These pages present a series of videos about scale model photography. Each of the important elements that contribute to recording the best possible image are discussed as they relate to photographing scale models.
It can be difficult to categorize cameras today as manufacturers continually mix form and features to broaden appeal to wider markets, but roughly speaking digital cameras fall into some basic types: Small compact cameras; cameras that can resemble a dslr but the lens isn’t interchangeable ... these cameras are sometime referred to as bridge cameras; Actual DSLR’s ... which are the digital equivalent of 35mm SLR; Mirrorless Interchangeable Lens cameras; and a variety of Medium Format cameras.
While you can use any of these to record an image, some of these have features that will allow you to achieve a better result. At the top of my list is the ability to use interchangeable lenses, so for me, I can quickly eliminate the compact and bridge cameras from my list of possible best choices. Likewise, medium format digital cameras are simply not practical for a number of reasons. This reduces my field of choices to either a DSLR or a Mirrorless with interchangeable lenses.
So what’s the difference between a DSLR and a Mirrorless? With a DSLR you traditionally frame and focus your image through an optical viewfinder. Light comes through the lens, is reflected off a beam splitter mirror, bounces around a mirrored prism and then finds its way into the eyepiece. If you use the autofocus function, the camera uses an autofocus sensor that gets the image from the light passing though the beam splitter. In both these cases, when you actually take the picture, the mirror flips up and the shutter is tripped. If the DSLR is capable of live view shooting, the mirror flips up and you use the actual image sensor and LCD screen on the back to frame and focus.
In a mirrorless camera, the light passes directly onto the image sensor which is used for direct framing and focusing. If the camera is equipped with an eye-level viewfinder, the image in the finder is actually a small digital display.
Precise focusing is key when photographing scale models. Because depth of field is so shallow with our small subjects, there isn’t a much room for error. Trying to rely on autofocus can be hit or miss, so in the end, my choice of camera is going to be a DSLR that can shoot in live view or a mirrorless camera.
The next must-have is a good image sensor. Here’s where you face the fact that all pixels are not created equal. Sensors come in a variety of sizes and architectures. Most all the current high-end cameras use an image sensor that’s known as a full frame sensor. A more common sensor size is the APS-C ... This type of sensor is also termed a crop sensor ... The reduction in size is expressed as a Crop Factor ... Typically this is 1.5 .. but Canon uses 1.6 ... So for instance .. a camera with a 1.5 crop sensor has a sensor with .666 the area of a full frame sensor...
The reduced area of the crop sensor means that the pixels are smaller and the images typically exhibit more high ISO noise than from a full frame sensor ... but I find this is pretty much a non-issue for my use because I rarely ever shoot above ISO of 200 .. and my finished images are relatively small ... One advantage to us as modelers ... is that smaller sensors offer a greater depth of field ... However .. there’s a limit to how small the sensor can be and still produce an acceptable image ... which is why images taken with phones and ultra compact cameras don’t hold up well when viewed on anything larger than an eight inch display ... The architecture and structure of sensor design has many permutations but sensor performance is a key element when choosing a digital camera.
The sensor isn’t the only new bit of the digital world. The firmware that runs the camera is equally important for maximum performance and functionality and I’ll be talking about the specifics throughout this series, but I would encourage you to download the manual for any camera that you are considering so that you can survey the menu system and review the functions and customizations are available.
Since the cameras that I’ve suggested have interchangeable lenses, what lenses might be a good choice? The first is what I think of as a general purpose all-round zoom that ranges from around the 20’s to the 105 - 135 mm range. This lens is the workhorse when you’re imaging your entire model.
My second must-have lens is a macro lens with a focal length of 100 or 105 mm. Macro lenses focus in much closer ... most often at a 1 to 1 magnification. That means that the image on the sensor is the actual size of what you focus on. I prefer to avoid short macro lenses like a 50mm because the working distance is so close that it limits many lighting options. Macro lenses are your best choice for those close up detail and construction shots.
