Back Lit Neomarica

[Round Tuit]

This is only the second photo taken with my new 100mm f/2.8L macro lens. It is a focus stack of three shots manually focused. I am not completely happy with the result as the little droplets are not as sharp as I would like. I probably should have used at least five shots. Live and learn.



Comments always welcomed

[Geoff F]

Looks OK to me.

I find that with focus stacking the more shots you take the more chances there are for something to go wrong with the editing; particularly when the auto masking goes slightly askew and you have to manually edit the masks.

[Round Tuit]

Looks OK to me.

I find that with focus stacking the more shots you take the more chances there are for something to go wrong with the editing; particularly when the auto masking goes slightly askew and you have to manually edit the masks.

Thank you Geoff.

I have done many stacks of 25 or more photos yet never ran into this problem. I use Zerene Stacker for stacking. Their Dmap algorithm frequently creates "halos" on deep subjects but their retouching feature is very effective at correcting them and is easy to use.

[DanK]

I also use Zerene DMap for almost all of my stacking, usually retouching from a PMax composite.

I think it's worth separating two different conditions. Doing handheld field macro, camera or subject motion may be more than the alignment algorithm can handle. Then one might get an image that has to be tossed, which in turn may leave a gap in the stacking.

However, in working with tripods and stable subjects, I have never had any problems arising from too many images in the stack. In the case of Zerene, you can actually watch DMap work, and you can see why this is not a problem. It works through the stack, replacing blurred areas with sharp pixels when if finds them.

For shots like this, I normally deliberately start the stack a bit in front of the closest part of the subject and keep it going well past the back. This adds an annoying step--going through the stack to identify the first and last needed shots and discarding the rest--but that doesn't take very long, and it eliminates the risk of finding blur in extreme parts of the image.

Apart from a few droplets, this composite seems to have worked well. However, it seems kind of harsh. My first question was stacking method, as PMax sometimes creates that sort of look, but you answered that question. So, my guess is that the cause is lighting. How did you light this?

[Round Tuit]

I also use Zerene DMap for almost all of my stacking, usually retouching from a PMax composite.

I think it's worth separating two different conditions. Doing handheld field macro, camera or subject motion may be more than the alignment algorithm can handle. Then one might get an image that has to be tossed, which in turn may leave a gap in the stacking.

However, in working with tripods and stable subjects, I have never had any problems arising from too many images in the stack. In the case of Zerene, you can actually watch DMap work, and you can see why this is not a problem. It works through the stack, replacing blurred areas with sharp pixels when if finds them.

For shots like this, I normally deliberately start the stack a bit in front of the closest part of the subject and keep it going well past the back. This adds an annoying step--going through the stack to identify the first and last needed shots and discarding the rest--but that doesn't take very long, and it eliminates the risk of finding blur in extreme parts of the image.

Apart from a few droplets, this composite seems to have worked well. However, it seems kind of harsh. My first question was stacking method, as PMax sometimes creates that sort of look, but you answered that question. So, my guess is that the cause is lighting. How did you light this?

Thanks Dan,

I have only stacked indoors and using a tripod. I am no longer steady enough to stack otherwise. Like you I start the stack in front of the subject and go past its back portion. I also usually include more frames than absolutely necessary as it is easier to discard excess frames than to find that you have a gap in your stack.

For this picture, I used the Pmax algorithm. The flower was back lit using a soft box and I used a black foam board as a background. Some light spilled on the background so it had to be darkened in post. I also might have over compensated for the softness when sharpening in post.

[Geoff F]

I use Photoshop for my editing of subjects like insects or flowers and often find it creates wider than ideal masking on parts of the layers. For example, I get an insect leg with the surrounding area out of focus where there should be sharply focused background.

This means I have to manually edit the masks on various layers to remove the out of focus bits and brush in the sharply focused areas. Deciding which layers require editing often gets me totally confused.

I tried Zerene a few years ago but found it to be very slow and no better than Photoshop. Perhaps it has recently improved.

[DanK]

For this picture, I used the Pmax algorithm.

I suspect that is part of the issue, although oversharpening could of course also do it.

I use Photoshop for my editing of subjects like insects or flowers and often find it creates wider than ideal masking on parts of the layers. For example, I get an insect leg with the surrounding area out of focus where there should be sharply focused background.

This means I have to manually edit the masks on various layers to remove the out of focus bits and brush in the sharply focused areas. Deciding which layers require editing often gets me totally confused.

I tried Zerene a few years ago but found it to be very slow and no better than Photoshop. Perhaps it has recently improved.

I believe photoshop uses a depth map algorithm. These are particularly prone to haloing when there is a substantial distance between two parts of the subject. That sounds like it may be the problem you describe. The pyramid stacking algorithm (PMax) in Zerene is much less susceptible to this problem. Since Zerene has a superb retouching tool that allows you to paint from either an individual image or another composite onto the composite you want, I routinely deal with this by creating both DMap and PMax composites and painting from the latter to the former in areas that have that kind of blur.

Zerene, unlike Photoshop, also allows you to set some of the parameters of depth map stacking (contrast, estimation radius, and smoothing radius) that help lessen this problem. See https://zerenesystems.com/cms/stacke...ls/tutorial003.

The PMax algorithm, the controls over depth map compositing, and the superb retouching tools are the main reasons I use Zerene for all of my stacking. Out of curiosity, I did some speed tests many years ago, and unlike you, I found Photoshop to be substantially slower in large stacks. However, speed is less important to me than control over output.

The one serious competitor to Zerene is Helicon, which I have never used.

[Round Tuit]

Here is a link to the full size (6000 x 4000) unedited PMax file for your info.

I will delete this file in 2 weeks. Full size PMax output

[DanK]

With the full size image, I can see blurred drops in the middle of the stack as well as the back.

Normally, this would suggest either too few images (missing one with those areas in focus) or slight subject motion. However, it looks like other things on the plane with the blurred drops are in focus, and IF that is so, that obviously rules out a missing image in the stack.

I found I often had problems with slight motion of flowers while I was using a DSLR. My routine was cumbersome. I would always use mirror lockup. I would take one shot, adjust focus, and then stand still for a while letting the motion I had generated die down. then I would take another shot and repeat. This could take quite a while.

Now that I have a mirrorless camera with automatic focus stacking, it's simpler: I set the shutter to electronic and then just stand very still while the camera quickly generates the stack.

It would be interesting to create the same composite with DMap and compare. This obviously wouldn't help with the blur, but I suspect textures and color rendition would be a bit better.