Layer scaling (distorting) Vs moving while focus stacking

Hi guys,

sorry if I ask in the wrong section, this seemed to me fitting the best .. and also sorry if this q: is noobish or ignorant .. I just don't know the right answer even after searching ...

I started relatively recently with focus stacking ... When I stack images taken with my 70-200/4 I am fighting a lot with that there's small focal length shift if I change my focus point and I have to address it ... You can see a small green-ish halo around the edge of the boulder with moss in the foreground ..

I've found that there are two options (or techniques)

1) I can make a layer a 50% transparent and then move it to match the edges with layer below .. this is not always working because as there seems to be a small focal length shift it will not match by few pixels elswhere ..

2) I can just start stretching and distorting layer on the top to match the layer below - this is usually very tedious work

Also I am fighting a lot sometimes around that edge while using brush on the mask to have the seamless joint between two layers ..

Can you please somebody gimme your steps just on high level how you exactly solve this problem while focus stacking that the two (or more) layers don't match because of small focal length shift due to changing a focus point and focus distance ?

Shots below are focus stacked .. both are made of two images and I've spent with both quite some time and it was bit tedious work and I felt like if I really miss something and doing something sub-optimally ...

Please let's make it generic and not particular software bound so let's assume that I am working in that with a raster/bitmap editor supporting layers and merging together two tiff or jpeg images exported from RAW after processing them in software for RAW files developing

thanks much and regards, ~dan

I don't think I've ever attempted focus stacking hand-held shots (or only two for that matter).

You might get more help by asking in the MACRO AND STILL LIFE forum. Many folks there stack.

So, I usually stack shots that were taken on a tripod and/or on a tripod with a focus rail.

Often when stacking you need to toss out shots that you know are going to mess up the stack.

grsnovi said:

I don't think I've ever attempted focus stacking hand-held shots..

Click to expand...

Hi, thanks for input ... but I am stacking shots taken with tripod ... my question doesn't have anything to do with tripods or handheld shots but with that it can happen - especially with longer glasses and big distance between focus points - that the focal length changes slightly with focusing so the pictures with different focus point (no matter if from tripod or handheld) are not perfectly aligned ... this probably doesn't happen that much with for instance wide angle lenses or with macro lenses with paper thin DR but shots below were fire with something like 100-120mm and there's quite some difference in distance to foreground (the closest element in the focus) and the background

I think what you are experience is called "focus breathing", whereby the field of view changes slightly as one adjusts focus. See https://en.wikipedia.org/wiki/Breathing_(lens) . Some lenses exhibit it more than others; you might have to try several lenses before finding one that works for you, or ask in a Nikon group or perhaps the Macro group about recommended lenses that minimize this effect.

You might get better results by using a focus rail (to move the camera and lens closer or farther from the desired centre of focus) so you don't have to touch the lens's focus ring - after the initial set-up of course. However, that's more commonly used in macro photography where you would typically adjust the rail by a millimeter or two between shots; I don't know how practical it would be for the type of scene in your example where a larger adjustment would be required.

Finally, I know you didn't want to talk about software, but I think it really is worth trying the demo versions of all the stacking software you can find, such as Zerene and Helicon Focus, to see whether they have any automation that can compensate for what you're experiencing.

Best wishes,
Sterling
--
Lens Grit

Hi Sterling,

thanks for input ... maybe I was not clear .. as a landscape photographer I just did a second shot for the very close foreground .. I am not stacking many images like if I was shooting some macro or something alike ... I am just asking how you fellow photographers deal with such a common situation in postprocess (assuming that you blend two or max three layers) ..

I've been stacking in past many shots but as pointed above there's no problem with wide lenses in general .. I've hit this issue this time with longer lens and as you could see, I've stacked pictures already "somehow" .. I am just asking on what your process is to eventually improve my own ...

Everybody who is focus stacking with almost any lens have to deal with small focal length shift .. it can be few pixels or it can be something bigger like if you're shooting with f8 at 135mm and switching between infinity and the subject in the close foreground ...

I doubt that landscape photographers use rail (haha) or use some special software to just blend a close foreground to the main shot