Trying out some focus-stacking


OldTaffy

Link Posted 21/05/2022 - 18:57
Dandelion seed-heads are beautiful if one looks carefully before binning them. I threw away two, then saved this less-than-perfect one to try out some focus stacking. Robert L. stacked 17 frames for his 'Look what I pulled out of the border' (30 April) but only 6 for his earlier goats-beard seed head. Does one really need to stack so many? The more the better seems the answer.

The first image is the result of a stack of 3 exposures, the second is from 13 frames stacked. The whole jpeg frame. No cropping, no photoshopping apart from resizing from 6143x3839 to 1200x750 pix which does limit how much one can appreciate in fine detail.

Pentax K-S2, ISO 800; DA 35mm f/2.8 macro Ltd. Seed head clamped, camera clamped firmly 20 cm away. One light bulb illumination. I refocussed manually for each frame, shifting the focal point by about 1 mm, keeping distance fixed. (I had tried stacking on a small wasp nest a while ago, moving the camera, but this caused perspective change that messed up the final image). Software: free CombineZP.




A few of my photographs in flickr.
Lizars 1910 "Challenge" quarter-plate camera; and some more recent stuff.

K10D

Link Posted 21/05/2022 - 19:46
Great result! Not too much discernable difference to me at least.

Best regards

Lubbyman

Link Posted 21/05/2022 - 20:37
An interesting pair of stacks. There is indeed not much discernable difference at the image size in the thread. But click on the images and the larger versions are definitely different - the latter (13 stacked images) is much sharper across the whole seed head.

But which is the better? If you want lots of sharp detail everywhere, then it's the second image. But if you want some areas of softness (the seed head is, after all, a soft and fluffy thing), then it's the first image. So whether it's 'the more is better' depends on what you want. As always, the technology must be the servant of the artistic vision!

Steve

OldTaffy

Link Posted 21/05/2022 - 21:25
Lubbyman wrote:
... So whether it's 'the more is better' depends on what you want. As always, the technology must be the servant of the artistic vision!

Steve

That is a most interesting comment. As a retired scientist, with zero artistic talent, I suppose I was looking for maximum detail. Fuzziness upsets me

Thanks for your perspective.

Martin
A few of my photographs in flickr.
Lizars 1910 "Challenge" quarter-plate camera; and some more recent stuff.

RobL

Link Posted 22/05/2022 - 16:15
One aspect of focus stacking I have never found a satisfactory answer to is that the subject changes in size within the frame as you focus from front to back, whether you are moving the front of the lens or the whole camera body. The only way I can think is if a macro lens has internal focusing and you focus with the lens, but I havenít seen any that are built that way. Given that whatever software you use has to compensate for this I find that the more steps you use the better it is resolved. I think using a longer focal length helps as well, my default for stacking being the 100mm macro.

I am impressed that you managed an acceptable stack with only three images!

Lubbyman

Link Posted 22/05/2022 - 16:44
OldTaffy wrote:

That is a most interesting comment. As a retired scientist, with zero artistic talent, I suppose I was looking for maximum detail. Fuzziness upsets me

I used to be a scientist, too. Then drifted into engineering circles and discovered 'engineering judgement'. Never did find out what it meant, other than "I say it's X, I'm an engineer, don't argue with me." (Steve now runs for cover to avoid the wrath of engineer members of this forum...).

As for zero artistic talent, I used to think the same about myself. Until the day I went to the opening of an art exhibition to take snaps of some friends who were exhibiting. Got talking to a local press photographer who was covering the event for his paper. I said I had no artistic understanding or talent, unlike the people who had produced the exhibits. His response was 'Nonsense. You've got a camera so you're an artist!'. Who was I to disagree???

Rob - the Irix 150mm macro has internal focusing but not sure whether the subject changes size when focusing with the focus ring as I use a focus rail when taking shots for stacking. As you say, the software has to compensate for change in size (and a lot else, too!) so the more help you give it the better the chance of a good result.

Steve

davidwozhere

Link Posted 25/05/2022 - 00:57
Combine ZP takes account of the relative size 'problem' and resizes the entire batch to uniform dimension before combining them. The only problem I find with it is that the edges tend to be a bit ragged so it is as well to allow a bit of 'waste' around the edge of the images so you can crop it off at the end. Also, remember that it is a garbage in > garbage out setup so make sure every image is as pristine as you can make it before you start.
Both the *istDS and the K5 are incurably addicted to old glass

My page on Photocrowd - link
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