First, it is very important to define exactly your project. The best way to do so is a sketch. A rough one can be enough, you don't need to be a very skilled drawer. Here is one of my "best one":
As you can see, it is not extremely good, but it is enough to see exactly where all the different items are located. Once you are happy with the overall composition, start counting the various photos you are going to need. In this example, one can see that at least those ones are needed:
- Model in main position
- Model's left arm in 2 other positions
- Model's right ram in 1 other position
- Model's hair (either in 1 shot if you manage to do so, or in several photos to created the needed shape)
- Other model hands (x6)
- Burning paper for fingers
- Some ashes
If everything goes well then you should be able to reach your goal decently:
Of course, to get there, there are a few parameters to take into consideration to shoot your photos appropriately.
2) Light direction
You really need to define, very clearly, where is located your main light source. This must be done at the "sketch" time: you absolutely need the information before taking any photo.
You can have several other "minor" sources, depending on the scene, but a main one is highly recommended (as it usually gives prettier results). Once you decided that, ALL your photos must comply with the decision. There is no need (at all) in spending time masking many layers carefully, softening edges, adding sand, or covering them with whatever special effect if the lighting is not consistent: it just won't look right, whatever you do. For example if you decide that the main light comes from the lower left corner, all your photos must be lit the same way.
For all the photos taken in a controlled environment, such as your home studio (or your kitchen, or whatever), it is relatively easy: move your lighting gear and/or your model appropriately. Here is an example: photographing a baby can be challenging, but if all the lights are positioned and you already know where everything will be in advance, it could be a matter of seconds.
The lighting on the face was good enough, so very few editing was necessary about it in the final composite:
Of course the temperature of the lights were adjusted (but even that could have been done at shooting time, with colored gels on the flashes).
If you need outdoor photos, it can be quite complicated, because you usually become dependent on weather and sun position (especially for landscapes or architecture). In order to help you find the good location for your photos and the good time, it is probably better to use an application such as SunCalcor TPE.This way, you can foresee where the light is going to come from, and define the best time to travel to your shooting location.
3) Light intensity
There is a very simple rule: the closer to the source, the brighter and contrasted the subject. You need to make sure to "sort" brightness and contrast levels accordingly to the main light source location. This means you could have to take "bad" photos (i.e. underexposed/overexposed). Remember, you are not taking photos that are going to be used separately, they need to work as a whole in the final composite. Technically, this can be a bit tricky, since modern cameras will automatically try to obtain optimized exposure: if you want to go against it, you need to set your camera in full manual mode, and adjust the settings by yourself. Of course, this goes way beyond the purpose of this post, but try to learn how to use your camera in each mode, and do not be afraid to experiment with it.
Just like for the light, direction and intensity are the keys. However, for shadows, the intensity rule in inverted: the closer to the source, the darker. And of course, shadows far away from the source should be less intense (i.e. less dark). Since creating shadows can be sometimes difficult in post-processing (especially when the environment has complex shapes), you can try photographing shadows for more realism. In order to do that, you need to create the real shadow on a white ground (which is easier at home, for example using a large white sheet). Then, simply use you photo in a "multiply" mode layer, and you should be able to position your real shadow in the composite.
5) Depth of field
It is important to also keep in mind the location of the focus plane, and photograph the different elements accordingly. Just like with the light position, you need to define your focus plane location, i.e. where the photo is "sharp" and where it is "blurry". In the example below, while the baby is in focus, the fishes in the foreground and in the background are blurry:
While it is of course possible to blur things in post processing, sometimes blurring them in-camera gives much nicer results: against, experiment all you can to get the best results!
If you want your composite to be sharp from front to back, then you need every single photo you take to be sharp. To get there, you are going to need small aperture on your camera, such as f/18 or f/22. This can imply using a tripod and a remote. If this is not enough, you can even use focus stacking methods (but you will need a tripod too, of course). Here is an example where I had to use focus stacking, since a standard macro photo of a fly would have resulted in a very narrow depth of field:
6) Atmospheric depth
This can be useful if you want to compose a picture with items positioned very far away in the background. Air is not transparent, even when there is no rain, fog, clouds, nor anything. Air make things less contrasted, a bit like if a white filter was between you and the item. This is often obvious on landscape shots: mountains in the background are much less contrasted than things in the foreground. If you can, try adjusting your lighting to obtain such result for items that will end up far away in the background.
Here, the persons in the background were shot with that in mind:
8) General hints
As you realized, there are several things you must know before grabbing your camera:
- Main light location. This is super important, and you must take all your photos with the main light in the same relative position. With animals, children, or anything moving fast and hardly controllable, it can be a nightmare. Good luck For convenience, I shot everything I can (small objects, models, etc.) in my home studio, so that I can precisely adjust lights intensity and positions.
- Composition. If you don't know where your items will be positioned in the final image, chances are you won't be consistent focus-wise or light-wise. I usually sketch my composition beforehand (very roughly), so that I have all that information. If unsure, take photos with everything sharp: while you always can add some blur effect afterwards, if you need things sharper (as for your entry's foreground), you're stuck.
Also, take your time when reviewing your photos and selecting them for the composite. Do ask yourself the questions we mentioned:
- Are my items lit from the right direction?
- Are my items lit with the appropriate intensity? (the closer to the main light source, the brighter)
- Are my shadows going towards the appropriate direction (opposite of the main light source location)
- Are my shadows intensities appropriate? (the closer to the main light source, the darker)
- Is my depth of field consistent? (no sharp items where the main photo is blurry, no blurry items where the main photo is sharp)
- Is my color balance consistent? (no items lit in blue when the main light is yellow, etc.)
- Are my items in the far background less contrasty than the ones in the foreground? (especially in landscapes)
Hope this helps!