I know we've discussed this before, and I hope this may prove of some interest to you.
The main problem facing the average amateur photographer using an SLR to take macro images is the incredibly small depth of field we have to work with. As a generally rule, the higher the magnification, the shallower the range of focus. Stopping down the aperture of the lens helps, but only to an extent.
Photoshop solves the problem with their 'Focus Stacking' feature. You shoot a series of identically framed and exposed images, the only difference in each photo is the point of focus. A three-image stack would involve focusing first on the nearest point of the subject, then at a half-way point and finally at the furthest point of the subject. Photoshop can detect which part of each image is in focus, and by using various blending and masking techniques, combine these sharp portions of each photo into one composite image.
As I am famously renowned for being as tight as a duck's arse, I've found a way to perform this process inside (the much cheaper) Photoshop Elements (I'm currently on version 11), with the help of the incredibly feature-packed
Elements XXL plug-in (and excellent value at just $49.95/£30ish).
XXL works as a plug-in inside Elements, and adds a lot of the features only found in the flagship Photoshop products. Best of all, in my opinion, is that XXL fully integrates with all the menus in the host, so unlike some plug-ins, the various feature interfaces are available directly without having to export one's image to the plug-in. You can even choose to highlight the XXL features with a blue background, so they stand out in the menus from the regular commands.
Here's how the Layers menu looks with the added XXL stuff (enhanced this to show it better):
Elements XXL contains two invaluable features for the macro photographer, and gives you similar capabilities to Photoshop's Stack Focus -
Auto-Align Layers and
Auto-Blend Layers.
Here's an example I put together to show how cool these features are.
First I took a series of five photographs - although not macro shots, they serve to illustrate the power of the XXL plug-in. I switched off autofocus and as you can see, I've focused manually at different distances into the subject from the tail of Thunderbird 2 through to the front of Thunderbird 3:
I chose one of the images to act as the base image, and opened this in Elements. I then opened the other four images, copied each in turn, and added them each as a separate layer on the base image:
The first problem we encounter is that even though I took all five photographs on a tripod, the physical action of moving the lens elements around to focus each time means the five images don't quite line up perfectly. You can really see this in this animation, the asterisk marks the focus point for each image:
XXL can correct this with its
Auto-Align Layers feature. You first select all the layers and the command is found in the
Image menu:
You even get different options to align the layers:
In this example, I left it in 'Auto' as shown above.
You can see in this screenshot that the layers have been moved to align them correctly. The transparent areas around layers 1 to 4 show that they've each been shrunk slightly to fit over the base layer (now automatically relabelled as '0' and which remains unchanged):
Apparently (I haven't tried it yet), XXL's Layer Align even works with hand-held shots where it's impossible to frame each photo identically. This is a boon for anyone who shoots bracketed exposures for High Dynamic Range (HDR) images (a technique where 3 images are taken of the subject: one correctly exposed, one under-exposed and the other over-exposed; the three photos are later combined so that the final images has correctly exposed highlights and shadows, normally impossible to achieve in a single HDR shot).
Back to my example, and finally, you make certain all the layers are selected again, and then use XXL's
Auto-Blend Layers feature (also found in Element's
Image menu):
Auto-Blend features two methods,
Panorama and
Stack Images. For my example, I used
Stack Images and checked the
Seamless Tones and Colors option, which helps prevent 'ghosting' when different parts of each layer are displayed together:
XXL then performs its magic, creating a mask for each layer which only allows the in-focus part of each image through:
The final image has each Thunderbird perfectly in focus. How neat is that!
