Following our 'Training Evening' on 5th Feb 2015, Stephen Goodfellow circulated some useful information about focus-stacking which desreves to be perserved for future reference - thanks Stephen!
Focus stacking is the combining of several images to create one photo with a greater depth of field. It is mainly used in macro photography where you have to deal with small depth of fields.
First you'll have to shot several photos using a tripod. In each image you'll put the focus point a bit further away on your subject. Make sure you've got some overlap in each image.
If you have Photoshop CS4 or a newer version you can stack your photos in Photoshop. Start by loading the photos into Photoshop and putting them together in one file. Each photo should have its own layer. The order you use is important; each new layer should be the next step in focus depth. If you mix them up stacking them won't work.
When you've got all the photos together in one file, select all layers. You can do this by clicking the top layer in the layer palette, hold down your shift key and click the bottom layer. All layers are marked blue now. Go into the edit menu and choose auto-align layers. In the window that opens, just select ok. The automatic mode should do the trick. This process aligns the layers so any movement in between the different shots is corrected.
Next step is combining the layers into one. Again, choose the edit menu, but this time select auto-blend layers. In the window that appears you choose the blend method Stack Images and also check the Seamless Tones and Colors. Press ok do let Photoshop work its magic.
In most cases the automated result will be good. If you find something to be off, you can correct it by editing the layer mask Photoshop created. You'll need to crop the edges out to get your final photo.
Here are five low-res images you can try it with:
and you should get something like this:
Because they are lo-res images the final result will look blocky when viewed at a high magnification, but the improved depth effect can still be seen if you compare the outcome with each individual image.
Since there are only 5 images to stack you may not achieve seamless depth of focus, as you might with 130 using specialised software, but you'll get the general idea and if you want to move on, the sky's your wallet.