitable break point. And one of the curious things about capturing images (or mainly videos in my case) for stacking is that I can't compose with the final image in mind. With single-image captures I can either see before capturing, or immediately afterwards, what the final image will look like. For stacks I can't. It is only when I do the stacking and find out how the transition falls that the look of the image emerges, for better or worse.

And sometimes a stack that looks ok in terms of composition is spoilt by artefacts that either I can't get rid of or that need more time to fix than I'm prepared to spend on it. When I started out with stacking I would spend ages on an individual image, but now I've got a much better grasp of what will work and what won't, and I don't spend long on any single stack. Once it starts getting time-consuming I drop it and move on.

Sometimes I can't find a single-capture image or a stack of a subject that I like.

I've written at some length about using a combination of single-capture images and stacks for botanical subjects. You might want to have a look at this post here at dpreview, which is quite short, and mainly images. If you are interested you might want to click through from there to a more substantial set of posts on another site with a lot more discussion of various issues to do with stacking, and not stacking.

Nick,

This appears the stacking is also improving the effective resolution as well as creating a pleasing background. The stacks were using f2.8, while the singles were f8 or f11 which explains the apparent resolution improvement.

Yes, f/2.8 is close to optimum for sharpness with that lens. The reason I don't use the slightly better f/4 or (arguably) very slightly better f/5.6 or f/8 for stacks is to keep the shutter speed up for hand-holding while trying to stay at or as near as possible to base ISO. (I use an auto-ISO setup that handles both aspects for me so I don't have to think about it and can concentrate on composition etc.)

I do wonder if there is something else going on as well. Presumably as the camera traverses the scene there are often several images in sequence which have a particular area in focus. I wonder if the stacking makes any use of that extra information? (similar to median stacking for noise reduction, done locally on focus-overlapped areas, but for sharpness/detail rather than noise).

Agree, I like the stacked images better, but all are very good.

Thanks.

When imaging fast moving subjects like race cars, blurring the background often gives a sense of speed. But generally you don't want the subject to be blurred, so panning with the moving subject keeps the subject sharp but burs the background during the exposure. Your interesting use of stacking seems an analogy in that you are moving the lens or focus, effectively sweeping the background while the subject is sharply in focus.

That's a novel way of looking at it. Not sure I can quite get my head around it as the lens does in fact focus right to the furthest background. I just dump those images from where the focus traversal moves beyond the furthest point I want in focus.

It is tempting to think of the background as being what is in the furthest frame that I keep, but it is more complicated than that. Depending on the method and parameters being used backgrounds can get mucked around with (noise, colour shifts, desaturation, posterisation, artefacts). Hmmmm, I'm wondering if you might ask for examples - but I don't recall seeing much of that recently. I wonder why not. Perhaps I'll play and see if I can generate some nastiness to remind myself about it.)

Very interesting concept indeed, thanks for the reply.

You are very welcome. I like rambling on about this stuff.

Best,