If your budget doesn’t allow for a macro lens right off, there are a couple of alternatives. The first are magnification filters that screw on to the front of your zoom. Second are extension tubes that move the lens further out from the body. The tubes are a better choice because they eliminate any further optical issues that might come along with the filters. However, neither of these alternatives offer the other big advantage of a macro lens ... which is that macro lenses typically offer much smaller f-stops .. like f-32. Smaller f-stops are a key factor in improving depth of field. Also, generally speaking, macro lenses are better optically than standard lenses.
One of the challenges with photographing scale models is keeping the entire model in focus. Small objects like our models, require that the camera be close to the subject relative to the focal length of the lens and sometimes this can prove challenging as it exceeds the optical capabilities of the lens and camera to render a satisfactory depth of field.
Depth of field is defined as the “range of distance that appears acceptably sharp.” There’s nothing precise about “range” ... “appears” ... or “acceptably.” The reason depth of field can be confusing is that we’re talking about perception.
Some of the variables that can affect the DOF are: Focus Distance; Aperture of the lens; Diffraction; Depth of Focus; Sensor Size; Post Processing; Print Size.
How these factors relate to each other can also be affected by the hardware. Not all cameras, lenses and displays are the same, so while I’ll be talking about the individual factors that effect DOF, the information is basically a guideline. Ultimately you have to do some playing around to maximize the results with the equipment have available.
Depth of field doesn’t change abruptly from unsharp to sharp, the transition is gradual. In fact, everything in front or back of the actual focusing distance begins to lose sharpness, although it may not be perceived by our eyes. The term CoC is used to describe how much a point needs to be blurred in order to be perceived as unsharp. When the CoC becomes perceptible to our eyes, the area is said to be outside the depth of field. One rule of thumb is that a circle is considered acceptably sharp when it would go unnoticed in a standard 8x10 print viewed from 1 foot. Camera manufacturers assume a CoC to be negligible if it isn’t larger than 10 thousandths of an inch. This is the standard that they use for the depth of field markers you see on lens.
The two most common variables you can use to control depth of field are Focus Distance and the Aperture of the Lens. Simply watching the lens depth of field markers will demonstrate how depth of field increases as the focus distance increase. So rather than filling the view finder with the subject, you can easily increase the DOF if you back off from the model or zoom out a bit if you’re using a zoom lens. However, you don’t want to move back so far that you finally end up with a low resolution image.
This effect has nothing to do with the focal length of the lens. If the size of the subject is kept constant, the DOF stays basically the same with any focal length lens. What does change is the distribution of the DOF.
The second common variable is the aperture of the lens. The smaller the aperture, the greater the depth of field. There are two considerations when using small f-stops ... Diffraction and Depth of Focus. Diffraction is an optical effect that occurs when light is bent as it passes through a hole. All lenses exhibit some amount of diffraction and it increases with smaller f-stops like f-22 or f-32. Not all lenses handle diffraction the same and every lens has its sweet-spot which is generally two stops down from its maximum aperture.
The second consideration is depth of focus. A rudimentary way to think about depth of focus is to think of it as depth of field, but between the lens and the sensor. The angle of the light and how well it’s focused on the sensor plane creates its own sort of a circle of confusion. How this relates to the individual pixels on the sensor can have an effect on image sharpness. Large apertures create wider angles that have a narrower depth of focus, while smaller apertures result in a narrower beam that has a greater depth of focus.
Another way to effect how light is focused on the sensor is by manipulating the lens plane. The most common example is a large format view camera, however the same mechanics can be adapted for a small format camera as well with the use of a bellows and rails. or to a lesser degree within a single lens known as a tilt shift lens.
Even though we do our best to maximize DOF optically ... how the image is manipulated in processing can mitigate many of our limitations. For instance, just reducing the original image size has the effect of sharpening the entire image. An image that looks soft at a width of 5500 pixels will appear sharper when reduced to 1200 pixels ... and if the image is destined for the web, it may look just fine.
Another method for improving depth of field is to use a series of images merged together in a process called focus stacking. I cover this technique at the end of the video on depth of field.