Snowy Crocus

Well processed, Mark. An interesting subject and back story! I wonder at the need for stacking at f/22, but I don't question the results.

Wow, Jan. 29? Well, the weather is getting stranger and stranger. . . Great classic capture of Crocus in the snow, Mark. I like the grouping of the 3 buds at various height levels. Great details from all your stacking. The lighting certainly helps add a cold feel to this image. Brrr!

Phil, In any stack with overlapping sharp areas there will be artifacts (it's a fundamental law of optics related to the circle of confusion and how things go out of focus). You can minimize these by using an f stop which gets both the front and back areas acceptably sharp. In addition, for macro work like this where I'm approaching 1:1 magnification, depth of field at large apertures, say f/4, is less than a millimeter. This makes it hard to manually adjust your focus while getting overlapping sharp areas from one frame to the next. I use small apertures to give me the best chances of success with well overlapped sharp areas and to minimize artifacts. I've "tested" this lens and camera and found that I cannot see any difference in sharpness for f stops up to f/25. At f/29 and f/32, I don't notice a sharpness loss, but I do see an overall loss of contrast. My experience is backed up by on-line dof calculations showing dof for a 100 mm lens at a focus distance of 15 cm (about 1:1 magnification). These show that the dof at f/4 is +/- 0.1 mm while at f/22 it's +/- 0.5 mm. While I could have opened up to something like f/13, I'd probably not have been successful at f/8 or wider and there would have been a lot more artifacts to clean up in post processing.

Love the detail you've achieved Mark. I really enjoy the mix of textures between the snow, the water drops and the flower itself.

Also - thank you for the post on stacking and DOF. I had never really heard of stacking (certainly never tried it) before finding NPN and am grateful anytime a process like that is described, as it helps so much!

This is a very beautiful photo Mark. Love the way the purple blends to orange in the crocus. Nice piece of art! Some day I'll have to learn a bit about macro and this stacking technique.

Mark, congratulations on the weekly pick. I have no macro lens, yet, so your f-stop discussion was helpful for the future. Seems to be a little ccw lean to the flowers. The phase combo of the snow crystals and the water drops on the petals is nice.

Congrats on the WP!
Sandy