Practicing The Craft: Stone sculptor take 2 ~ a 43 frame stack

[JohnRostron]

I like it.

Thanks Brian. I thought I would try this outside at a scale comparable to yours, so I had a go at a Potentilla bush in my front garden. The focussing worked OK, but unfortunately the wind got up just sufficiently to prevent the foliage from stacking. I shall have to find a few rocks to try it out on.

John

[ajohnw]

I'm inclined to agree with Manfred's comment on the rocks shot but think that photo people have a tendency to forget another aspect of why people might focus stack and that is resolution. The best example of that is probably insect shots taken with microscope objectives or even lenses with supplementary lenses fitted. It's somewhat dependent on the resolution the subject needs. This is a resolution test of a tamron f2.8 macro lens.



So if the detail in the subject warrants it shots should be taken at 5.6 or 8 and then stacked but as Manfred says given distance and size plus reduction of a full sized image to web size a single shot with a suitable aperture would probably have been ok. Another point as well - is it best to stack before or after size reduction? I think if as suggested Brian took 3 or 4 it would be best to reduce before stacking to get the best results from the stacking software. The acceptable depth of field assume certain aspects about final image sizes etc the image on the sensor doesn't know what size things will finish up at.

John
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[Manfred M]

John, while I agree that resolution is one reason that one would focus stack, this is also true for why people shoot a pano, rather than cropping a wide angle shot.

On the other hand, that level of resolution can be important if one makes large prints for pixel peepers, but if one prepares images to be viewed on the internet / social media where the largest dimension is often around 2048 pixels, all that resolution does not really add value.

[Stagecoach]

Thought that I would show you what my cardboard cut-out gizmo looked like:


The near ring, with the pointer, is fixed and the far ring, with the gradations, rotates with the focus barrel. This is fixed fairly firmly by an elastic band! I note the position on the dial of the near and far points and then interpolate, using one, two or three ticks on the outer dial, as appropriate.

John

Very snazzy John.

[Wavelength]

Well done Brian; John's self made accessory is really great !!!

[JBW]

Well done Brian; John's self made accessory is really great !!!

agreed

[ajohnw]

John, while I agree that resolution is one reason that one would focus stack, this is also true for why people shoot a pano, rather than cropping a wide angle shot.

On the other hand, that level of resolution can be important if one makes large prints for pixel peepers, but if one prepares images to be viewed on the internet / social media where the largest dimension is often around 2048 pixels, all that resolution does not really add value.

I've been intending for find out if stacking for resolution does offer any advantage Manfred. I suspect it will within limits. Also the reduce or not reduce and post process before stacking aspect. The depth of field does depend on final image size and in real terms on the web 12 to 14 hundred pixels is the usual size limit. As I'm now using a 40" monitor I have a much better idea what the eye can usefully accommodate in one go from the usual viewing distances.

On m4/3 thanks to physics/practicalities I can take shot up to 80lp/mm at the centre at f4 but oly have optimised for macro work so edge drops off to 60. At F16 it's more or less the same as Brian's in this respect but even across the frame.

My interest in this area perked up recently due to a plant my wife bought. Also I believe that if I upgrade my E-M1 firmware it will advance the focus point automatically. Not sure what will happen if it's set at 1:1 though so might have to use a rail. Some "extremists" do - driven by a stepping motor. For the amount of use I would have price rules that out.

John
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